Posted by Les on October 28, 2000 at 12:20:44:
In Reply to: Re: Bellows extension? posted by Kent on October 28, 2000 at 10:21:08:
A lens of normal design, lets say a 10" Tessar,
will need to be 10" away from the film (or 10" of
bellows extension) to focus AT INFINITY.
It will need more bellows to focus closer.
Telephoto lenses break this rule. a 10" Telephoto lens will need less than 10" to focus at infinity, but will something more than it's infinity bellows to focus closer. This is why on a 4x5 Pacemaker with a bellows extension of 12" I can barely focus my 12" Commercial Ektar at infinity, but can focus my 15" Tele-optar down to about 15 feet.
This is usually a new concept for people moving from 35mm to large format, because in 35mm ALL long lenses are telephoto, because they can't vary the thickness of the body like we can on a bellows camera.
If you want to know how it's done write back and I'll give a brief explanation, but I don't want to add to an already swimming head.