Just so I Understand

[Dan King]

Hey Folks. Just so I'm clear on what some of the numbers mean in ST practice mode on the range. If I hit a shot that indicates 0 side spin (center) and 0 side angle, in theory that shot should go straight down the center of the white markers with 0 offline yardage indication correct ? Consequently, if I hit a shot with side spin (right or left) and the side angle is 0 that tells me I've hit a true fade or draw from center. Just want to make sure I understand what ST is telling me regarding my shot analysis.

If I'm correct regarding 0 side spin/side angle and my shot is off center, is that an indication that my ST isn't aligned perfectly perpendicular to the screen? Also, I would think if I had 0 side spin but maybe 2 degrees side angle, that indicates a push or pull. Am i getting this correctly?

[wbond]

Those numbers aren't truly zero, when you go into shot history, you will usually see some spin so it may be slightly off the centerline. You are understanding the readings correctly.

[Dan King]

Those numbers aren't truly zero, when you go into shot history, you will usually see some spin so it may be slightly off the centerline. You are understanding the readings correctly.

Thank you, good to know. Makes sense because I tried to move my ST for alignment based on the 0/0 scenario and it's never perfectly on center so there must be some side spin on every shot.

[wbond]

Yep, it shows up on the shot screen. I never paid enough attention to figure out what their threshold was for reporting spin and HLA. i.e. less than 200 side spin will be 0 or something along those lines.

[Morini]

Don't know about side spin, but ST seems to read all shots between +- 1.8 degrees as zero side angle. There is a thread on that here:
https://golfsimulatorforum.com/forum...-degrees/page2

I think this is just a limitation of measuring HLA from a perpendicular position. There are two photos of a golf ball. The size difference is used to determine HLA. If you think about it, the more angle, the more the ball changes size in second image. Between 0 and 1.8 degrees, the ST can't tell the difference.

If we assume that the ball travels 10 centimeters downrange between photos, a 1 degree negative HLA would have moved ball 1.75 mm away. 2 degrees 3.5 mm. 3 degrees 5.25 mm. And so on.

1.75 mm from 250 mm away (distance from sensor to ball) is 0.7 percent smaller. Probably not detectable in a the smallerish resolution of the ST sensor.

To make a long story short, zero HLA is plus or minus 2 inches when it hits your screen, or 3 yards on your virtual 100 yard shot.

I don't know what the minimum threshold is for spin axis, but would be interested in finding out.

[SkyTrak_Seth]

On the practice range, we display "CENTER" when the side spin is less than 150rpm or the side angle is less than 1.5 degrees. If you go into the shot history table, you will see the actual value listed there. A reading of true zero is rare, and may indicate a misread. Just as a note, the alignment of the unit will affect the actual/displayed readings, particularly for side angle. So there's no instance where you would get a zero side angle but the ball shoots off to one side due to alignment - if it were out of alignment, the push/pull reading would be off compared to what you are actually hitting.

[Gresh12]

Seth I see a lot of actual zeros on HLA in my data but I never see 0.4 or -0.4. I seem to either get exactly 0 or + or - 2.0 or more.

I’ve really started to wonder about the HLA of my unit the last while. I hung a towel in the middle of my net that is 1 ft wide. I’m 6 ft from the net roughly and I can hit the towel and see shots start with HLA that can’t be correct based on the maximum angle that still hits the net at my range.

[Dan King]

Don't know about side spin, but ST seems to read all shots between +- 1.8 degrees as zero side angle. There is a thread on that here:
https://golfsimulatorforum.com/forum...-degrees/page2

I think this is just a limitation of measuring HLA from a perpendicular position. There are two photos of a golf ball. The size difference is used to determine HLA. If you think about it, the more angle, the more the ball changes size in second image. Between 0 and 1.8 degrees, the ST can't tell the difference.

If we assume that the ball travels 10 centimeters downrange between photos, a 1 degree negative HLA would have moved ball 1.75 mm away. 2 degrees 3.5 mm. 3 degrees 5.25 mm. And so on.

1.75 mm from 250 mm away (distance from sensor to ball) is 0.7 percent smaller. Probably not detectable in a the smallerish resolution of the ST sensor.

To make a long story short, zero HLA is plus or minus 2 inches when it hits your screen, or 3 yards on your virtual 100 yard shot.

I don't know what the minimum threshold is for spin axis, but would be interested in finding out.

Well, I appreciate the scientific answer. That would explain the variance down the center with 0/0 readings. I'll check out the thread, thank you Morini.

[Dan King]

On the practice range, we display "CENTER" when the side spin is less than 150rpm or the side angle is less than 1.5 degrees. If you go into the shot history table, you will see the actual value listed there. A reading of true zero is rare, and may indicate a misread. Just as a note, the alignment of the unit will affect the actual/displayed readings, particularly for side angle. So there's no instance where you would get a zero side angle but the ball shoots off to one side due to alignment - if it were out of alignment, the push/pull reading would be off compared to what you are actually hitting.

That makes sense, thank you Seth.