Low Backspin on Skytrak!

[steve2497]

I am currently getting 2-3k backspin from a 6 iron, 3-3.5k average 7 iron, 4-4.5k average 8 iron. These averages are consistent over 000's of hits.

I have now read several posts on here about the same topic but for me no solutions seem to work.

My mat is not the issue - if I hit off a tee the same spin results
I have tried cheap range balls, TITLEIST Pro V1 and TaylorMade Golf Mens Soft Response - The balls give different backspins obviously but I am still in the above very low range brackets. The V1s give me about 1k more backspin from a cheap range ball which is expected but my spin range is just in the upper of the above numbers
I have tried low light and full lighting conditions, same result
Setup is indoors
Skytrak is level and red dot is 12 inches as expected
I have cleaned my club face ensuring there is no dirt or residue.

I have a strong grip...could that contribute? I doubt it.

My driver is not an issue as backspin is around 2k and expected for that, it is just my irons and hybrids.

Anything else I could be missing? If the above ranges are accurate for me and represent real life then I don't have an issue, I just need to know how accurate the Skytrak is on backspin so that my total distance including roll are accurate. I would test this on the range but I can only use the cheap range balls there, else loose all my expensive balls!

[3on3putt]

1.) Does the carry distance and trajectory seem accurate to real life?

2.) You mentioned that the unit is level, but have you "zeroed out" the tilt and roll? I've noticed that even 1 or 2 degrees of tilt or roll can have a fairly significant effect on accuracy (although the difference I've noticed is mostly with horizontal launch angle; haven't paid much attention to spin vs. tilt and roll).

[Morini]

Leveling won't affect spin in terms of RPM. It will affect spin axis degree for degree. Should not affect HLA (alignment does, degree for degree). Leveling will affect VLA degree for degree.

[steve2497]

Yes the distance seems about right compared to the range.

[Morini]

First of all, do you have it set to side spin or spin axis? If it is side spin, you are only seeing the backspin component, so if you have a lot of side spin, it will mean backspin numbers will be lower (mathematically). Change to spin axis.

• Great that you tested using a tee. Quick test that can identify mat issues.
• Have somebody else swing in your setup. Preferably a mid handicapper or better. If spin numbers are better, we know it is not the unit.
• If you have foot spray, I'd use it, just to see where you make contact.
• I don't think there is much you can do in terms of setup other than the usual, (clean balls, turn logo towards unit etc). Don't waste time l playing with lighting, changing the color of your socks, leveling with surveying tool etc etc. None of those will affect spin significantly.
• ST is good at reading spin, so most likely that is what is happening. If you have access to a Trackman, you could hit a few to validate.

[steve2497]

Thanks, very helpful comments. It is set always to side spin so I can see back spin and side.

My shots tend to have left spin around 400-800 giving a draw.

I don't have foot spray but impact stickers I only use on the driver, might see what comes up on the irons!

Oh and yes I didn't mention that I always have the logo facing the unit.

[Morini]

Easier if you change to spin axis. The impact of your 400-800 side spin is totally different driver to pitching wedge. For wedge, insignificant, for driver huge. Using spin axis as a measure of draw/fade, the effect is consistent club to club. Each degree spin axis moves the ball about 1.2 yards offline per hundred. You want to move a 7 iron 12 yards left to right? Need about 7 degrees spin axis.

[Morini]

Also, unlike foot spray, impact tape will lower your spin, so only use it to indicate impact position.

[GungHoGolf]

Show us all your numbers for a 6 or 7 iron. Launch angle and ball speed play a big role in generating spin. Your irons make a difference, too - GI clubs are built for lower spin/higher launch. Stick with a premium urethane cover balls (Pro V ideally) for these tests.

Also make sure you’re looking at Total spin, not backspin with a large sidespin component (toggle your interface to show total spin and spin axis by clicking on sidespin/spin axis number).

Like others have stated, SkyTrak is VERY accurate measuring spin, as long as logo is towards the cameras.

[steve2497]

Yes using v1 premium balls.

Never realised that large side spin effects the back spin numbers.

