Beseler 23cIIIXL Focus travel issue with 135mm lens

[DaveFred]

First time poster here.

Recently bought a Beseler 23c III XL with the 23cIII variable contrast head. This is a diffusion head that is designed to be used without the upper bellows and sit on top of the negative carrier, from what I have gleaned. Part of what I am doing is figuring out what is set up right, what isn't; what works, and what needs repairing. It came out of the public school system here.

I am familiarizing myself with it a bit. I used Beseler 45MXT Dichro units a lot in college, but it was in a pretty idiot proofed darkroom.
I have a 135mm Schneider lens. Today I ran into an issue with focus travel using the 135mm lens. As in, I couldn't get enough travel out away from the negative to get the image sharp. I kept hitting the end of the rail. I was trying to print 6x7 ish (two 35mm frames with a improvised negative carrier). I tried this at different heights away from the base board. Ended up using a 60mm. and it worked ish. Not sure if there was drop off, but it was fine for what I was doing.

My question
Is there an adjustment for how much travel the lower bellows gets? I see some allen set screws that look like likely suspects, but also it seems like they would be integral to alignment stuff. It seems like I only need to be able to raise and lower the head enough to get the negative carriers in and out, so in theory all of the travel rail could be slid down as I dont need to adjust for negative size like a condenser head. I'm thinking maybe this adjustment was never made by previous users as they only printed 35mm.

Does this make sense to anyone? Has anyone ran into this issue with diffusion heads on 23cs?

 

[MattKing]

Welcome to Photrio.
I don't have an answer for you, as I've only used Beseler 23C enlargers, never set one up, but wonder if the 135mm lens is too long a focal length.

 

[GregY]

DF, I don't have a 23C, but i do have a 45MXT. A 135 lens is for 4x5. I'm doubtful whether you can use a lens that long on a 23C.

 

[DaveFred]

Ah, that would make much more sense.
My memories of using that long of a lens for MF 6x7 stuff was on a 45mxt.
That would make sense why it would have worked for MF there but not in a 23c.
I couldn't find anything in the manual about adjusting travel so this also would explain that.

Maybe the extra travel I am seeing when used with diffusion heads is part of how people were modifying 23cs for 4x5.
For now I am most likely not going to try to adjust. I can just get a lens that makes more sense.

Thank you both.

 

[randyB]

You will need a "top hat" lens board, one that extends the lens at least 1 1/2 inches. The 135mm lens is not normally used with the 23c series. I have a spare 135mm lens and thought I would see how big I could enlarge 6x9 negs on the 23c. I wound up making a "top hat" board. It looks like close to 11x14 is the largest I can go on my 23c. I also wanted to actually see if there was any difference in an enlargement between my 105mm Componon and my 135mm Rogonar S, so far, I see no difference. 105mm is the correct fl for 6x9 negs.

 

[Ian C]

The correct lens for 6 x 7 cm enlarging (as cited in post #1) is 90 mm. There are a few 80 mm lenses that project a sufficiently wide view to project a 6 x 7 cm negative. The 80 mm f/5.6 EL Nikkor and 80 mm f/4 Rodagon are both rated by their makers for up to 6 x 7 cm enlarging.

There are also a couple of 60 mm wide-angle lenses intended for the 6 x 7 cm negative. One of these is the 4/60 Rodagon WA. The shorter the focal length, the greater the magnification for a given negative-to-image distance.

 

[Rick A]

The 23C series enlargers are not designed for that much bellows travel, the largest format they can project is 6x9 cm, so the bellows travel is only long enough to focus a 105mm lens.

 

[Doremus Scudder]

The 23C was designed for negatives 2x3 inches max (2 1/4 x 3 1/4 actually, or 6x9cm), hence the "23" in the name. The usual focal length enlarging lens for that size negative is 105mm. I would imagine that the designers wanted to keep the enlarger size as compact as possible and only designed to accommodate that length. The top-hat lens board solution would work if you need to use a 135mm lens. Keep in mind that you won't be able to get as much enlargement with the longer lens.

Best,

Doremus

 

[DaveFred]

Thanks everyone for feedback. I managed to trade a 50mm omegaron for a 90mm so I should be good. Glad I posted here to get the obvious forest for the trees answer before I totally threw off alignment on a goose chase.