Beseler 23c II Dual Dichro S - Prints coming out reverse vignetted / Dark in center

ac123

Member
Joined
Jun 29, 2023
Messages
57
Location
USA
Format
35mm
I recently acquired a Beseler 23c II with a dual dichro head. I've just started printing on it, but am running across the issue on all my prints where the center circle of the print has an extremely dark exposure compared to the outer edges' exposure.

I've tested this across a couple different lenses, as well as trying a few of the side control settings noted for the negative size, yet the vignette remains. It's noticeable enough that I can see it on the projection in the darkroom (the center being much brighter), but when I remove the lens and look upwards in to the negative/light, it seems like it's fully open with nothing blocking it.

The prints are also coming out fairly purple / red - the top exposure is at 60y 60m 0c, the bottom exposure 30y 30m 0c.

Wondering if anyone has encountered a similar issue on this machine or if I'm missing something? Thanks in advance.

 

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format
It sounds like the head is not fitted correctly -- too high or low -- or something is missing -- diffuser, etc. etc. Maybe that's why the previous owner sold it.

Do you have a manual for the 23C and the colorhead? I'd make sure both are set up correctly -- before anything else -- and then that they are adjusted for the format and lens you are using.

If you've done all that, then wait -- others will jump in with their guesses -- Try this, Try that, Do this, Do that, Here's what I did, Here's what I'd do -- "grain of salt"
 

Rick A

Subscriber
Joined
Mar 31, 2009
Messages
9,942
Location
Laurel Highlands
Format
8x10 Format
Make sure the condenser is set to 6x9. Do not adjust for 35mm or 6x6, those settings is for the regular light source(incandescent).
 

ic-racer

Member
Joined
Feb 25, 2007
Messages
16,552
Location
USA
Format
Multi Format
Check the mixing "box." Are all the pieces there (conic integrator, etc)? Any missing diffusion material or baffles? All installed correctly?

In terms of the filters, have you verified they move to their limits and don't stick open or closed?


 
OP
OP

ac123

Member
Joined
Jun 29, 2023
Messages
57
Location
USA
Format
35mm
I went ahead with checking if there was a diffuser (there was), via the manual's instructions to lift off the color head, detach the top bellows, and look inside the filter area.

Upon reassembly, for some reason I cannot now get the light to come on. ?

The filtration level works (you can see on the front of the machine the indicator switches from "white light" to "diff"). The fan works, and when connected to my gralab timer, I can hear the clicks of the machine that should be turning on the light when it goes on/off.

It's strange because the light was working fine yesterday before I disassembled it, now nothing. I took out the bulb and put it back and it doesn't look broken.

Though I suppose going ahead and ordering a new lightbulb would be the logical thing to try next?




ic-racer said:
Check the mixing "box." Are all the pieces there (conic integrator, etc)? Any missing diffusion material or baffles? All installed correctly?
Click to expand...


The conic integrator, as I understand it, would only be put in if the enlarger is in the "condenser" mode (with the diffuser installed, it auto sets to diffusion)

 

ic-racer

Member
Joined
Feb 25, 2007
Messages
16,552
Location
USA
Format
Multi Format
Yes, which mode are using? Maybe some pictures of your setup would help.
 

mshchem

Subscriber
Joined
Nov 26, 2007
Messages
14,707
Location
Iowa City, Iowa USA
Format
Medium Format
If you are using white light and you switch off, lamp will not light until you switch back to normal, having filters in the light path. This is a paper saver circuit designed to prevent accidentally exposing color paper without filters.
 
OP
OP

ac123

Member
Joined
Jun 29, 2023
Messages
57
Location
USA
Format
35mm
It is set up as no white light / in diffusion mode (as indicated by the lit box)

When I just went ahead and tested the white light lever, I noticed that it did not light up the white light symbol even though it was pushed back to white light, and I did hear the clicks indicating something internal had changed. Before this - earlier today and yesterday - when I pushed back to White Light, the symbol also lit up White Light. Not sure what has changed.

Is there a way to see physically if the white light / diffusion filters are changing properly when the lever is pushed?








ic-racer said:
Yes, which mode are using? Maybe some pictures of your setup would help.
Click to expand...

I'm in diffusion mode. (Pictured without color head)



 

ic-racer

Member
Joined
Feb 25, 2007
Messages
16,552
Location
USA
Format
Multi Format
In terms of the filters, you confirm they move in and out of the path ok without sticking:

 
OP
OP

ac123

Member
Joined
Jun 29, 2023
Messages
57
Location
USA
Format
35mm
ic-racer said:
In terms of the filters, you confirm they move in and out of the path ok without sticking:

Click to expand...

Got it, thank you.

As of right now I'm getting no light at all turning on from the color head when plug into the timer and turn on.

The light was working up until I disassembled and reassembled.
 
OP
OP

ac123

Member
Joined
Jun 29, 2023
Messages
57
Location
USA
Format
35mm
I ordered a replacement bulb and that seemed to fix the light turning on issue.

