View Full Version : Bellows/Lens

Jarrell Conley
17-Sep-1998, 16:36
Pardon any dumb questions I may ask since I'm completely new to L F. I'm trying to understand the relationship, if any, to bellows extentions and lens focal len gth. I read about bellows extentions alot here, in my few days of visiting this site. I also am thinking seriously about moving up to LF, but really don't know where to begin. I've noticed 2 or 3 Brand/models of starter cameras keep showing up, which probably means they're all pretty good. Does any of these accept 120 roll film backs.

Ron Shaw
17-Sep-1998, 17:15
I think most any LF camera can take a roll film back, however, I think if you wa nt to use roll film, make it easy on yourself and use a MF camera. If Im going t o the trouble of LF, I want that LF negative! LF cameras use a bellows to couple the lensboard to the back. You have seen these, and there is a limit on how muc h you can 'stretch' them. If you mount a 150mm lens, for instance, you must rack out the bellows approx. 150mm when focused at infinity. If you mount a 300mm le ns, you must rack it out a corresponding amount. At some point you reach the lim it of your bellows. Keep in mind that as you focus closer than infinity (as is u sually the case), you must also rack out the bellows. The camera you choose must have a bellows that will handle the lens you need. Most field cameras have 'dou ble extension bellows', which means it will rack out twice the distance required to focus a 'normal' lens to infinity. (for instance, a normal lens for 4x5 is 1 50mm, so a double extension bellows should rack out to 300mm, which will give yo u 1:1 with that 150mm lens.)