Quote Originally Posted by Sparky View Post
Although what confuses me about that is - I always understood that ever doubling of a bellows length implied a doubling of image size (and quadrupling of exposure of course)... but in the case of a 55mm lens - 1:1 gives you 110mm and therefore 2:1 gives you 220mm 4:1 is 440mm etc... which doesn't seem to jive with the above formula!
Doubling the focal-length only applies to a magnification of 1