Originally Posted by StoneNYC
Are all the lens threads the same size? I already have a 135 from another enlarger, but that's for 6x7 right so for 4x5 I need 150mm?
The three most common thread sizes are 25mm, 39mm, and 50mm. http://www.durst-pro-usa.com/lensboard.php?tab=3 gives a pretty good list of lenses and their corresponding thread sizes.. By far the most common is the 39mm.