aiming Dr. Dave's answers to frequently-asked questions
(FAQs),
mostly from the BD
CCB and AZB
discussion forums
maintained for the book: The
Illustrated Principles of Pool and Billiards,
the DVD series: The Video Encyclopedia of Pool Shots,
and the monthly Billiards
Digest "Illustrated Principles" instructional articles
for
more information, see Section 3.02 in The
Illustrated Principles of Pool and Billiards
and Disc I of the Video Encyclopedia of Pool Shots
How do different people aim?
My October '08 article has some good illustrations and explanations related to aiming. See also: DAM aiming system.
I don't use the common fractional-ball aiming systems presented in TP A.11. I just presented them to show that they are the same geometrically.
I personally use a combination of straight intuition (just "seeing the angle"), ghost ball aiming (see NV 3.1, NV 3.2), and contact point visualization (see NV B.3). Bottom line: I just visualize the aim without using any kind of fractional-ball or fixed-reference compensation system. I certainly don't use any kind of math or numbers when I aim, like some people have suggested.
I think (but don't know) that if a scientific survey were done with all of the pro players, many (maybe even most) of them would say that aiming comes naturally (i.e., its "intuitive" or they just "see the angle"), because they have played so much. Some people might find the How the Pros Aim article interesting; although, it is not the result of a rigorous scientific study.
from Spiderman:
You are correct, that is a fine article. But, as even that author concludes, it will never be "put to rest". Luckily, it doesn't really matter. The numerous pros interviewed used a vast and disparate array of aiming techniques. "Ghost Ball" seemed to be the only somewhat-recurring assertion, but not to a dominant extent. There were even one or two who claimed to aim by "feel".
Personally I use the "ghost ball" technique most often, but not to exclusion of others. I learned to play with no coaching, and "ghost ball" was something I thought I invented . I didn't learn what everyone else called it until I read "99 Critical Shots". Now on some simple shots I just let the subconscious handle aiming - all I visualize is the desired result, and it happens, right down to how much the CB path distorts from the draw, and how far it rolls after the second rail. On very thin cuts I may visualize actual ball-to-ball contact points. But on ALL caroms I fall back to an augmented ghost-ball alignment. Most players will hit caroms too thick if they rely on feel.
What I would like to stress from that article is the one thing that everyone interviewed DID have in common - "the balls went in" for them.
The fact that so many different methods will work, and work well, ensures that some will die convinced that "their" way is "the only" way. Clearly all brains are not wired alike, and no one technique is ever going to be a panacea. Use what works for you, as long as it makes sense.
from Bob_Jewett:
You may find one of the following articles useful. I included the article about finding the center of the pocket because if you don't know where that is, it's pretty hard to aim well.
http://www.sfbilliards.com/articles/1993-06.pdf -- close ball aiming
http://www.sfbilliards.com/articles/1996-02.pdf -- frozen ball aiming
http://www.sfbilliards.com/articles/1997-04.pdf -- finding the center of the pocket
http://www.sfbilliards.com/articles/1999-11.pdf -- a smorgasbord of systems
http://www.sfbilliards.com/articles/2000-06.pdf -- analysis of three systems
http://www.sfbilliards.com/articles/2004-06.pdf -- ferrule system, lights system, overlap system
http://www.sfbilliards.com/articles/2004-12.pdf -- aiming devices
http://www.sfbilliards.com/articles/2005-01.pdf -- some more devices
http://www.sfbilliards.com/articles/2005-06.pdf -- a history of parallel aiming [/quote]
Why are some basic cut shot "aiming systems" helpful and effective?
Any "system" that forces a person to focus on aim and alignment consistently and with concentration will be beneficial to many people, especially people who currently don't focus well or long enough.
from Colin Colenso (concerning 90/90 and CTE pivot-based systems):
I wanted to make a post listing what I perceive to be the strongest advantages of these systems.
I think these advantages are the main reason players often find great success aiming and shooting this way.PLAUSIBLE CONTRIBUTING FACTORS:
1. Sighting point to point helps one to perceive an exact line and to take in the positions of the two balls relative to this line. In other words, they use a repeatable fixed method to visualize the ball positions.
2. These systems put you either right on line to begin with or in the ball park when used for appropriate shots.
3. In the pivot phase they move from this fixed line to another visual line that they perceive through the center of the CB. This finding of an aim line forces the mind to be decisive and exact. I believe forcing this decisiveness trains the mind not to wander and to make better decisions than just feeling around back and forth hoping to feel a ghost ball or contact point angle.
4. I suspect this one is the most powerful factor in these aiming methods. They force a player to commit to a pot line and then strike the cue dead straight through that line, rather than to swoop sideways on the shot as almost all beginners do. Because they focus hard on their pre-stroke alignment, they trust this line and stroke straight. If they do miss certain shots they will soon compensate with their aim until they learn to see the correct line. The normal player very often aims thick on their cut angles and swoops a little to make the cuts. When they try to bring speed or english into those shots they meet with many difficulties. So using any system that forces a player to adopt strict and accurate pre-alignment, followed by a straight stroke, should meet with considerable success and consistency after intensive practice.
5. Because players learn to trust their pre-alignment they begin to be able to relax during the actual stroke. This takes tension out of their arms and body and they can begin to execute with better speed and a more satisfactory feeling during execution. This may explain the feeling that they feel like they just pivot, bang and the ball goes in.6. A system that requires a focus on the positioning of the cue may cause the player to be more highly aware of the line of cue. In standard aiming, some players may glance a little at the tip and CB but be mainly focused at the OB and therefore not getting much visual feedback from their cue, which is a straight line guide waiting to be used. Also, this cue position awareness may lead to a more constant positioning of the eyes over the cue. This is quite different to the normal play experience where there is a tendency to ride the ball into the hole. This occurs when players don't trust their alignment and tend to swoop a little to ride the cue ball to the correct point. This method of playing tends to make one have to work physically and mentally during the stroke. When pre-aligned well, the stroke is simply a matter of swinging the cue.
7. Using these systems may represent the most organized approach they have attempted for aiming. Several aspects have been compartmentalized so that each of these aspects can be focused on more clearly and developed individually. This organization may also assist in allowing the player to relax through the early implementation stage and then put their entire focus into the final alignment stage.
8. While sliding or shifting the cue into the final line of the shot, players may be incorporating a method that helps them to sight the required line of aim. This may be due to coming across the line, from left to right or vice versa, such that the sighter gets a feel for how the line of aim is moving relative to the position of the OB.
The only thing I don't agree with regarding these systems is that the systems find the aim line. I think it is the players that align themselves (via slight intuitive adjustments) to the correct aim line when need be. It will take them a little while to develop this ability for a wide range of shots.
from JoeyA:
When using virtually any aiming system, most people are really "paying close attention" to what they are doing. When you pay close attention to what you are doing you focus better. I watch the pros playing in the big tournaments, guys like Archer, Stevie Moore, Charley Bryant, and dozens of others who pay "extra attention" on particular shots and the extra attention apparently pays BIG DIVIDENDS.
imo, the best things about Aiming systems is that they help your eyes and mind to pay closer attention to what you are attempting to do.
from Mike Page:
If something seems to work or to help some people it IS important to many of us to understand WHY it helps. Part of this--most of us are here for fun when it comes down to it--is intellectual curiosity, but a big part of it is understanding what specific problems are solved by a particular approach to be able to incorporate and communicate those things directly and extend them to new situations.
There are reasons why beginning every shot the same way--looking full on or looking at the half-ball hit for instance--might be useful. The "SEEing it (from manual repetition)" you described above benefits from approaching the same shots the same way every time.
There are other reasons some of these approaches--whether it's one of Hal's methods or S.A.M. or whatever is being discussed here--help people. Get ready, because there's a big secret coming... These approaches cause people to do something they don't usually do. It's such an important thing that we have a name for it. It's called AIM. That's right.
If you look at the QUIET EYE studies, you will find one bit of consistency about the studies of pool, of putting, of basketball free throws, and of other aims involving stationary targets. Consistently a group of experts is compared to a group of wannabes. Consistently the group of experts GAZE at they target on average for a notably longer period of time in the "set" position. I'm talking maybe 2.5 seconds versus 1.5 seconds. It has become increasingly clear that this slightly longer gaze time--locking on your target for enough time-- is crucial for processing the information necessary to aim successfully.
Let's suppose many people suffer from inadequate GAZE time. IF true, then showing them a new method that forces them to lock in on the target (while following whatever the prescription is) will increase their success rate. Like the poop-on-the-swingset, the method might just be a mechanism to bring out the real solution (water/quiet-eye gaze time).
I point out in one of my aiming videos that I think another reason for any success people find with fractional ball aiming techniques is it causes them to sight parallel to the line the stick is moving. Many people don't. Many people sight from above the stick to the object ball contact point. This line is not parallel to the line of the stick or the cueball motion.
Please understand that when someone suggests a method that SEEMS to not have the gaps filled in, that SEEMS to have shots that require two different angles to receive the same aim, that SEEMS to request the exact same aim for two sticks that we know squirt differently, it is like a giant bell going off for many of us.
