Shutter angles to use with 60p, 48p, 36p, etc.....

[casey warren]

I was wondering what the normal (/highest quality and most crisp motion) shutter angles are to use with the various frame rates on the HVX. So far I have been just doubling them, for example for 60p i use a shutter angle of 120?, so I can get nice crisp motion. However, I was wondering if there is any standard that you are supposto use when variying frame rates. (like how 24fps should normally use a normal shutter angle 48?)?

 

[khmuse]

A constant shutter angle will result in the same effective relationship between frame rate and shutter period over any range of frame rates. If you were changing shutter rate and not shutter angle, then your approach would be valid in that it would maintain a 180 degree shutter angle.

If you were shooting 24 fps with a 1/48 of a second shutter period, this would be the equivlent of a 180 degree angle. 1/ (24 fps x (360/180)) = 1/ (24 fps x 2) = 1/48

If you were shooting 60 fps with a 1/120 of a second shutter period, this too would be the equivlent of a 180 degree angle. 1/ (60 fps x (360/180)) = 1 / 60 fps x 2) = 1/120

However, if you take your approach and double the frame rate to calculate your shutter angle, you end up with shutter periods that become very non standard.

Shutter period and shutter angle are different ways of expressing the same thing, the advantage to an angle unit of reference is that it maintains a constant relationship to the frame rate.

What should be understood is the effect that changing the shutter rate / angle has on the resultant image.

As the period decreases (angle decreases) the light received by the imagers decreases and relative motion will have less blur effect.

Conversely, as the period increases (angle increases) the light received by the imagers increases and the relative motion will have more blur effect.

The range of angles that is "typical" in film cameras is between 140 - 210 degrees with 180 degrees being one of the most common.