However I'm still stumped to figure out what's causing the intense hot spot/reverse vignetting in the center of the enlarger light - seen here with and without the lens board on:



When I adjust the right side lever to switch film size formats, the hot spot remains.

I'm in diffusion mode and using it at the 6x9 film size setting as instructed.

Regardless of the lens aperture (2.8 vs 22) the vignette remains in the prints. It remains with multiple lenses at several different enlarger heights.

Essentially every print I make has this intense hot spot where the center is 2-3 stops darker than the edges. It doesn't seem as much of an uneven illumination issue as much as it is a direct center hot spot. I'm using a diffuser / in diffusion mode. I assume that the light should be appearing pretty even in the above images of the direct light projection?
 
Last edited:

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format
I'm assuming that you focused a negative on the baseboard (and then removed it) before checking for the "hot spot".

If so, something is missing or out of alignment/register. Others will jump in.
 

Doremus Scudder

Member
Joined
Sep 10, 2002
Messages
3,596
Location
Eugene, Oregon
Format
4x5 Format
Stop down a couple of stops from wide open and see if the hot spot goes away.

If not, you need to look at your condenser configuration and position if you're using condensers or your diffusion panel and diffuse light-source positions if you use those.

Make sure your enlarging lens is the right focal length and has enough coverage for the format you are enlarging as well.

There aren't that many more variables that I can think of.

Doremus
 

koraks

Moderator
Moderator
Joined
Nov 29, 2018
Messages
23,108
Location
Europe
Format
Multi Format
Sorry, I'm not familiar with this enlarger, but what I see is a massive problem with a diffusor. Doesn't look like a lens aperture problem etc. to me.

I'm wondering about this here:

Is that rectangular insert supposed to be inside the diffusion chamber? It almost looks like a sort of chute that would channel the light from the bulb directly to the opal glass underneath. If so, this would indeed create a very pronounced hot spot.

Maybe someone with the same enlarger can confirm whether that part is supposed to be installed inside the chamber, and if so, that it's complete as shown in OP's photo above.
 

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format
Doremus Scudder said:
Stop down a couple of stops from wide open and see if the hot spot goes away.
Click to expand...

He already said he did -- "Regardless of the lens aperture (2.8 vs 22) the vignette remains in the prints.

I'm in diffusion mode and using it at the 6x9 film size setting as instructed."

And I assume he's not using a 50mm lens!
 

choiliefan

Member
Joined
Dec 27, 2013
Messages
1,314
Format
Medium Format

Wondering the same thing.
One post mentions that it should be a cone.
 

koraks

Moderator
Moderator
Joined
Nov 29, 2018
Messages
23,108
Location
Europe
Format
Multi Format
choiliefan said:
One post mentions that it should be a cone.
Click to expand...

I think that's specifically intended for the condenser setup. I would expect that in the diffusor setup, the bulb shines into a mostly empty chamber with white walls and an exit aperture with an opal glass diffusor. There may be a baffle arrangement to block direct light from the bulb hitting the diffusor, but I have the impression that this is not the case with this particular enlarger. I wonder if the insert was an aftermarket/DIY addition to get faster printing speeds with 35mm negatives at the expense of coverage.
 
OP
OP

ac123

Member
Joined
Jun 29, 2023
Messages
57
Location
USA
Format
35mm

Thank you endlessly! I have no idea what this is but I was able to take the color head off and lift it right out of the diffusion chamber. The simplest solution for weeks of headache. Hot spot is gone now and everything running smoothly.

I think you're on to something about it being an accessory for 35mm negatives, since with it installed I was able to print 35mm negs no issue, it was just affecting 6x6/6x7.

 

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format
I bet that's it. For their 4x5 enlargers, Beseler made two light intensifying mixing chambers (for 6x7 and 35mm formats) for their diffusion color heads -- to decrease exposure times for smaller formats. They replace the standard mixing chamber and have smaller light output ports. They don't look exactly like what's pictured -- they are round and larger, of course -- but they do the same thing. If either were used with larger film formats the light fall-off would be SEVERE!!!!!
 

btaylor

Subscriber
Joined
Dec 28, 2010
Messages
2,256
Location
Los Angeles
Format
Large Format
That object is a light intensifier for 35mm negatives. Now that I see it out of the head I recognize it. I believe it’s only for use with the color head. I have mine in a box somewhere, I don’t think I ever used it. Glad you got that figured out- it would make a heck of an obstruction in the middle of the light path!
 

thepond

Member
Joined
Apr 17, 2024
Messages
6
Location
USA
Format
Multi Format

That part is NOT meant to be used with the 23c II enlarger and Dual Dichro S dichroic color head.

The color head is a direct replacement for the factory bulb holder. NOTHING is supposed to be inside the enlarger body other then the diffusion or condensor lenses.

The bottom outlet for the dichro s color head when in DIFFUSION mode is a plastic piece that looks like a waffle. The white cone/funnel is for when the machine is in condensor mode.

Because the Dichro S head is not built on the same output lines as the factory light bulb version, the height scale is not exactly "spot on" for most negative sizes.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…