Then if rather than taking off the system's clothes so that we can examine it honestly, the proponent points out that you really have to learn it in person or that such and such a world-class player uses it, it's like another giant bell going off.
... focusing on center-to-edge or edge-to-wherever gets your site line parallel to your stick. This could be a key for you to unlock the aim you really already have.
Or perhaps focusing on a shot from the edge of the cueball and pivoting toward the center--like being discussed here--locks a person into an eye dominance that is different from what he would have done going straight down into the shot and gives him a perspective that works better for him.
My point is if these sorts of advice help certain people under certain circumstances pocket balls, then that's great. But it is very different from the aiming system "working." These people are actually finding their own aim; they're just approaching their own aim from a different angle.
from Patrick Johnson:
Here's what I think makes [aiming systems] work: they're systems for players who have "aiming instincts" (what we usually call "feel") that function very well, but they have to "trick" themselves into letting it happen fully. The system helps them "get out of the way" mentally so their aiming instinct can function effectively.
There may be a problem (too much thinking, too much doubt, whatever) or the system may simply be an improvement, but I think that by convincing the player that instinct is taken out of the picture (by seeming to work "mechanically" for every shot just by following the same simple instructions), the system allows the player to release his innate aiming ability to "freewheel" and make the shots it's capable of.
In a way it's like "getting into the zone" at will - and in this sense it's an ability I envy. That's an aspect of these systems I find very intriguing - I think they may teach us something about how to find "the zone" more easily and more frequently.
from JoeW:
I suspect that aiming systems give people a reference point from which to think about the shot. Some players may or may not be aware of the idea that for some shots their subconscious makes adjustments.
On the one side aiming systems provide a zone of comfort for the player because they work in some (many) situations. This in turn leads to confidence when shooting and the player, over time, learns to compensate as needed.
On the other side it can be demonstrated that some aspects of these systems can not work as described. Proponents of the system seem to indicate that these systems take several weeks (?) to learn. However, the concepts are basically straightforward and could be briefly described and learned in a few hours. Weeks of training are required because the systems involve the development of "feel" though the user may not be aware of this aspect and therefore does not have to trust their natural sighting ability which is being developed within the system. For the present they have a system that can be relied upon.
In a sense, a player could be taught any of several systems and they all would work equally well if the player is willing to trust the system.
The conclusion is that one may seek the limits of the aiming system to learn what is useful for some particular shots from a physical basis and this may contribute to the development of a new, more advanced, system.
However, finding the faults with a system that does work for some people is antithetical to the progress we all seek. There is no need to preach to either choir. No one has ever been converted in this way. What needs to be sought is an exact description of the system by the primary theorist and then studies on the theoretical limits of the system. The results could be a new system that might have some appeal.
No matter what system is developed, I suspect that we all know it too will have limits. Pointing out limits to those who are proponents of the system is inherently antagonistic. They already know their system and have consciously (or not) made adaptations at the system's limits.
My point is that little is to be gained by pointing out the limits of a system to those who are proponents. The discussion is better held among those who are interested in such things. When proponents take offense, as Ron V seems to have been offended, the answer provided by Dave is sufficient to explain that no one particular system is or was under attack. And of course it is necessary to tread lightly among those who believe in any of several systems. Strongly held beliefs have started more than one war.
Why is aiming so difficult for some people?
Aiming is tough because it involves 3D visualization, visual perception, physical and visual alignment, and compensation for CIT (with no English) and/or squirt/swerve/throw with English.
from Patrick Johnson:
Aiming isn't a science, despite what some system [people] think. It involves many kinds of estimation:
- estimating where the OB contact point is by aligning it with the pocket, from a distance and an angle
- estimating how to adjust the OB contact point for throw
- estimating where the CB contact point is by imagining where it is on the "dark side" of the CB (this is part 1 of the subject of aiming systems)
- estimating how to align the CB and OB so the two contact points come together (this is part 2 of the subject of aiming systems)
- estimating how to position your head and eyes so all the above things are visualized correctly (this is part 2A of the subject of aiming systems)
This is only a partial list of the estimations required just for aiming (not stroking), and only for shots without sidespin (don't get me started).
Even with a perfect stroke aiming isn't a simple, mechanically repeatable process.
from Colin Colenso:
I think that the biggest error that most players make when trying to become more accurate players is when they presume that their missed shots are caused by poor Stroke Mechanics, while they overlook the most common and significant cause which is poor Initial Alignment.
By Initial Alignment, I basically mean the positioning of the bridge point.
If you do not get your bridge to a point + or - a millimeter or less from the required line, then you are going to have to play an off center or sweeping stroke to pocket the OB as hoped.
In fact, it is common for players to subconsciously make this stroke adjustment when they feel that the shot is not going on line. This creates tension in their swing...their brain is fighting their heart is one way to describe it. So after they miss, they recall the sense of tension in the stroke, so confusedly start practicing their stroke, blaming their wrist action or some other aspect of stroke mechanics which is usually just a symptom of their poor Initial Alignment.
So to establish some proof for my contention, I set up a test.
A mechanical bridge was wedged into position. A piece of chalk sat under the rail as a firm point to keep the bridge from moving. CB and OB were put into positions that lined up for pocketing to the corner. Once established, I tapped the balls into place marked by a cross on the cloth. Hence I could replace the balls to almost identical positions each shot.
Using the bridge, fixed in place, my stroking did not feel very stable, yet I was able to pocket this shot 20 times in a row with very little variation in the pocketing accuracy. Not a single time did the OB hit the jaw.
Now I could make this shot miss by striking deliberately with english, but the point is, that it's not hard to hit the CB center ball accurately enough to provide satisfactory accuracy for most shots on the table.
The hard part is getting the bridge hand in perfect position for the shot...that is, to align perfectly.
from Patrick Johnson:
You'll always aim by feel; no system will change that. Even with the "systems" that show you exactly where to hit the OB ("ghost ball", "double overlap", "paralleling") you need to "feel" when you're lined up exactly right and "feel" how much adjustment to make for OB throw and CB squirt/swerve.
And most systems don't show you exactly where to hit the OB; they give you an approximate aim point (which you have to line up correctly by feel) and from that you have to adjust to the real aim point by feel. "Approximating" systems include all the systems that are not the well-known "exact" systems I named above.
"Approximating" systems include those taught by Hal Houle, Cue-Tech, RonV, Stan Shuffet, Joe Tucker and others, going by such names as "fractional aiming", "3-angles", "S.A.M.", "center-to-edge", "Pro 1", etc., etc. Some users and teachers of these systems will tell you that they are "exact" systems that need no adjustments, but they're wrong. All of them are approximation systems and all of them require you to adjust your aim by feel. The only one that I'm aware of that actually admits this fact openly is Joe Tucker's system.
Confidence is essential to increasing your "feel" for aiming, with or without an aiming system, and one of the main benefits of using a system is that it can help boost your confidence by narrowing down the range of choices you have to make by feel. Even players who don't think they use any system often use one (or more) unconsciously - for instance, when faced with a tough shot they might get a "second opinion" on their aim by imagining how "ghost ball" or "double overlap" aim would look. Many players use different systems for different kinds of shots - for instance, the "double overlap" system is especially useful for long thin cut shots.
Whether or not you use a system(s) and which one(s) you use are personal choices. Hopefully understanding exactly what aiming systems are and are not before you make those decisions will help you make the right ones for you.
aim compensation for squirt, swerve, and throw
Is there a style of play (e.g., using aim-and-pivot aiming methods) that can compensate for all of the effects of squirt, swerve, and throw?
Background information on important related topics can be found here:
There is no sliver-bullet "style of play" that can magically solve all of the "challenges" associate with compensating one's aim for squirt, throw, and swerve. The BHE and FHE aim-and-pivot methods (see my November '07 article) can be used to adjust for squirt (and in some cases the combination of squirt, swerve and/or throw, using an "effective pivot length" for each shot), but swerve and throw vary too much with shot speed, shot distance, cue elevation, type and amount of English, amount of forward roll, ball and cloth conditions, etc. I think the best you can do is be knowledgeable of all of the effects (e.g., see my March '08 article summarizing squirt and swerve effects and my June '07 article summarizing throw effects) and/or have solid intuition based on many years of successful practice and play. There is no magical "style of play" that can solve all of the world's problems. Pool is hard.
See also:
The BHE method can be used to adjust for both squirt and swerve if you adjust your bridge length based on the distance and speed of the shot. Basically, at slower speeds and greater distances between the CB and the OB, a longer bridge length is required because the "effective squirt" (or squerve) is reduced due to swerve. This will only work with a near level cue, because with an elevated cue, swerve becomes a larger factor and can make "effective squirt" negative. Also, with a follow shot, swerve happens sooner than with a draw shot (of the same cue elevation), giving less effective squirt (squerve), so again a longer pivot length would be necessary. Colin Colenso has come up with some experiments and formulas to help methodically determine the required effective pivot length (i.e., required bridge length) for any shot (see below).
from Colin Colenso:
It's little wonder that pros are adept at, and usually rely almost solely upon simply estimating how to align to any shot they want to make using english.
