frame rate

[Jim Nelson]

Hi,

 

Can someone please help me out?

 

Will changing the frame rate have an effect on the exposure? For example, if we go from 24fps to 45fps will we have to change our fstop?

 

 

 

Thanks for your help

[David Mullen ASC]

Yes, of course it affects exposure... if the film or sensor is running twice as fast, it's only being exposed for half as long, though with a digital camera, you have more shutter speed options to compensate for the exposure loss. Ultimately the issue is shutter speed or time. With a 180 degree shutter at 24 fps, the exposure time is 1/48th. With a 180 degree shutter at 48 fps, the exposure time is 1/96th. However it is possible with a digital camera to switch from 24 fps to 48 fps but keep the shutter time at 1/48th for both (basically a 360 degree shutter at 48 fps, i.e. no shutter).