Beseler 23C II Diffuser Head

camera_allure · Jan 28, 2025

Hello all, I am relatively new to printing and have only recently successfully built out a darkroom in my apartment. I use a Beseler 23C II enlarger with the typical condenser head, and so far so good. I am curious about diffusion, however, and I found a used diffuser for the 23C II for $20 (basically just the opal glass in its housing). My understanding is that this diffuser head was typically provided for the dichroic system, so would there be any compatibility issues if I don't have the dichroic lamphouse? I'm using the standard tungsten bulb setup.

Oh, and a bonus question if you all might be so kind: I have found that significantly raising or lowering the enlarger creates alignment issues. I have the versalab laser alignment tool thankfully, but this strikes me as a real speedbump in terms of workflow. Is that just something I should get used to?

Thanks for any help with this, and happy printing!

Ian C · Jan 28, 2025

Diffusion Unit

The Beseler 23C series diffusion unit uses an upper and a lower sheet of diffuse plastic instead of the 2-lens condenser set. The conventional 75-watt opal lamp, horizontal-burn PH-111 or vertical-burn PH-140, depending on its year of manufacture, doesn’t produce nearly enough light for practical enlarging when the diffusion unit is installed, as it absorbs too much light.

To use the diffusion unit, you need one of the dichroic lamphouses: DGA, Dual Dichro, or Dual Dichro-S installed. You must also install the HEX-CELL DIFFUSER over the light port on the bottom of the dichroic lamp head. The CONIC INTEGRATOR is intended only for use with the condenser unit.

http://www.jollinger.com/photo/cam-coll/manuals/enlargers/beseler/Beseler_DualDichro23_head.pdf

Alignment

The only critical alignment is that between the lens axis and the negative. Changing the projection distance (raising or lowering the head on the column) won’t affect this. But a sensitive tool like the Versalab might show a difference in the baseboard-to-lens-axis alignment upon changing the projection distance. It’s meaninglessly small and won’t alter the resolution or uniformity of the projection. There’s nothing wrong with it. It’s a photo enlarger—not a machine tool or precise instrument in a precision-measurement inspection lab.

Focus Spoiled by Lamp Heat and Resultant Negative Popping

In my experience, one of the biggest problems with the Beseler 23C, or any other modern condenser-type enlarger, is the heat produced by the lamp. It falls most strongly on the top surface of the negative and causes it to temporarily form an upward “belly” that rises out of the shallow depth of field about the negative. This spoils the focus of the projection, so that it is non-uniform—some areas in focus and others fuzzy.

The solution is to install a heat-absorbing glass filter—NOT WINDOW GLASS, to absorb the excess heat before it reaches the negative, and to restrain the negative between the glass plates of a glass negative carrier. You can also make a simple glass carrier out of two sheets of glass. They are easy to make and work well. Photrio member ic-racer posted an article in the past with a photo of such a homebuilt carrier. Perhaps he’ll read this and post the link to that article in this thread.

If you use the “SEARCH” function, you can find many posts relating to the Beseler 23C, 23CII, and 23CIII. Many of your questions, even ones you haven’t thought of yet, have been discussed and practical answers given.

camera_allure · Jan 28, 2025

Ian C said:
Diffusion Unit

The Beseler 23C series diffusion unit uses an upper and a lower sheet of diffuse plastic instead of the 2-lens condenser set. The conventional 75-watt opal lamp, horizontal-burn PH-111 or vertical-burn PH-140, depending on its year of manufacture, doesn’t produce nearly enough light for practical enlarging when the diffusion unit is installed, as it absorbs too much light.

To use the diffusion unit, you need one of the dichroic lamphouses: DGA, Dual Dichro, or Dual Dichro-S installed. You must also install the HEX-CELL DIFFUSER over the light port on the bottom of the dichroic lamp head. The CONIC INTEGRATOR is intended only for use with the condenser unit.

http://www.jollinger.com/photo/cam-coll/manuals/enlargers/beseler/Beseler_DualDichro23_head.pdf

Alignment

The only critical alignment is that between the lens axis and the negative. Changing the projection distance (raising or lowering the head on the column) won’t affect this. But a sensitive tool like the Versalab might show a difference in the baseboard-to-lens-axis alignment upon changing the projection distance. It’s meaninglessly small and won’t alter the resolution or uniformity of the projection. There’s nothing wrong with it. It’s a photo enlarger—not a machine tool or precise instrument in a precision-measurement inspection lab.

Focus Spoiled by Lamp Heat and Resultant Negative Popping

In my experience, one of the biggest problems with the Beseler 23C, or any other modern condenser-type enlarger, is the heat produced by the lamp. It falls most strongly on the top surface of the negative and causes it to temporarily form an upward “belly” that rises out of the shallow depth of field about the negative. This spoils the focus of the projection, so that it is non-uniform—some areas in focus and others fuzzy.

The solution is to install a heat-absorbing glass filter—NOT WINDOW GLASS, to absorb the excess heat before it reaches the negative, and to restrain the negative between the glass plates of a glass negative carrier. You can also make a simple glass carrier out of two sheets of glass. They are easy to make and work well. Photrio member ic-racer posted an article in the past with a photo of such a homebuilt carrier. Perhaps he’ll read this and post the link to that article in this thread.

If you use the “SEARCH” function, you can find many posts relating to the Beseler 23C, 23CII, and 23CIII. Many of your questions, even ones you haven’t thought of yet, have been discussed and practical answers given.

I appreciate your response, thank you. I have already installed heat absorption glass in the slot above the filter tray, and so far I have not experienced any negative popping due to heat. Since my original alignment job with the versalab I haven't observed any drastic changes in focus with my prints, just a noticeable change in the laser placement when using the tool and with the lamphouse at a significantly higher position than before. The only reason I checked at all is out of curiosity and perhaps to avoid wasting more paper than necessary. Glad to hear that I needn't worry about precision quite so much.

A shame about the diffuser, but perhaps I'll try to find a dual dichro head someday once I have nailed down my skills with the condenser head. I would like to experiment with RA-4 someday anyway. All that said, I have gotten lovely results so far with b&w on the condenser, so it's no big deal to continue on this trajectory for a while longer.

Thanks again for the prompt and informative reply, it was most helpful.

Cheers,
Nick V.

Sundowner · Jan 31, 2025

Two thoughts:

Don't throw out the diffuser until you've played around with it. As I'm continually discovering, there are all kinds of ways to do this stuff; check out this thread for some additional info, and for even more proof that I have no idea what I'm doing.
The 23C is a good chassis with a lot of adjustability, and you shouldn't have much shift in parallelism as you go up and down the elevation range. Before you do anything else, check your chassis for squareness; you may find that something is loose, wracked, bound-up or otherwise unhappy. Pull the head and go through the entire chassis, and re-square all of it.

Hit me up with a PM if you want a detailed walkthrough on how to do the re-square; I don't want to clutter your thread with a long instructional post about a non-standard method if you don't need one.

Oh, question: is the enlarger in a permanent spot, or do you need it to remain mobile? If it stays where you have it at current, there are some very good options for fine adjustment.

Paul Howell · Jan 31, 2025

For best diffuser head get a basic color head. You can print without a filter or if you use VC paper you can use the M and Y filters.

Beseler 23C II Diffuser Head

camera_allure

Ian C

camera_allure

Sundowner

Paul Howell

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