There really has been no other way to learn how to execute english for a wide range of shots. So they learn a huge range of shots by repetition and this gives them the intuitive feel to make, or get close to almost any shot they attempt with varying degrees of cut angle, speed and tip offset.
When I first learned about BHE a few years ago I thought it was some instant quick fix. But I soon learned that there were variables that affected the success on many shots quite significantly. These are:
1. The effective pivot point changes according to speed and distance traveled. (Swerve is the culprit).
2. The actual contact point required to make shots varies considerably with CB speed, cut angle and type and rate of spin on the CB.
So without knowing how much to adjust for all of these variables, BHE is only useful for a limited range of shots.
[Here is a method, with formulas, that can be used to select a bridge length to compensate for both squirt and swerve, assuming you have already adjusted your aim for any throw effects.]
PPe = PPi + DVK
PPe = required effective pivot point for any shot based on distance and shot speed.
D = Distance from CB to OB (or target) in feet.
V = Velocity Factor where 0 is maximum speed and 4 is slow, or one table length roll including bouncing off one rail (see below).
K = correction factor to account for cloth slickness given by:K = (PPe* - PPi) / 15
PPi = The Intrinsic Pivot Point. Estimated by finding the effective pivot point for a shot over 5 feet hitting at maximum velocity, such that swerve has insignificant influence on the shot. My cue's PPi is 9.5 inches. Low squirt cues are 12 to 14 inches.PPe* = the pivot point required for a 5 foot shot at speed factor 3, which is medium slow, enough to bounce 2 rails back to the original position. This figure will be different for each cue on each table. It brings the slickness variable into the formula.
My preferred cue on my table has PPe* = 13.7 inches. (This could change with humidity changes). It's PPi is 9.5 inches, so my K value for my cue on my table at the moment is (13.7 - 9.5)/15 = approx 0.28. 0.28 is the adjustment needed at distance 1 foot and speed factor 1. The number 15 is derived from the PPe* being at 5 foot at speed factor 3. 5x3 = 15. PPe* could use any shot as a basis with a different numerator, but 5 foot is a good number because it is about the length of the cue, it can be played with little elevation and it is long and slow enough to provide a decent difference with PPi, hence giving it a reasonable margin of error. PPe* can vary by around 2 inches depending on cloth slickness. It is a number that can be derived pretty accurately within half a dozen hits on a new table.
So for any shot my PPe = 9.5 + D x V x 0.28
So if I have a shot at speed factor 2 over 4 feet my PPe = 9.5 + 2.24 = approx 11.7 inches.
Below is a chart with PPe's for the full range of speeds and distances for my cue. You should be able to plug data into this formula and get PPe's that correspond to those in the chart. Note: The key to making this formula simple was creating the methodology of the speed factor. In the chart below, the speeds are divided into 6 markings, rather than the 5 for speed factors 0-4.
General Speed Factor (V) Rules are:
0 = Max speed, would bounce about 5 rails.
1 = Firm speed, would bounce 4 rails and back to starting position.
2 = Medium speed, would bounce 3 rails and back to starting position.
3 = Slow-Medium speed, would bounce 2 rails and back to starting position.
4 = Slow speed, would bounce 1 rail and back to starting position at center table.
[To compensate for how squerve changes for draw vs. follow shots (for more info, see Dr. Dave's March '08 article), we can also make an adjustment to the pivot point based on the height of the cue:]
Based on the above observation I was able, via some testing to establish a pivot point adjustment key depending on the height the cue ball is struck with english.
Strangely enough it seems to work pretty well independent of distance, speed or cue offset. Though this hasn't been tested comprehensively.
So the total PPe Effective Pivot Point formula, as it has been refined is:PPe = PPi + DVK + H
H = Height of hit on CB using the numbers given below in the diagram.
(Note: In most practical cases we don't need to hit higher than the 1 range. Most draw shots fit into the -1 range.
For a low squirt cue, such as a Predator Z, I would increase the numbers in the below chart by about 33%. So they might range from 4 to -1.3. Current information suggests the Predator Z has a natural or intrinsic pivot point of between 12 and 13 inches, compared to a normal shaft which is in the 9 to 9.5 inch range.
What squirt, swerve, and throw effects do I need to be aware of?
As many of you probably know, I have done lots of analysis and experiments over the years concerning squirt, swerve, and throw. Many illustrations, explanations, and examples can be found in my 2006 through 2008 BD articles available online.
Below is a quick summary of some of the useful pieces of information presented in the articles. Hopefully, some might find this list useful to validate many things you know already and/or to check if there are some effects you don't know about.
FYI, here's a short glossary of some of the terms used:
BHE: back-hand English
CB: cue ball
CIT: cut-induced throw
FHE: front-hand English
gearing OE: the amount of outside English that results in no throw
IE: inside English
OB: object ball
OE: outside English
SIT: spin-induced throw
squerve: combination of squirt and swerve
See my online glossary and articles for more details.
Squirt, Swerve, and Throw
Effects:
(everything you ever wanted to know about squirt, swerve, and
throw)
1. Squirt increases with the amount of English.
2. Squirt does
not depend on shot speed (see my September
'07 article).
3. Squirt increases with the amount of shaft end-mass (e.g.,
a low-squirt cue has less end-mass and results in less squirt).
4. Squirt
is less with a heavier CB.
5. Squerve can be zero with certain speeds and
cue elevations for a given shot distance, amount of English, and cue.
6. Squirt
or squerve can be canceled using back-hand English (BHE) and/or front-hand English
(FHE) aim-and-pivot methods (see my November
'07 article).
7. Swerve increases with cue elevation and the amount of English.
8. Swerve occurs
with practically all English shots because the cue must be elevated to clear the
rails.
9. Swerve is delayed with faster shot speed.
10. Swerve occurs
only while the CB is sliding; once rolling begins, the CB heads in a straight
line.
11. Swerve occurs earlier with sticky cloth and later on slick cloth.
12. Swerve occurs earlier with a follow shot than with a draw shot (see my March
'08 article).
13. Swerve angle is larger with a draw shot than with a
follow shot (see my March
'08 article).
14. Swerve angle can be predicted and visualized using the
Coriolis masse-shot aiming method presented in my November
'05 article.
15. For small cut angle shots (i.e., fuller hits), the amount
of CIT does not vary with shot speed, but increases with cut angle (see my September
'06 article).
16. For larger cut angle shots (i.e., thinner hits), the
amount of CIT is significantly larger for slower speed shots as compared to faster
speed shots (see my September
'06 article).
17. The amount of CIT decreases some with larger cut angles,
but not by much (especially for slower speed shots) (see my September
'06 article).
18. Maximum CIT occurs at close to a half-ball hit (30-degree
cut angle) (see my September
'06 article).
19. In general, throw is larger at slower speeds, and for
stun shots.
20. Both follow and draw reduce throw, and they do so by the same
amount (see my October
'06 article).
21. The largest discrepancy between throw values for stun
and follow/draw shots occurs close to a half-ball hit (30-degree cut angle) (see
my October
'06 article).
22. The difference between the throw of stun and follow/draw
shots is not as great at larger cut angles (see my October
'06 article).
23. More English gives you more SIT only up to a point.
Additional English beyond that point actually reduces the amount of SIT (i.e.,
more English doesn't always give you more throw) (see my December
'06 article).
24. SIT is largest for a slow stun shot with about 50% of
maximum English (see my December
'06 article).
25. The amount of throw can increase significantly as a
small amount of English is added, especially for a stun shot (see my November
'06 article).
26. SIT is independent of speed (i.e., the throw is the
same at all speeds) for small amounts of English (see my December
'06 article).
27. "Gearing" OE results in absolutely no throw.
The amount of English required for "gearing" increases with cut angle.
At a half-ball hit, the amount of English required is about 50% (see my January
'07 article).
28. At very small cut angles, IE and OE create similar amounts
of throw (although, in opposite directions) (see my February
'07 article).
29. For large cut angles, a small amount of OE can result
in more throw than shots with no English (see my February
'07 article).
30. For large cut angles, IE results in less throw than
shots with no English (see my February
'07 article).
31. IE increases throw at small cut angles, but actually
reduces the amount of throw at larger cut angles (see my February
'07 article).
32. OE can cause throw in either direction depending on
the amount of English and the cut angle (see my January
'07 article).
33. Even for large cut angle shots (thin hits), excess OE
(more than the "gearing" amount) can be applied to throw the OB in the
SIT direction (see my January
'07 article).
34. The amount of throw with IE can be much more consistent
than with OE if the amount of English varies a little. In other words, the amount
of throw varies more with tip placement for OE vs. IE. This might explain why
some people prefer using IE on cut shots ... because they can better anticipate
and adjust for the amount of throw.
35. The least amount of throw, and the
most throw consistency, occurs with fast IE shots.
