I want to apologize to you for what I said the other night. You don't promote your products here like some do. I had your DVD's mixed up with someone else. Johnnyt
Aiming Is Really Simple
- Thread starter Johnnyt
- Start date
I want to apologize to you for what I said the other night. You don't promote your products here like some do. I had your DVD's mixed up with someone else. Johnnyt
Johnny. No need to apologize. You're entitled to your own opinion about me, be it good or bad. Thanks for the kind words though.
Dr. Joe,
The only aspects of the collision that I'm aware of which might increase the resultant (net, effective) physical cut angle beyond what geometry dictates are:
1) topspin imparted to the OB, which only reduces effective throw ever so slightly;
2) rotation of the tangent line due to the finite (non-zero) duration of the collision.
Both effects, according to calculations derived from measurements of related entities (e.g., contact time, friction), are very small compared to, say, throw. Item #2 would probably require a fairly fast shot at a large cut angle to have any hope of noticing its effect.
I applaud you for sticking to your test results. Real world phenomena hold sway over theory. It's just that the discrepancy seems to be so large that it's hard to believe that someone else wouldn't have noticed it before. You may want to examine some of Dr. Dave's high speed videos to see if you can locate any supportive evidence.
Jim
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Patrick,
Thanks for the table. The numbers I checked are accurate (if I may judge) and I think it, along with Dr. Dave's diagrams and what some of the other posters have said, tells the story...unless something very unexpected is going on!
If you calculate the error in the impact line direction, as shown in Dr. Dave's diagrams (posts #95 & #98), you get slightly smaller numbers at typical CB-OB separations than your table might suggest. The differences between cut angle error versus impact angle error is greater the closer the balls are to each other, with cut angle error always being larger. I think the impact line is a better reference, at least in principle, since it directly defines the desired geometric OB direction (presumably adjusted for throw), and is independent of CB-OB separation. I'll admit, though, it is a nitpick other than when the cueball is within about 6" or so of the OB.
Jim
You lost me on that curve, Jim. What is "cut angle error versus impact angle error" and how does it change with CB-OB separation?
I believe the errors I described are independent of CB-OB separation (maybe you're not saying otherwise?).
pj
chgo
He might be referring to the effects here:
Regards,
Dave
PS: Did you see how nice Spidey was earlier when I asked him to be nice to you. I look forward to more civility in future Spidey-PJ exchanges. :grin-loving:
Why would you even instigate? PJ/I only REALLY butted heads once ever. You seem to position yourself as the peace keeper, but you like to drop snide "aiming system believers" comments yourself (which I know are directed at me). Which, by the way....I'm not a believer, I'm a "knower."
If you wanna learn more about my feelings on the subject, you can go *HERE*
I didn't mean to instigate. I was actually giving you props for being civil and admitting you and PJ agree a lot. This wasn't evident to me in many past "uncivil exchanges," IMO.
I joke about your "Just align and pivot, and the ball goes in the whole" but I rarely have you in mind specifically when I generally mock the outrageous claims made by many "systems proponents" that have posted here over the years. I try not to mock individuals ... only outrageous claims. I'm sorry if you felt I was picking on you. I do have respect for both you and PJ. Both of you often make good contributions on the forum.
Regards,
Dave
Patrick,
It really isn't that relevant to the sort of shots Dr. Joe has been describing, but I just wanted point out a minor difference in how the error might be calculated.
For the record (I know you know), cut angle is defined as the angle between the cueball's pre-impact direction (aim line) and the object ball's post-impact direction (toward the target). Both directions are defined by the positions of the CB, OB and target (pocket). The impact line is more of an absolute, in that if you move the CB closer to the OB along the their line of centers, the required cut angle changes, but not the necessary impact angle (measured with respect to the CB-OB line). So if you figure an error (e.g., from aiming at the contact point instead of the ghost ball center), you get slightly different numbers at typical CB-OB distances (they're identical at infinity). Both errors are dependent on the separation.
For instance, suppose you need to drive the OB 30 degrees off the CB-OB line of centers. With a separation of 36", aiming at the contact point generates a 16 degree error in impact direction, and a 17 degree error in cut angle. At 6" of separation (between CB-OB centers), the corresponding errors are 19 degrees and 28 degrees, respectively. So the differences are pretty large at these distances. Since it's the error in the impact direction that determines whether or not a shot is successful, the distinction becomes significant at close separations. The numbers are based on the geometry and ignore throw.
Jim
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Jim, I understand your terminology now:
"Cut angle" = angle formed by CB path and OB path
"Impact angle" = angle formed by line of CB/OB centers and OB path
Thanks.
pj
chgo
"Cut angle" = angle formed by CB path and OB path
"Impact angle" = angle formed by line of CB/OB centers and OB path
Thanks.
pj
chgo
Yep, you read enough of this stuff and you'll miss a lot more. Trust me. Johnnyt
Patrick... You wrote this a few posts ago and I wanted to discuss it.
