let’s say you have a canon 550D with a “22.3 x 14.9 mm CMOS sensor”
http://www.dpreview.com/reviews/canoneos550d/page2.asp
and a 50 mm lens
then you would set your film gate to 22.3mm and your focal length to 50mm
hope this helps! 
let’s say you have a canon 550D with a “22.3 x 14.9 mm CMOS sensor”
http://www.dpreview.com/reviews/canoneos550d/page2.asp
and a 50 mm lens
then you would set your film gate to 22.3mm and your focal length to 50mm
hope this helps!