Does the size of the contact patch between the CB and OB vary with cut angle and speed, and does this affect how I should aim shots?
from Bob_Jewett:
The contact patch is larger according to how much energy is transferred from ball to ball, so a thin hit will have a smaller patch than a full hit, and a harder shot will have a larger contact patch than a softer shot.
One thing to remember in this, that a lot of people seem to be confused by, is that the size of the contact patch has absolutely nothing to do with the aiming accuracy required on a particular shot. The patch width does not give any indication of how precisely the cue ball must hit the object ball to get it into the pocket. In the same way, the contact patch of the tip on the ball gives no indication of how accurate you must be in tip placement to achieve a particular precision of placement of the cue ball.
bisect-pivot-and-shift aiming system
How does the "bisect-pivot-and-shift" aiming system work?
from bluepepper:
contact-point-to-contact-point or parallel-lines system
How does the "contact-point-to-contact-point" or "parallel-lines" aiming system work?
from jsp:
The first step is to draw a line going from the center of the intended pocket to the center of the object ball (purple dashed line). Extending this line to the opposite edge of the object ball gives you the object ball contact point (blue dot). To find the contact point of the cue ball, you simply just reflect ... as shown in the upper right portion of the figure.
Once you have the location of the cue ball CP, the next step is the draw a line through the object ball CP and the cue ball CP (green line). Then, you just simply imagine the line parallel to that line that goes through the center of the cue ball (orange line). This new line is what should direct your aim, since geometry tells you that this line connects the centers of both the cue ball and ghost ball. To make the shot, you just stroke through this line (black arrow).
How does the Center-to-Edge (CTE) aiming system work?
Here is the basic CTE aiming system, as demonstrated in the following video from eezbank:
For a “thick hit” (a small cut angle less than 15 degrees) to the left:
For a “half-ball hit” (close to 30 degrees) to the left:
For a “thin cut” (more than 45 degrees) to the left:
If you follow the procedures above exactly, you will make shots within certain limited ranges of angles. However, you will miss most shots outside of these limited ranges, unless the OB is very close to the pocket (so it can be cheated slightly) and/or the pockets are huge (so the margin for error is larger than normal). Now, you can make the procedures work if you compensate a little as the cut angle changes. For example, you can adjust your bridge length (this has a huge effect on the results of the pivot step per Diagram 4 in my December ‘08 article), change your head position to get a different “look” at the edge and center, modify the starting tip position a little, pivot slightly less or slightly more relative to the CB center, and/or you can shift your bridge hand slightly during the pivot (e.g., by pivoting with your hips or body) to create a different effective pivot point farther back or closer up from the bridge. You can also “air pivot” where you make subtle changes to all of this stuff intuitively as you come down into the shot (in which case you place your bridge and cue along the required line of aim of the shot with center-ball alignment, without using the separate tip-offset-and-pivot steps). Then, the system can work perfectly for any shot at the table, provided you can judge, perceive, and apply the subtle differences from one shot to another (in which case you probably don’t need an aiming system).
There are various versions of CTE floating around, but it is difficult to get useful information on how they work (e.g., see unanswered questions about CTE). Here are some example answers to some of the questions.
Here is a demonstration of how some forms of pivoting are used in conjunction with CTE and other pivot-based aiming methods: CTE pivot demonstration. If you vary your pivot from one shot to another (e.g., by shifting or deforming your bridge hand slightly during the pivot), you can bring the cue into the final required line of the aim for any shot. The cue can be moved laterally by the bridge hand during the "pivot" to create the longer effective "pivot length." And the amount of the lateral shift must increase for longer shots (and decrease for shorter shots). For really short shots, you need to shorten your bridge length to create a shorter pivot length. With the right initial alignment and the right type and amount of "pivot," CTE can be effective for every shot at the table. The "magic" is in the "pivot."
Many "challenges" relating to "aiming systems" are described and illlustrated in my November '08 and December '08 BD articles. These difficulties certainly apply to CTE.
from Colin Colenso:
1. Stare down the CTE line with the cue tip to the left.
2. Slide your bridge and tip into position picturing the line of aim relative to the CTE line.
3. Bring the tip up to center CB on this line of aim. The CTE line is in your peripheral vision.
4. Shoot straight. -use natural follow for consistent CIT. (A soft stun can cause you to miss the shot).
from 3kushn:
Line up for CTE. If the cut angle is to the left, place your tip on the right side of the CB then pivot to center (not moving the bridge) and stroke the shot. Just the opposite for a shot angled to the right.
from av84fun:
1. See the CTE line extended from the outside edge of the OB to the top center of the CB and thence toward the shooter.
2. Place your back foot on the extended CTE line and fall on the shot with your chin/nose descending down on top of that line.*
3. Land on the table with your bridge hand short of your normal bridge length with a certain spot on your bridge hand** directly on top of the CTE line.
4. Push your bridge hand up to your normal bridge distance on the "track" provided by the CTE line while pointing your tip to the outside edge of the CB at the equator.***
5. When you reach your normal bridge length, pivot the tip along the equator to the exact center of the CB. That is your Line of Aim. Note the spot on the OB that the tip points to. You will see that as the cut angle changes, executing the above procedure will cause the tip to point to different places on the OB and/or off the OB entirely on thinner cut angles.
NOTE that this method goes "off" when the CB and OB are very close together and when certain cut angles are reached. I find that the cut angle goes off at about that angle created by placing the CB at table center on the head string and the OB about 1/2 diamond below the foot string.
* It is actually correct have your nose/chin SLIGHTLY inside the CTE line.
** That spot is normally the inverted ^ formed by the index finger of the closed bridge or the center of the thumb pad of the open bridge. But bridge configurations vary and it is CRUCIAL to locate the correct spot for each player.
*** The pivot as described serves two purposes. 1. It gets the shaft out of the way so that you can continuously see the CTE line and 2. It helps to created a consistent bridge distance.
from SpiderWebComm (Dave Segal):
- You should never sight directly down the CTEL (center to edge line). Your head should always be on one side or the other. I like pretending the CTEL is a vertical plane - my body leans against it, one side or the other.
- The bridge position is not really correct in the diagram... it's never on the CTEL. I did it this way just for simplicity in making the diagram. My only intent is to show how the shot circle works - not the other details of CTE.
...
Consider the following:
What you see here applies to any shot until the distance between the OB and CB is less than the bridge length. I always shorten my bridge to a distance short than that between the CB and OB when this happens. Technically, a "pivot" isn't required at all - that's another story... you can step into the top of the shot circle from one side of the CTEL.
If you were to rotate the cue in the bridge as a true pivot (once again, pretend a nail is driven through the point where the cue touches the skin and into the slate), the cue would turn around the bridge circle radius. This is why people miss shots completely. You would technically only turn the cue like this on a short shot.
For the "mechanical pivoters" out there, you always place your bridge first. Once you're set in your bridge, the cue is turned along the shot circle arc, in relation to the OB - not "rotated/pivoted" from the bridge (bridge circle arc).
This is just a helpful way to describe what is really happening. This is not a functional way of playing....i.e. no one has to "see" a circle on the table in order to make any shot. This is really a "classroom" style of learning how to pivot (um, turn your cue).
OK - practical application when at the table: You should see the OB as a two-dimensional object on a vertical plane (think of the OB as a sticker on a window when down on your shot). Imagine your cue extending to the window and scrape your tip along it until you hit center ball. That's what I do. I only "see a shot circle" on very close shots - within, say, a foot or so.
Notice the longer the shot is, the bigger the circle--- the flatter the arc (think of the Earth - when you look at the horizon, it's nearly flat). The shorter the shot, the smaller the circle--- the curvier the arc (think of a basketball).
I think the reason why so many people say this is a visual system is because they "pivot to the OB" and make the shot and don't know why.
In conclusion, the "correct" center of the CB is determined by the position of the OB, always.... not by the bridge position/bridge length.
from Colin Colenso:
Any cue that moves or turns from one position to another can be described as having been pivoted at some distinct point. On CTE shots this pivot point must be behind the CB and usually it is behind the bridge hand so the shape of an arc, projected to the front of the shot circle would always be flatter than the actual shot circle arc.
Hence, it seems more like the shot circle is an approximate visualization method, like, as you've said, scraping your tip along a distant window. This is fine, but it's not very quantifiable or systematic, other than it would seem to indicate that you can intuitively sense the nature of the turn and that the turn pivots noticeably closer to the CB with closer distance shots.
Regarding edges of the OB, technically there is only one edge each side that is on the CTE line, but I understand that one's perception of variations in this edge change if one sights the various angled shots from different positions relative to the CTE line.
How does Dave's Aiming Method (DAM) work?
I first came up with Dave's Aiming Method (DAM) as a joke to mock some people that try to promote various aiming systems with outrageous claims and snake-oil-salesman type statements, but I also have some serious and useful recommendations below.
First, let's start with some outrageous claims ...
