Henry, that's it exactly. The two bellows sets combined are so thick that they won't compress enough to get a 50mm lens to work correctly. A recessed lensboard might work, but it'd need to go up into the enlarger about two inches. Edit: You could also leave the bellows exactly as they are-don't combine the two sets. This will just work, but only with a 135mm lens and you will also have to flip the mount for the focusing stage around to drop the lens down just a bit. A 150mm lens will be too long.
One other issue is the brightness of the lamphouse. When you go from the big surface area of 4x5 down to 35mm, the physical size of 35mm film and the smaller opening in the negative carrier drastically reduces the amount of light available--instead of having all of the light from the head to illuminate the film you're now only using a small amount that goes through a narrow opening in the middle. If you have a 4x5 color dichroic or cold light you may have experienced this when swapping out 4x5 to medium format to 35mm negative carriers. Color heads sometimes have interchangeable 35mm mixing chambers/boxes that really help with this.
Last edited by konakoa; 02-16-2013 at 02:26 PM. Click to view previous post history.
Reason: Added info.