View Full Version : Frame height--UGH

01-13-2010, 09:04 PM
Hey all!

Can anyone explain the relationship of the frame height of a camera and its focal length? I feel stupid asking this, but I can't seem to get it.

Also, can anyone tell me how to determine the frame height value for a given camera? Pleeeeeassse???


01-13-2010, 10:28 PM
The frame height is the height of the film, or the height of the sensor if the camera is digital (measured as a distance, not in pixels). Actually, to be slightly more precise in the LW case, it is the height of the exposed area of the film or sensor.

The relationship with focal length is:

focal length = zoom factor * frame height / 2


01-19-2010, 10:22 AM
I looked up the dimensions of the sensor in the DSLR I was using--after I dialed that in, the scene fell into place! Thank you much, sir. :)

Captain Obvious
01-19-2010, 10:55 AM
Please note, though, that the frame WIDTH is calculated from the frame height * aspect ratio. So if you set up a 24 mm frame height (normal still camera film) and the aspect ratio is 2:1 (so 2000 by 1000 pixels resolution with a 1:1 pixel aspect ratio, for example), the width of the frame will be 48 mm, a fair bit bigger than the 36 mm of normal still camera film.

01-21-2010, 12:28 AM
Dudes, awesome. Cheers.