I have invented an amazing and new aiming system called DAM that will revolutionize pool playing all around the world. You won't find DAM is any books, because it has just been recently invented. But rest assured ... all future pool books will present DAM in its full glory. DAM is the best and most complete aiming system (that also contributes to correct body alignment) that has ever been devised. All of the pros use it, and it works every time for every shot, regardless of the distance between the balls, or the angle and distance to the pocket. If you ask a pro if he (or she TYP) uses DAM and he says he doesn't, it is because he doesn't want you to know his secrets. The DAM system will radically improve the shot-making abilities of those who spend the time to learn it. DAM will eventually become the "aiming standard" and will significantly accelerate your learning curve. There are those who will eventually learn the system, and there are those who will not, and be beaten by those who do. If you don't think DAM works, it is because you haven't had personalized lessons with somebody who truly understands it. I make almost every shot with this system ... I rarely miss. Isn't that proof of how good it is? Don't you want to be as good as me? If you want to master the DAM system, you must visit me in person and pay outrageous sums of money to learn all of the required intricacies. Don't ask me to describe the system in words or with diagrams, because this can't be done; although, I do have lots of fancy words and phrases I use to describe various parts of the system (aren't you impressed?). If you don't believe in my system or if you doubt the validity of my approach, you will be banished by all of my followers.
Now for a somewhat more serious and useful description ...
The basics of the DAM system are: you visualize the required "angle of the shot" and required "line of aim" while standing, you then align your cue and "center of vision" with the line of aim as you drop into your stance while keeping your focus on the object ball, then you then follow all of the recommended stroke "best practices." Be sure to maintain "quiet eyes" both at the "set" aiming position, checking both the CB tip contact point and your aiming line, and when focusing on your OB target during the final forward stroke. If you are a good shooter and maintain focus and don't do anything wrong during the entire DAM process, you will make every shot.
The key to aiming is placing the bridge hand in the exact required position so the bridge guides the cue along the necessary line of aim for the shot. Sometimes you might need to adjust your bridge position a little as you get down and settle into your stance, because you are not likely to place your hand down perfectly every time. Good shooters can see the required angle of the shot and make the necessary fine adjustments to bring the cue (with the bridge) into alignment with the necessary line. Good shooters can also make adjustments where necessary for squirt, swerve, and throw based on shot distance, shot speed, cue elevation, ball and cloth conditions, bridge length, amount and type of spin, etc.
I think good shooters use all visual information available to them to help see the required angle of the shot and the necessary line of aim. They might use any or all of: ghost-ball visualization, ball-to-ball contact-point visualization, impact-line (or "target line" or "line of centers") visualization, center-to-edge (CTE) 1/2-ball-hit line visualization, etc. Regardless, a good shooter doesn't need a mechanical "system" to do this, IMO. For not-so-good shooters, there are drills and techniques they can use to help develop their visualization skills so they can improve their ability to "see" the shot. For example, see:
- ghost-ball aiming method and drill
- NV 3.1 - Practicing contact point and ghost ball visualization
- NV 3.2 - Using the cue to help visualize the impact and aiming lines
- NV B.3 - Mike Page's aiming video (part 1, part 2)
For more information, see my October '08 and November '08 articles concerning aiming and DAM.
For seeing the required line of aim of a shot, I personally use a combination of straight intuition and feel (just "seeing the angle"), ghost ball aiming, and contact point visualization (see the videos above). Bottom line: I just visualize the aim without using any kind of fractional-ball or fixed-reference or pivot-based system.
Regardless of what I or anybody else says, the most important components for success with any aiming system are:
PRACTICE ... PRACTICE ... PRACTICE!!!
and
FOCUS ... FOCUS ... FOCUS!!!
(In other words: don't forget to aim, and keep your eyes "quiet." Also, maintain full concentration on stroke execution during the final stroke. During the stroke, you should not be second-guessing any of the stuff about the shot you should already have decided and figured out before you settle into your stance.)
Is depth perception important in aiming?
Assuming you have already visualized the required impact line and ghost ball target (see online video demos NV 3.1 and NV 3.2), aligning the cue stick with the aiming line direction does not require depth perception. (In fact, the parallax created by binocular vision, even with a dominant eye, can make straight-line sighting difficult.) Now, some people might adjust their aim while in their stance based on their perception of the "angle of the shot," impact line, contact point, and/or ghost ball target. In that case, depth perception might be helpful.
I think a low stance helps one better align the cue with the desired aiming line, without requiring too much of a shift in eye (or head) motion between the CB contact point the aiming target, while fine tuning and verifying one's aim.
For more info, see dominant eye.
from Qtec:
The difference between short and long bridge is that the EYES are further away from the QB when you play with a longer bridge. This means that when you focus on the QB or OB, you will see more of the shaft [ie. a longer line ] and therefore its easier to line up the cue on the line on the shot.
Is one's dominant eye important in aiming?
I think this is debatable, and it might vary quite a bit from one person to the next. Now, head and eye position relative to the cue can be important in perceiving the desired tip contact point on the cue ball, especially if the cue tip is not close to the cue ball when lining up a shot.
Vision and perception are too complicated and personal to simplify into a "formula" that works for all people. The focus should be on results. Each person should find the head position and sighting technique that helps them create the most accurate cue tip contact point and aiming line.
Here's an easy and free way to check visual alignment with a straight-in shot: Place the cue at cue-ball address in an elevated stance (so you can clearly see center-ball alignment and the line of the shot), then get down into your stance, without moving the cue. Alternatively, have a friend help position (and hold) the cue for you after you are down in your stance. Then move your head left and right to see how the perceived alignment and aim changes with head position. You might be able to find a head position that gives you more accurate alignment perception. The MOFUDAT drill can also be helpful.
Here's a good article that makes an argument that eye dominance is not very important in pool: "Dominant Myth?" by Bob Fancher
from JoeW:
Eye dominance is not a good or bad thing.
http://en.wikipedia.org/wiki/Ocular_dominance
It is unwise to change a person's ocular dominance, although certain occasions may necessitate this rather drastic action. The dominant eye for distance vision (six metres upwards) may not be the same eye for intermediate or near vision (2/3 metre). If no definite dominance exists, then blurring or occluding one eye is of help.
See http://www.pponline.co.uk/encyc/0148.htm
Does eye dominance matter – yes, no, a definite maybe !
http://www.sciencedirect.com/science...a6623dcb8df0af
“Binocular vision facilitates the estimation of distance, speed and angle and helps one to gain the full benefits of natural hand to eye co-ordination. If you doubt it try catching a ball with one eye shut. But, do not believe those who say simplistically that everyone should shoot with two eyes.” Lots of good stuff here.
http://www.shootinggazette.co.uk/sho..._shooting.html
And for those who want to get serious about this topic …
“Thus, it appears that there has been little advancement
in our understanding of eye dominance since
Miles (1930) concluded that “the significance of optical
dominance is not yet fully evident, although it appears
generally demonstrable as a habit”
http://app.psychonomic-journals.org/...2/310.full.pdf
from Rich93:
Set up a straight in shot and and place the cue tip right at the center of the cue ball. Now move your head until you are looking straight from the center of the cue ball to the center of the object ball. Wherever the cue is in relation to your eyes when this happens, that is where you should position your eyes over the cue.
from RSB_FAQ:
For most people, one eye is much more dominant in seeing alignments than the other. Typically, right-handers are right-eyed, and vice versa. About 5% are "cross-dominant" (e.g., right-handed and left-eyed) and some are "ambi-ocular" (no dominant eye). To aim and sight well, it helps to locate your dominant eye directly over your cue. For cross-dominants, this may call for some adjustments in stance or neck/head angles. For ambi's, the stick will be under some spot between the eyes.
Here's how to test yourself: Hold your thumb up at arm's length, visually blocking some distant object (for example, a clock or a lamp). Don't focus on your thumb; focus on the distant object. You'll see a ghost of your thumb, since your dominant eye will be in line with both your thumb and the distant object, while your non-dominant eye will be seeing past your thumb, directly toward the distant object. With one eye seeing the thumb and the other not, you get a ghost. The ghost is centered on the distant object because your dominant eye is the one that tells you what's lined up with what.
So, when you close your non-dominant eye, the thumb becomes solid instead of ghostly, since the dominant eye is looking directly at the thumb. When you close your dominant eye, the thumb appears to jump to the side because the dominant eye (that was making the thumb line up with the distant object) is not in use.
Stroke into a mirror to see where your dominance spot is, relative to your shaft. It "should" be directly over the shaft. If it's not, but you're not having difficulty aiming or sinking balls, don't worry about it.
from henho:
... there is plenty of research on eye dominance in Medline or Pubmed, a couple of thousand articles to be exact....just one for example: A new interocular suppression technique for measuring sensory eye dominance.
Yang E, Blake R, McDonald JE.Invest Ophthalmol Vis Sci. 2009 Jul 23. PMID: 19628736
Each eye supplies information to the brain differently. The dominant eye is used to fixate on objects. If you look at a point, the fixation of the dominant eye will fall on the center of the point while the non-dominant eye will fall slightly off-center. By comparing the difference between the images supplied by each eye the brain is able calculate depth information in a scene. The degree to which any eye is dominant varies from person to person as well.
