Can anyone tell me what lens size would be needed for enlarging a 6x7 negative? Also, will that lens be ok for enlarging 35mm, 6x6 and 645? I want to start enlarging but don't want to spend a FORTUNE on too many lenses if possible.
Some, but not all, 80mm enlarging lenses will cover 6 x 7, but usually just barely. 90mm is preferable, but there aren't as many 90mm lenses around as one would like. Anything longer will work fine, but the longer the lens the more limited the enlargement size. 75-80mm is the "normal" focal length for 6 x 6, but, again, it will limit your enlargement size with 35mm.
With a 90mm?? I don't know how much extension that particular enlarger gives, so I'm just guessing. I imagine the most you could manage from 35mm would be an 8 x 10, but the limit may be smaller.