Quote Originally Posted by gamincurieux View Post
Which is more important to be aligned? I would have thought that as long as the lens is aligned it shouldn't matter about the neg carrier.... am I right?
The lens axis and negative have to be perpendicular. The baseboard alignment is secondary. At very big magnifications (16x20 etc) the baseboard can be an inch off and it will still be fine, however, the negative to lens alignment needs to be nearly as accurate as that of a 35mm camera body.

This may also help: http://www.apug.org/forums/forum41/5...endicular.html