In scenarios where estimating depth is important, the functioning of both eyes in tandem is vital. I don't recommend skiing with an eyepatch any more than driving. However, in scenarios where determining a straight line between two points is needed, using the dominant eye confers an advantage over using both eyes. When shooting a gun, you want to align the sight of the gun with a target. If you kept both eyes open while sighting down the barrel of the gun, when you looked at the sight you would see two targets, and when you focused on the target you would see two sights. In this scenario, the depth information your brain is supplying you is not helpful in aligning the target and sight, and it is easier to sight with one eye.
Pool is an interesting scenario in that it requires good depth perception to estimate the line of sight, generally done while standing up, and in addition requires accurately lining up the cue ball with the contact point on the object ball. If you adopt a high stance and hold the cue under both eyes, you have the best depth judgment, which is needed to estimate the speed and direction of the hit. If you adopt a low stance and use your dominant eye, you have the best ability to line up the cueball and object ball. Most people go somewhere in between, where they can line up the balls while still having a general view of the table to guide the speed of their stroke.
This seems to come into play in the nature of various cue games. In three-cushion billiards players generally adopt a more erect stance that provides a good, continuous 3-d view of the table, allowing them to accurately predict the reaction of the balls. In snooker, the accuracy requirement that smaller balls present requires players to adopt a low stance sighting down the cue. In this game moreso than in billiards, players must first estimate what will happen on the shot and determine the line of sight, then remember the layout of the table when they are down on the shot since they don't have a good view of the balls.
from JoeW:
I have created a way that you can determine the best way for you to aim and it won’t cost anything except a little time and maybe $3.00.
Photo 1 shows the table with a line drawn from the head to the foot of the table on the center diamond. I used a dressmaker’s marking pencil (cost $1.00 at Wal-mart) to draw the line. I left the pencil on the table for this photo.
For a ruler I used an 8’ piece of metal wall board corner molding ($2.00 at Home Depot). Note that the line goes from one end of the table to the other.
Photo 1
The balls are set with the base of the One ball on the line (see Photo 2) with the center of the numeral One centered on the line. If you look over the top of the One ball you can see the other side of the ball and that the number One lines up with the white line. Go to the other end of the table and set the Three ball in the same way.
The balls are now lined up perfectly. If you hit dead center on the One, stop on the Three ball the three ball should bank off the end of the table and come back and hit the One ball – a really tough shot.
Photo 2
Ok so how should you aim? Well first lets get the bridge hand out of the way. To do this I reversed the table bridge and set it where the stick will line up perfectly with the center of the One ball. See Photo 3. I am holding the table bridge with my left hand and site with my eyes and the right hand. Here is the interesting part of this technique.
As I look down the shaft and line up from the One to the Three I get what I think is a good site picture. Notice where your nose is relative to the shaft of the cue stick and this is your site picture.
Now raise up a little bit and you can see over the Three ball to the head rail and you can see the white line. If everything is lined up then you are straight for your site picture. If not, something has to change.
Shooting the shot by stopping on the Three ball and watching the return from the rail will tell you if you site picture is the least bit off. This is a difficult shot and you have to be lined up perfectly. All I can tell you is --- things will change.
Please try it. By the way, you will learn if you shoot most accurately with one eye or with two eyes.
Photo 3
BTW, I learned that I shoot "best" with the my nose slightly closer to the cue stick than I had it before using this test.
from Billy_Bob:
Here is more reading about the dominant eye...
Ken Tewksbury, Master Instructor (See #6)...
http://www.tableskills.com/article-kt2.phpRobert Byrne: "If you are having trouble pocketing balls, it may be that you aren't bending over far enough and aiming the cue like a rifle with your dominant eye."
http://www.byrne.org/pool/tips/08-1998.htmlSays Buddy Hall wrote good article on this: Billiards Digest in June 2001...
http://www.ez-shot-ghost-ball.com/dominant_eye.htmlBy Don 'The Master' Rose, BCA Advanced Instructor...
http://www.azbilliards.com/donrose/lesson4.html
double-the-distance aiming method
How does the double-the-distance aiming method work?
Here's a description from Don Smith :
"An Aiming Point Method For Pool" by Don Smith, November, 2009
Here's how it works (per the diagram below):
1. Find the point where a line from the cue ball will intersect the object ball.
2. Find the point where a line from the pocket (or other target) will intersect the object ball.
3. Estimate the distance between these two points.
4. Double this distance to find the aiming point.
Per the diagram below, Don's system recommends sighting through the center of the CB (and not along parallel lines, as implied by traditional double-the-distance and contact-point-at-center-of-ball-overlap methods). Because of this, the system doesn't work well when the CB is close to the OB (see error "E" in the diagram below), but it works fine when the balls are farther apart, for all cut angles. See the document for more info and examples.
It does take a little practice estimating the distances, but you can use your cue tip to help. See the document for more info and examples.
Jal has also done an analysis of the error with plots.
from Patrick Johnson:
Variously called "double-the-distance", "double-the-overlap", etc. It came up often in discussions of aiming systems because it's one of the few "geometrically correct" systems (like ghostball). It's OLD.
It's so well known that it's illustrated on CueTable.com's Aiming Calculator. Here's a snapshot from it. Notice the red X in the center of the CB/OB overlap
Your drawing illustrates doubling the distance from the OB's center to the contact point (and then aiming the CB's center at that doubled distance). The same method also works by doubling the distance from the OB's edge to the contact point (and then aiming the CB's opposite edge at that doubled distance). Doubling from the OB's center is best for shots fuller than half ball; doubling from the OB's edge is best for shots thinner than half ball.
finding the center of the cue ball
What's the easiest way to ensure the cue tip is aligned with the center of the cue ball?
See:
from JoeW:
I have noticed that many players begin the table aim (when they are down on the CB) by placing the tip of the cue on the table. Many players from different countries use this method as part of the aiming process and it seems there may be a reason for it. Perhaps it does help with aiming.
Apparently, when you place the stick on the table oriented through the center of the CB to the contact point, the tip is something like a pointer and you can evaluate the relative distances to either side of the CB from the center of the tip. It is easier to find center and then move relative to this place.
There is a second advantage to this method and this involves the perception of center as seen through the CB to the contact point. With the stick out of the way [there is] an unobstructed view.
There [also] appears to be a third advantage. When the stick is initially placed on the table and the center line is sought, there is a definite tendency to place the stick on this line. The use of FHE and BHE is now relative to this line of travel for the CB to OB and it is easier to determine what needs to be done relative to a line that can be visualized as opposed to an estimated line.
Are fixed-line of aim, fractional-ball aiming systems useful?
Fractional ball aiming is illustrated and described in part 2 of:
NV B.3 - Mike Page's aiming video (part 1, part 2)
Also, here's an illustration from Patrick Johnson showing 1/4-, 1/2-, and 3/4-ball hit cut shots:
Various aiming methods (even though they are not perfect) do help some people aim, concentrate, focus on the OB, stay down, and shoot better. I don't think anybody (even me) would say that is a bad thing. On the other hand, people should realize that fixed-point aiming systems with a limited number of aiming lines are not perfect and will cause you to miss shots if you don't compensate (consciously or subconsciously).
The common fractional-ball aiming system is an example of a fixed-line of aim method. It is described here and illustrated here. Basically, the claim is there are only three different aims for all cut shots: a "15-degree cut," a "30-degree cut," and a "45-degree cut." In TP A.11, I show that these aims are equivalent to 3/4-, 1/2-, and 1/4-ball-hits and the 15- and 45-degree angles are not exact. Also, I show an example shot "in between" two of the aim references to show a deficiency of the method. The method provides easy visual aiming, and it helps a player establish good reference aims for different ranges of cut shots; but for "in-between" cut angles, one must adjust or compensate between the aim references.
I know believers of these and other systems have much anecdotal evidence. In fact, if a method works for somebody, that's all that really matters. It is difficult to refute anecdotal evidence. So I'm not going to say the system don't work. I just think they are not the "silver bullets" some people think they are.
For a given shot, with N different lines of aim, assuming you can hit where you are aiming, the object ball can go only in N different directions. Depending on where a pocket is and how far it is from the object ball, the cut shot may or may not be makable with one of the selected aiming lines.
Even with English effects (squirt, curve, and throw) and cling (collision-induced throw), the object ball can still go only in N different directions for N lines of aim for a given cue stick elevation and shot speed, and for given ball and table conditions.
See TP A.13 for background and specific results. Here are some highlights:
Now, I still think the three fractional aiming references (1/4, 1/2, and 3/4) are very useful because they are very easy to visualize. And having easy to identify references is always useful (e.g., as with the tangent line and the 30 degree direction for predicting CB motion), so I agree 100% that the aim points (from fractional-ball aiming or any other system) provide a good framework from within to work, especially for people that have difficulty aiming accurately and consistently.
from Spiderman:
Like all "discrete", "fractional-ball", and similar aiming systems, it gets you in the ballpark for most shots and depends upon subconscious correction to make the fine adjustments. In other words, you have to use it as a guide, "take it on faith", and shoot the shots.
