Difference between revisions of "Measure Rev Rate"
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| − | + | {{Howto}} | |
| − | Tape from PAP to above fingers. | + | Calculating Rev Rate requires a video. |
| + | |||
| + | Place Tape from PAP to above fingers. | ||
| + | *Make sure the tape is contrasting in color to the ball. This will allow you to easily see the rotations. | ||
Film a few throws | Film a few throws | ||
| Line 9: | Line 12: | ||
On a frame-by-frame player (Quicktime) count the number of times the tape revolves over 10 frames. | On a frame-by-frame player (Quicktime) count the number of times the tape revolves over 10 frames. | ||
Be as exact as possible with this calculation. | Be as exact as possible with this calculation. | ||
| − | 1/4 rotation over 10 frames is equivalent to 45 RPM, so a minor mistake in reading the video can be large | + | |
| − | To minimize error, throw more than one shot, and average your results. | + | |
| − | The higher the video quality, and the higher the frame rate, the more exact results you can obtain. | + | *1/4 rotation over 10 frames is equivalent to 45 RPM, so a minor mistake in reading the video can be large |
| + | *To minimize error, throw more than one shot, and average your results. | ||
| + | *The higher the video quality, and the higher the frame rate, the more exact results you can obtain. | ||
| + | |||
A short duration such as 10 frames is best, as this allows you to remove many effects of the lane such as friction. | A short duration such as 10 frames is best, as this allows you to remove many effects of the lane such as friction. | ||
| + | |||
You will end up with | You will end up with | ||
| Line 20: | Line 27: | ||
At this point, it's simply conversion factors from high school science class: | At this point, it's simply conversion factors from high school science class: | ||
* I am using 30FPS, as most video cameras in the US will use this * | * I am using 30FPS, as most video cameras in the US will use this * | ||
| + | |||
(x Revs / 10 frames} x (30 Frames / Second) = (revs / Second) | (x Revs / 10 frames} x (30 Frames / Second) = (revs / Second) | ||
(Revs / Second) (60 Seconds / 1 Minute) | (Revs / Second) (60 Seconds / 1 Minute) | ||
| + | |||
Multiply X Revs by 3, (or multiply by 30 and divide by 10) | Multiply X Revs by 3, (or multiply by 30 and divide by 10) | ||
The Multiply your result by 60. It's pretty simple! | The Multiply your result by 60. It's pretty simple! | ||
| + | |||
For example: | For example: | ||
If the ball Completes 2 FULL rotations only over 10 frames | If the ball Completes 2 FULL rotations only over 10 frames | ||
| + | |||
2/10 * 30/1 * 60/1 = 360RPM | 2/10 * 30/1 * 60/1 = 360RPM | ||
| + | |||
| + | ==Video== | ||
| + | Video Courtesy of JustinWi<br /> | ||
| + | {{#ev:youtube|pkcvF_M1SaU|640}} | ||
| + | |||
| + | |||
| + | [[Category: Bowler Measurements]] | ||
Latest revision as of 12:56, 15 February 2013
 |
This article is a how-to guide detailing a practice or process. |
Calculating Rev Rate requires a video.
Place Tape from PAP to above fingers.
- Make sure the tape is contrasting in color to the ball. This will allow you to easily see the rotations.
Film a few throws
TAKE NOTE of the Frames Per Second you're recording in. Most video cameras are either NTSC-30FPS or PAL-25FPS, but other rates do exist.
On a frame-by-frame player (Quicktime) count the number of times the tape revolves over 10 frames. Be as exact as possible with this calculation.
- 1/4 rotation over 10 frames is equivalent to 45 RPM, so a minor mistake in reading the video can be large
- To minimize error, throw more than one shot, and average your results.
- The higher the video quality, and the higher the frame rate, the more exact results you can obtain.
A short duration such as 10 frames is best, as this allows you to remove many effects of the lane such as friction.
You will end up with
X Revolutions / 10 Frames
At this point, it's simply conversion factors from high school science class:
- I am using 30FPS, as most video cameras in the US will use this *
(x Revs / 10 frames} x (30 Frames / Second) = (revs / Second)
(Revs / Second) (60 Seconds / 1 Minute)
Multiply X Revs by 3, (or multiply by 30 and divide by 10)
The Multiply your result by 60. It's pretty simple!
For example:
If the ball Completes 2 FULL rotations only over 10 frames
2/10 * 30/1 * 60/1 = 360RPM
Video
Video Courtesy of JustinWi
