Dimensional difference between 35 mm and medium format enlargers. Is it all about the bellows?

I am planning to upgrade my Beseler printmaker 35 to be able to print medium format negatives,

specifically 6 x 6 negs. I know there is a upgrading kit commercially available from Beseler. After I found

the condenser glass in EBAY and called the store to be sure it was the one that would fit my Head, the

guy told me that this would'nt be a good idea because the Beseler 35's dimensions, even after upgrading

the lens to 75mm and applying the right condenser glass would cause vignetting problems. He

recomended and offered to look for an available, used, medium format head that would fit my chassis. My

questions are:

1. The glass that fits the beseler 35 is the same as the one for the beseler 67 (which is made for both 35

and mf.). If the gentleman that helped me is correct, what is the dimensinal difference between the two

products that causes vignetting problems in the beseler 35? Is the bellows dimensional difference is what

would cause the vignetting? Is it some difference in the dimension of the box or light quality?

2. Is it relatively easy to find/install a different head unto my beseler chassis?

3. What is the difference in quality of print if I use a 75mm lens as opposed to a 80mm for med. format?

4. The upgrade kit the beseler sells has two exact condenser glasses to be placed in the head. I currently

use only one for 35mm (that is the way Adorama sold it to me, new). Will there be problems with using

only one for medium format if I decide to go with my own printmaker 35 head?

Thank you all for your help!!

The ways you get vignetting are improperly placed lamps in relation to the condensers or

condenser sets being too small a diameter for the negative size,

If you have proper condensers and enough of the are exposed to the full neg is exposed,

there should be no vignetting. It does not matter if the corners of the condenser is cut

off so long as the full neg is exposed. Check to make sure nothing blocks the light in

the 6x6 area.

If the bellows is long enough to focus the longer lens for small pics, that will be ok.

Either 75 or 80mm lenses will work. Most better quality lenses are 80.

A quality 23C or other med format enlarger would be a better investment. The

printmaker is strictly an amateur machine built to the lowest possible function standard.

It will work, but like an airplane-car, it won't be a great 35mm enlarger or a great 6x7 enlarger. The column on that model is OK for 35mm but the extra weight of the bigger condensers will make it less stable.

You shouldn't get any more vignetting than the 67XLC, for instance (it has the same sized holes (aka filter holder) for the light to get through) but if you're getting serious about the craft a used 23C or better is definitely the way to go. I always preferred 4x5 enlargers for MF and even 35mm myself, so you might consider something like that.

Don't waste your time scratching around for an upgrade kit, since used darkroom gear is practically being given away nowadays. Look around for an LPL 7700 enlarger (Also sold under the Kaiser, JOBO and yet another name in the US I believe). Whatever brand it's sold under, it always has the number 7700 in the name. This enlarger does all formats from 35mm to 6x7, and does them superbly. I bought mine over 20 years ago, and I've never regretted it.

I also concur that the better enlarging lenses come in an 80mm focal length, rather than 75mm. Again, prices are so low that it really isn't worth compromising on quality. Rodagon, Componon-S and the 6 element El-Nikkor are the ones to look for. Anything less, and you'll find yourself upgrading again sooner or later.