For a beginner, it will get them in the ballpark and they'll accidentally pocket more balls than by winging it. For an intermediate, they may have enough experience that they will subconsciously correct, and the system might work well for them. The expert doesn't need a system to get them in the ballpark.
All discrete systems have the same failing - they are not geometrically correct for all setups. If you claim that there are only a (small) discrete number of aim points required to hit any pocket from any setup, and disallow the subconscious correction factor, all such systems may be easily disproven. In practice, your ability to compensate overcomes the built-in flaws of the system.
Is it a foul to hit "into" a cue ball frozen to an object ball?
When the cue ball is frozen to the object ball, you are allowed to hit into the cue ball toward the frozen ball with a normal stroke. In fact there are aiming systems devised just for this type of shot (see NV B.55 and TP A.15). Examples of frozen-cue-ball shots at various angles can be viewed in HSV A.97.
Now, if there is a miscue during such a shot, it could be ruled a foul if there are obviously multiple hits or if the miscue is intentional. HSV 7.5 is an example that is tough to call, even with high-speed video.
For many example calls along with explanations, see:
NV B.63 - Instruction for pool rules quiz (part 1: CB frozen to OB)
How do you aim frozen-ball carom shots (e.g., a frozen spot shot in one-pocket)?
See:
How does ghost-ball aiming work?
The ghost ball (GB) is the imaginary position the CB must be, at contact with the OB, to make a shot. It is easy to practice visualization of the GB target by having a helper place a real ball in the desired GB location (adjusted for throw or not) and pull it away when the person shoots. I demonstrate this technique in NV 3.1; although, I didn't have a helper to remove the ball for me. Also, striped balls are useful to help the shooter visualize both the "aiming line" (from the CB to the GB center) and the "impact line" between the GB and OB centers. To me, that's the most useful advice in the video.
Here are some videos and drills to help improve your ghost-ball visualization skills:
- ghost-ball aiming method and drill
- NV 3.1 - Practicing contact point and ghost ball visualization
- NV 3.2 - Using the cue to help visualize the impact and aiming lines
- NV B.3 - Mike Page's aiming video (part 1, part 2)
For more information, see my October '08 and November '08 articles concerning aiming
In the "beginner's version" of ghost-ball (GB) aiming, throw is not considered. In more advanced GB aiming, the GB position is the exact position the CB must be at contact with the OB (adjusted for cut- or spin-induced throw) that will send the OB into the heart of the desired pocket.
There are several suggested methods to help one adjust for squirt, swerve, and throw. The required GB position is affected only by throw. The path of the CB to the GB is affected by both squirt and swerve. I suspect many top players can compensate for all of this stuff mostly intuitively (i.e., by "feel") because they have had lots of "successful experience" and lots of quality "table time." For people not so good at compensating for these factors, I and others have some suggestions and useful info here:
How many lines of aim are required to pocket a typical range of shots?
Many "aiming systems" use a limited set of alignments or lines of aim that can get you close to the right aim for a wide range of shots. However, a limited number of aims is not sufficient for a typical range of shots, unless aiming adjustments are made relative to these fixed references.
For a given shot, with N different lines of aim, assuming you can hit where you are aiming, the object ball can go only in N different directions. Depending on where a pocket is and how far it is from the object ball, the cut shot may or may not be makable with one of the selected aiming lines.
Even with English effects (squirt, curve, and throw) and cling (collision-induced throw), the object ball can still go only in N different directions for N lines of aim for a given cue stick elevation and shot speed, and for given ball and table conditions.
See TP A.13 for background and specific results. Here are some highlights:
Now, I still think fixed-reference aiming systems can still be very useful, based on the benefits listed here. The systems can provide a good "framework" from which to work, especially for people that have difficulty aiming accurately and consistently.
from Patrick Johnson:
Here's a chart showing the minimum number of aim points within 1/8 of a ball circumference (up to 45 degrees of cut angle, or half of all possible shots).
The green-shaded boxes show which combinations of pocket size and OB-pocket distance work with 15 or fewer aim points. For average size pockets (4.5 to 5.0 inches) you need more aim points when you get beyond about 4 feet from the pocket. So your estimate that "any typical shot" works is overstated, but not ridiculous. With a real aiming system, we have to double the number of aim points - an aiming system would have to have a minimum of 30 total aim points per side (left or right cut) for half of them to cover most "typical" shots.
90/90 pivot-based aiming system
What are the basics of the 90/90 pivot-based aiming system?
from Colin Colenso:
As I've mentioned before, I have been using CTE as a reference system for several months and find it better than the system I was using before which was the 'looks right' system, or basically no system at all. I've found CTE to be quite useful as a repeatable standard reference method mainly because it helps me to get a better grasp of the position of the balls in space and how this relates to my cue's alignment and the pocket.
Anyway, after my trials last night I'd say I now prefer 90/90 as a reference system to Center to Edge (CTE). The main reasons I'd say is that the ETE line is clearer than the CTE line and the pivot can take me straight to the ball park of where I need to shoot.
I'm sure I'm not doing this the same way as other guys, so don't take this as THE method for shooting 90/90 that Ron teaches.
My Method:
Firstly, I prefer to line up the actual ball edges, not the 90% from center. So a better description of what I do could be called Edge to Edge (ETE).in simple terms:
1. Lay cue tip on table in line with the edges of the CB and OB. Hold the butt end of the cue with your back hand.
2. Roughly estimate the line of aim you'll need from the standing position.
3. Slide into the bridge position pivoting where it feels right to this line of aim or cue line. This pivot can be in the air and while you're sliding your bridge, so effectively, the pivot doesn't need to be right at the bridge. It is often nearer the center and even back of the cue. You may need to shift the hip or feet slightly to get into position.
4. In the last inch or two moving toward the center CB lock in to the line of aim that feels right. Keep the ETE line in your peripheral vision during these processes.
6. Shoot.
in more detail:
1. I lay my cue down on the table. holding the butt in my right hand, such that the center of the tip is lined up with the edges of the CB and OB.
2. Observing the shot, I estimate the approximate required pivot. eg. If it's a longish shot and 3/4 ball I know the pivot will be up near the butt end. If it's a 1/4 ball from 2 feet away I know the pivot will need to be in front of where the bridge hand would go. If it's a 1/2 ball from 3-4 feet away the pivot will be near the bridge hand. I don't do exact calculations, I just try to start the following move so I know I'm moving toward the right line.
e.g. If it's a long thickish cut I pretty much hold the butt in place in the air and pull the cue across as I'm sliding it into place. If the pivot is near the bridge hand length, the bridge slides straight down the cue as I pivot the backhand across. This is the most common method. You may need to shift your hips and move your feet a little to feel comfortable.
3. While keeping the ETE line in my peripheral vision I slide my left bridge hand down the cue as I pivot the cue toward the center of the CB. The last 2-3 inches of bridge slide are in a direct line with the center of the CB and it is in this phase that I try to lock into the pot line. When I do this, I am trying to see a line from the OB to the pocket. I set the bridge when it feels right. Throughout this process I am aware of the ETE line peripherally but my eyes are not darting back and forth from the aim line to the ETE line. I try to keep my left (dominant) eye over the cue the entire time.
Negatives: Short cut shots, straightish shots and long shots are not particularly useful for me at this stage.
However, for a great many regular shots that we are used to taking on, and where seeing the pot angle is not always a given, I've found it a comfortable and very useful reference system.
If you can't slide the bridge due to the rail or an interfering ball, just visualize that procedure and try to shift the cue into the appropriate position. Usually it will be pretty close to a natural back hand pivot anyway.
from cleary:
If you break the ball up into 10% increments, you want to line your cue up so that you are aligning the last 10% of the cue ball and object ball... or as Ron V calls, 90/90.
90/90 (pocketing without side spin/english)
Pivot your HIPS to the center of the cue ball. You should now be lined up to make the shot. If you pivot past center ball, don't try to fix it while your down, just get up and start over.
from dr_dave:
The key to pivot-based systems appears to be the "pivot" and the effective center of the pivot. If you shift the bridge hand a small but critical amount during the pivot, then the resulting "line of aim" can be tweaked quite a bit. Assuming your initial alignment is consistent (for different but similar shots), and if you don't adjust your bridge during the pivot, and if you don't adjust by the exact right amount, you will miss many of the different, but similar, shots. As the diagrams in my articles show, the pivot-based systems will not work for a wide range of shots if the bridge is fixed during the "pivot" step (i.e., if the cue "pivots" about the bridge point), or if you don't use different bridge lengths for different shots. In my November '08 article, Diagram 1 shows how angle to the pocket matters, and Diagram 2 shows how distance to the OB matters. In my December '08 article, Diagram 4 shows how bridge length matters with pivot-based systems. If a "basic cut-shot aiming system" does not account for the effects in these diagrams, then the aiming system will have limited use (without intuitive compensation). After numerous conversations over the years with many of the aiming system proponents out there, and after trying everything all of the proponents have suggested to me, it is not clear to me how the aiming systems account for the effects in the diagrams. If the systems work (and they seem to for many people), they must involve adjustments that account for these effects.