Will upload my stats now

[Morini]

Steve, I am sure you have heard this before, but there really is just one spin. The spin is on an axis. If you had 8000 RPM spin, and it was titled 45 degrees, this could be reported as 4000 RPM side spin and 4000RPM back spin. Somebody only looking at the back spin component would call that a low spin shot, but that is missing half the picture. Better to use spin axis.

[steve2497]

Here are some shots I took this afternoon, let me know any thoughts

[GungHoGolf]

What ball were you using there, and was it in good condition? Are your irons clean, in good condition, with sharp grooves?

[steve2497]

The ball I used here was Titleist Pro V1

[steve2497]

cleaned my clubs too including grooves

[steve2497]

Also even when I do not deloft, the spin is still low, see attached picture showing the skytrak shot optimizer for a 6 iron I hit at 16 degree launch which is well within acceptable for that club...

[Morini]

Yup, spin is low, no doubt about that. Usually when mat is the problem, it is low spin, high launch. Not in your case. As mentioned, it is very unlikely that ST reads wrong spin. It is just two pictures of a ball taken 4 milliseconds apart. It determines the amount of rotation and then converts to rpm. I can't see it being possible for the hardware to mess that up repeatedly and consistently.

Pretty well ruled out mat. Not likely the unit itself. What else could it be? Most likely equipment and/or swing. Easiest thing is for somebody else to take a swing in your set up. Or find another launch monitor to compare to.

[wbond]

Make certain you scrub the faces of your clubs, you will be surprised how clean they look but may actually have stuff in the grooves. Just to rule out the club portion

[steve2497]

OK I just switched on spin axis to see how total backspin increases but I don't get the maths, when you switch on spin axis the total spin rpm is not a simple add/minus of side + back rpm, I compared shots and switched on/off spin axis and I cant see how the numbers correlate:

For example, one shot shows total rpm 2640 with spin axis on (showing 19), or with spin axis off backspin rpm is 2498 with left 852 rpm. How does that work?

[Morini]

It's vectors, not simple adding. I oversimplified in the 45 degree example above. 19 degrees is quite a bit. For what it is worth, it will move the ball offline about 32 yards for a 7 iron. More hook than draw.

[Morini]

Weird, I get 557 side spin with those numbers. Either I remembered the formula incorrectly, or you posted the wrong numbers.

[steve2497]

Thanks again Morini. No I double checked the figures and can even post the screen shot but they are correct. Another one, and this is an extreme example with huge 'side spin' shows the following:

total rpm 3142 with spin axis on (showing 31), or with spin axis off backspin rpm is 2690 with left 1623 rpm.

Anyway as you say its not a clear cut case of addition or subtraction so I will just trust the numbers. When my friend is round next who is a golfer I will see what results it gives him!

[s0707]

... It is just two pictures of a ball taken 4 milliseconds apart. It determines the amount of rotation and then converts to rpm.....

I don't mean to derail the thread conversation neither doubt what you mention, but briefly: is this an official number or a number you derived/heard? I've been wondering about this lapse of time and if the processing software assumes always backspin rotation and never topspin... I say this because sometimes with my driver I hit behind the ball (i'm a mediocre golfer) and Skytrak shows something like 10k RPM backspin -- I'm guessing the ball has a bit of topspin and the software is miscalculating it as much larger backspin (if you're into science/enginnering, the nyquist issue).

[Morini]

I got that from davray666 who did some very interesting early analysis on the hardware. It is not official, and but it seems reasonable.

" Unit has 2 cameras and what looks like 2 Xenon flashes and 1 IR LED bank.
There are 2 additional sensor that are probably used to detect the ball launch and trig the camera image capture.
For each shot 3 images are captured. Time between images is
image 1 @ 0us, image 2 @ 4140us & image 3 at 10400us."

https://golfsimulatorforum.com/forum/skytrak/33189-skytrak-technical-faq

[Morini]

If we assume that the 4 milliseconds (4140 microseconds to be exact) is accurate, a 15,000 rpm shot will look like it has no spin. 1,000 topspin will look like 14,000 rpm backspin. And so on.