Does this VERY SIMPLE description help in any way for us laymen to pocket balls better... In other words, can we think to ourselves "okay... I see the actual contact point being the point on the OB furthest away from the pocket... good." "Now I am going to cut it in (at whatever angle I have) and I'm going to aim at X, or halfway to X or some such thing." where X = some point between that contact point and something else...
You know... playing pool for years and am pretty good, and I'm not really sure I knew the full extent of that very simple description...
Anyone care to elaborate?
Does this VERY SIMPLE description help in any way for us laymen to pocket balls better... In other words, can we think to ourselves "okay... I see the actual contact point being the point on the OB furthest away from the pocket... good." "Now I am going to cut it in (at whatever angle I have) and I'm going to aim at X, or halfway to X or some such thing." where X = some point between that contact point and something else...
You know... playing pool for years and am pretty good, and I'm not really sure I knew the full extent of that very simple description...
Anyone care to elaborate?
On a 30 degree cut shot, the contact point from the shooters perspective is going to be 1/4 ball, half way between center of the OB and the edge of the OB. In order to make contact at that point, the shooter must aim through the center of the cue ball to the edge of the OB. This will cause the CB to hit the OB at the contact point.
Steve
Steve
Okay, what about anything other than a 1/2 ball hit where you are not aiming at the edge of the OB. I'm talking about applying some universal principle for ALL cut shots... Maybe it's just my own ignorance... but I think this might help.
If possible, please put it into terms.. "So I see the contact point there... Now I get down to shoot and I aim at X" (which I'm assuming is halfway between the contact point and some other point). I think this might be the secret we are all looking for.
Speaking on behalf of myself... I can see the contact point very well, as I'm sure everyone else in the world can. I can also deliver my cue ball to a specific point very well, something a small minority are as good at. But I think the spot at which I am aiming has not been accurately solidified in my mind very well, which is why I miss the shots I do. Because these are more done by feel than anything else. (ie... umm.. that looks a little too full, that looks too thin.. um... okay just right)
If possible, please put it into terms.. "So I see the contact point there... Now I get down to shoot and I aim at X" (which I'm assuming is halfway between the contact point and some other point). I think this might be the secret we are all looking for.
Speaking on behalf of myself... I can see the contact point very well, as I'm sure everyone else in the world can. I can also deliver my cue ball to a specific point very well, something a small minority are as good at. But I think the spot at which I am aiming has not been accurately solidified in my mind very well, which is why I miss the shots I do. Because these are more done by feel than anything else. (ie... umm.. that looks a little too full, that looks too thin.. um... okay just right)
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Funny you should ask this, because for the last month I've been wanting to post something somebody sent me recently. Your message helped me decide to do it sooner rather than later. The "something" is an aiming method that helps you figure out the aim point fairly simply. It is presented in a new thread entitled double-the-distance aiming method. Check it out, and let us know what you think.
Thanks,
Dave
Thanks,
Dave
I read the post and your link... and in theory it looks good. Its application will have to be tested at the table. I supposed doubling the distance is nearly the same as "half-way between point X & Y, so I'll see if I can do the transposing in my head to make it make sense to me that way. Or, I may be just reinventing the wheel and might just be better off using the DIM method. Dunno, I'll have to check it out.
At any rate, great post. I can't believe that after all these years of playing pool I still have a hard time imagining the AIM point vs. the Contact Point. Now I know why I miss my combinations so often, because I've been picking a point on the object ball to hit and have failed to remember that the cue ball is round too and have misjudged the aiming. I feel like an idiot. It just goes to show how much we actually DO play by feel. It's amazing I'm anywhere near as good failing to recognize this very simple aspect.
At any rate, great post. I can't believe that after all these years of playing pool I still have a hard time imagining the AIM point vs. the Contact Point. Now I know why I miss my combinations so often, because I've been picking a point on the object ball to hit and have failed to remember that the cue ball is round too and have misjudged the aiming. I feel like an idiot. It just goes to show how much we actually DO play by feel. It's amazing I'm anywhere near as good failing to recognize this very simple aspect.
Aiming
Its obvious everyone wants to defend "their method". I see as two battles, you are either a cut system person or a aiming line person. How you arrive to the next shot is where you start to separate the abilities of the two. Unless you have the ability to use English to its full extent ball pocketing ability is of limited good to you. No one will continue to run the table with low percentage shots as their portion of table position. I would say to everyone to choose their method based on how far they are able to take their games. How many pros stand up and say: Hey Im a cut system person exclusively. There you go!
Its obvious everyone wants to defend "their method". I see as two battles, you are either a cut system person or a aiming line person. How you arrive to the next shot is where you start to separate the abilities of the two. Unless you have the ability to use English to its full extent ball pocketing ability is of limited good to you. No one will continue to run the table with low percentage shots as their portion of table position. I would say to everyone to choose their method based on how far they are able to take their games. How many pros stand up and say: Hey Im a cut system person exclusively. There you go!
Well sure... but the whole point is, if visualizing the ghost ball was so easy, then everyone would be world-beaters in pool. It's more like trying to find a way to aim that is easier than trying to visualize a 3D ghost ball in air & space, which is difficult to do.