What is Perfect Aim?
Perfect Aim is a method of sighting recommended by Gene Albrecht.
from Patrick Johnson:
Perfect Aim is ... Gene’s opinion that we should sight all pool shots by aligning the “inside” edge of the CB with the place on the OB where it should overlap for the cut angle we want, and that we should position the eye nearest that side of the CB directly over this line to get the truest picture of it. For instance:
- for a 30-degree cut to the left (a 1/2 ball hit), sight from the CB’s left edge to the exact center of the OB by positioning the left eye over that line
- for a 49-degree cut to the right (a 1/4 ball hit), sight from the CB’s right edge to the point 1/2 radius in from the OB’s left edge by positioning the right eye over that line
- for a straight shot, sight from the CB’s edge to the OB’s edge by positioning the dominant eye over that line (obviously, using the edges on the dominant eye side)
... Gene is a very good player with many high-level tournament notches on his belt ...
What does it mean to "quiet eyes" when aiming a shooting a pool shot, and why is it helpful?
"Quiet eyes" refers to focusing on a target with still eyes for a period of time. Studies have shown that top athletes in many sport activities (e.g., golf putting and basketball free-throws) do this. When the eyes are moving and/or are not focused long enough on a well-defined target point, line, or area, performance has been shown to be not as good. Various "quiet eye" resources can be found here:
Keeping your eyes "quiet" both in the set position (while looking at both the CB and at the target, separately), and during the final swing (while looking at the target) is important for consistency and accuracy. Pauses give your eyes time to settle and become quiet. In the set position, you want to alternately verify both the desired tip contact point on the CB (with quiet eyes) and the aiming line and target (with quiet eyes). And before starting your final forward swing (e.g., during the final backswing or backswing "pause"), you want to have quiet eyes and complete focus on your target point (e.g., the GB center, the OB contact point, a point on the rail, etc.).
What is the "conventional wisdom" and "best practices" concerning how to sight during aiming?
Regardless of what method you choose, the most important part is to be as consistent as possible for each type of shot!!! If you are consistent, you vision and brain will develop to "see" the correct line of aim for every shot.
By "where do you sight," I mean: where do you align your "vision center," which may or may not be through your dominant eye? By "vision center," I mean the head alignment that allows you to see a center-ball straight-in shot as straight, with the tip appearing to be at the center of the CB. For some people, this might be with the cue under their dominant eye (if they have one). For others, it might be with the cue under their nose, or somewhere else between their eyes. For more info and resources on this topic, see dominant eye summary and resources.
An obvious option is to always align your "vision center" with the center of the CB, regardless of the type of shot. This way, you learn to see all different shots, and how they vary, from the same perspective.
Mike Page's videos on aiming and sighting present excellent background and insights on this topic.
NV B.3 - Mike Page's aiming video (part 1, part 2)
He points out that the only sighting that makes sense for a straight in shot is over the cue along the contact-point-to-contact-point line.
He also points out that with a thin cut, the sighting line that makes the most sense is also along the contact-point-to-contact-point line (which will be very close edge-to-edge for a really thin cut).
Then he suggests that maybe you should also sight along the contact-point-to-contact-point line for all shots in between (any cut shot). He also makes a good argument that you should probably never sight along a line that is not parallel to the aiming line (which is along the cue for a center-ball hit).
Another alternative is to always align the inside eye of the shot with the inside edges of the CB and ghost ball, so you can more clearly see the ball-hit fraction (i.e., ball "overlap"). In this case, with a thin hit, you will be aligning nearly edge to edge (ETE). Some people recommend sighting exactly ETE with thin hits. An alternative here is to temporarily shift your head and close one eye to get a look at the ETE line, but then re-center your vision center over the cue during your final set and stroke.
Again, regardless of how you align and sight, the important thing is to align and sight the exact same way for each type of shot. That way your brain is seeing the same picture for the same type of shot every time.
It is also very important to find your "vision center" and make sure you align it perfectly with the cue for straight in shots.
It is also very important to make sure the cue tip is aligned with the center of the CB when you don't intend to apply English (see finding the center of the cue ball).
from Patrick Johnson:
The things you want to align for aiming (CB/OB contact points, CB/OB fractions, etc.) are rarely on the same line as your stick - they're separate lines. So when you center your vision directly over one line, the other line is necessarily off to the side a little and therefore harder to line up precisely - i.e., if you center your vision over your stick it's more difficult to be sure you're lining the contact points up precisely and if you center your vision over the contact points line it's more difficult to be sure you're lining your stick up precisely. It's a tradeoff.
So I don't think it's a given that one way is always better than the other. I'm not even sure it's necessary for a player to do it the same way every time - maybe some shots lend themselves better to one and some to the other. For instance, thin cuts and shots with lots of sidespin might lend themselves more to sighting along the contact points line, while thicker shots with less spin might be best sighted along the stick.
What's best might also change with the player - some might see the alignment better by favoring the stick while others might favor the contact points line, like how different players have different centers of vision because of eye dominance.
Is aiming a pool shot the same as aiming a rifle?
from Patrick Johnson:
Aiming a rifle and aiming a cue stick are similar, but they're not the same.Supplemental Aiming Method (SAM)
What is SAM?
The Supplemental Aiming Method (SAM) (AKA "Stick Aiming Method") is a fractional-ball aiming method taught by many BCA instructors.
from caedos:
S.A.M. is the set of aimpoints for the fractional aiming method. It is the inverse (almost exactly) of the system CJ Wiley has on his Volume 3 of 'Ultimate Pool Secrets' video. If you can roll your cue-ball in a straight line to the same point on an object ball over and over again, it will produce the same resultant path for the object ball over and over again. The contact point between the balls is not relevant to the shooter using the system, because it will happen automatically just by shooting the cue ball to the correct aimpoint. A straight shot is a #1 Aim in S.A.M. and only requires you shoot the cue ball in a line to a point on the vertical center of the object ball. This is usually done with the aimpoint being where the object ball touches the table or at the topmost part of the object ball (tougher to be precise but has better lighting). A half-ball hit releases the object ball from contact at about 30-degrees from the cue ball path (not the cue-ball to object ball line), and is the #3 Aim in S.A.M. This is the second reference for me after the #1 when I'm shooting because it has a well-defined aimpoint, the outermost edge of the object ball away from the object ball target (the pocket, most of the time). The #2 is halfway between, but uses a point on the edge of the object ball to aim at and not the body of the ball (it's tough to pick a point in the middle of a solid colored sphere); #2 releases at approximately 15-degrees. #1 is straight on, #2 is a 3/4 full hit, #3 is half-ball, #4 is 1/4 ball, #5 is 1/8 ball, and #6 is Thin. Fractional aiming has been around for a long time, and this system is another way to use it to greater effect. The #4 is hit by estimating your aimpoint onto the felt beside the object ball or by matching the #2 inside aimpoint position on the cueball to the #3 aimpoint outer edge of the object ball. #5 aimpoint is a similar estimate, and because the edges of the cue-ball and object ball are receding very quickly the penalty for error seems more extreme; I tend to leave S.A.M. for the #5 (1/8th ball hit) because I focus on the amount of ball overlap and not a point on the felt. #6 is for Thin cuts and is often taught by aiming through the contact edges of both balls and parallel shifting to the center of the cue-ball. There is no exact science that will produce a perfect aiming system. I agree with Bob Jewett when he said something to the effect of needing to know what stinks about a system before being able to use it well. What stinks to me about this system is that there is an intangible quality that appears when using the system because the subconscious mind has to be allowed to use the mind and body to make the shot look, feel, and become 'right'. This means you can say a shot is a #3 Aim all the way and maybe it's really a #3.463024 Aim or a #2.903882 Aim. If you want to play pool you will either call it a #3 and let your brain do the rest, you will use a #3 Aim as the reference and let your brain thicken or thin the hit to make it right, you will find some other way to make this system work for you, you will abandon the system for something else that makes more sense, or you will have a nervous breakdown and take up checkers because the checks taste better when the thorazine kicks in. This is a crude explanation of S.A.M. The assumption is that the shooter will use the cue stick as the pointer for the line the cue ball needs to travel down to get to the aimpoint (a specifically chosen point at the end of that line), thus making the cue-ball travel an easier task. The shooter then lets the stroke work and the cue ball has no choice but to go down the line. It's less stress. Having an aimpoint to shoot directly at removes confusion over contact points and simplifies the process so that the shooting routine completes a circuit with no loose ends and has the added benefit of a complete command structure, leading to a more focused shooter. K.I.S.S(illy).
using lights and ball reflections
Can lights and ball reflections be useful in aiming?
I think the value of this is debatable, but some people do claim it is useful. This article describes a possible approach for using reflections of lights in balls.
