shutter speed

[Jim Nelson]

Hi,

 

I heard somewhere, that in film you don't have shutter speed, you can only adjust the shutter angle. Wherease in digital, you can only adjust the shutter speed and not the angle. Is this true?

[David Mullen ASC]

Hi,

 

I heard somewhere, that in film you don't have shutter speed, you can only adjust the shutter angle. Wherease in digital, you can only adjust the shutter speed and not the angle. Is this true?

 

No, you always have a shutter speed (TIME) -- the length of the exposure per frame -- it's just that on a film camera, shutter time is controlled by the shutter angle + the frame rate. The shutter is a spinning disk with a portion removed to allow the frame to be exposed part of the time, so if the shutter angle is 180 degrees, i.e. a half-circle, then the gate is closed 50% of the time since 180 degrees is half of 360 degrees. So at 24 frames per second, with the film in the gate for 1/24th of a second, it is being exposed for half that time, 1/48th of a second. So that's the shutter speed, i.e. shutter time, exposure time, etc.

 

Digital cameras generally don't have a film-style rotating mechanical shutter, you just set the time you want the sensor to collect a charge and transfer it, though some cameras like the Red One allow you to set a "shutter angle" instead of a time for those that like to do that. The advantage of setting a fake "shutter angle" figure in the digital camera is that the exposure time automatically changes when you change frame rates.

[Jim Nelson]

Thank you very much for your help :)