Bessler 23C II Condenser "Warm Up" Issue

DMCCAFF · May 16, 2020

I have an issue where my enlarger has to warm up for a few seconds to be in focus. This make no sense to me... even if the bulb needed to warm up, how would that affect the focus?

I have an Eiko PH140 bulb in there and have the same issue when I bypass the timer. I was also thinking it could just be my eye readjusting... but it's not.

It takes 2 to 3 seconds for the grain to come in focus after a few minutes of not being used. I'm printing a lot of 8x10s from 35mm negs and with my lens stopped all the way down my full exposure time can be as quick as 1.6 seconds. I've taken to covering up the whole sheet of paper and running the lamp a few seconds before each print and test strip... but that seems absurd.

I can't seem to come up with anything trying to google this problem... anyone with condenser experience run into something similar?

logan2z · May 16, 2020

My guess is that you are experiencing 'negative popping'. I had the same issue with my 23C when I was using a glassless carrier. The heat from the enlarger bulb causes the negative to deform sufficiently so that it no longer sits flat in the carrier and that causes the focus to shift. As a workaround I also used to 'pre-heat' the negative before starting the timer - I'd use an under-the-lens red filter for a bit of time until the negative popped and then I'd remove the filter and start the exposure. It works but it's a pain. A glass carrier solved the problem for me.

Pieter12 · May 16, 2020

It is your negative warming up...two things I would advise: if there is a filter slot or drawer above the negative stage, a heat-absorbing glass and maybe and ND filter to lengthen your exposure times. You don't want to use the lens all the way stopped down, you will have diffraction and the prints will never be sharp.

logan2z · May 16, 2020

Pieter12 said:
It is your negative warming up...two things I would advise: if there is a filter slot or drawer above the negative stage, a heat-absorbing glass and maybe and ND filter to lengthen your exposure times. You don't want to use the lens all the way stopped down, you will have diffraction and the prints will never be sharp.

Good advice, although I found that, even with the heat absorbing glass in place, I still experienced negative popping.

ND filters are a good way to increase exposure times. I use these for this purpose (when needed):

https://www.bhphotovideo.com/c/prod...2124_E_Colour_210_6_Neutral.html?sts=pi&pim=Y

They work great, are cheap, and can be easily cut to fit into the filter drawer above the lens of the 23C II.

DMCCAFF · May 16, 2020

Wow, thanks for the quick replies. I actually think I heard a pop earlier so you are probably right.
My Rodagon 2.8 50mm lens only closes down to f8 for some reason, tho it lists an f11. I though 5.6 to 8 would be a safe range... would you rec going to 5.6 over 8 for diffraction?

Pieter12 · May 16, 2020

DMCCAFF said:
Wow, thanks for the quick replies. I actually think I heard a pop earlier so you are probably right.
My Rodagon 2.8 50mm lens only closes down to f8 for some reason, tho it lists an f11. I though 5.6 to 8 would be a safe range... would you rec going to 5.6 over 8 for diffraction?

It seems odd that it doesn't stop down. I would think it should even go to 16. Is the preset engaged? Some enlarging lenses have a feature that allows you to preset the f-stop, so you can focus wide-open and then stop down easily in the dark to your preset.

MattKing · May 16, 2020

Welcome to Photrio.
Your lens aperture probably has the lock engaged. That lock is designed to allow you to set the aperture to a particular opening - f/8 in your case. You can then easily rotate the ring all the way in one direction for fully open to permit easier focusing, and then all the way in the other direction to return it exactly to the set position.
Try pulling down on the ring to release the lock and permit setting the aperture to a smaller opening.
Don't be overly concerned about diffraction. It tends to only create visible problems in prints when the prints involve high degrees of enlargement. When the enlargements are big, short exposure times are never a problem. For small prints, f/16 probably won't make a noticeable difference.

Dan0001 · May 16, 2020

If you are doing mostly 8 X 10's or smaller, the exposure times seem awfully short. I had a similar problem with my Omega B22 and instead of heat absorbing glass I used a light dimmer(rheostat) and have reduced the light output about 50%. It probably extended my light bulb's life considerably as well. I have not noticed any light fluctuations either. Having extended exposure times allows greater flexibility using variable contrast filters and with burning and dodging. For larger prints I can always boost the rheostat.

Pieter12 · May 16, 2020

It may not be an issue, but it seems to me that a dimer also affects the color temperature of the light. Which could affect the use of VC filters.

Dan0001 · May 16, 2020

I personally have not noticed any problems with variable contrast filters( which I use below the lens). If there is any color temperature change I think it is negligible especially for B & W printing. In my Michigan home I have a 4 X 5 Beseler with Zone VI cold light...it has variable light intensity ability also but it is a little more sophisticated than the simple light dimmer on the B22.

Vaughn · May 16, 2020

DMCCAFF said:
I...I've taken to covering up the whole sheet of paper and running the lamp a few seconds before each print and test strip... but that seems absurd...

Did this for years (not for test strips, tho) -- 4x5 on an Omege D5-XL. Just became part of my routine. A glass neg carrier is another solution...at the price of having 4 extra surfaces to get dust on.

Pieter12 · May 16, 2020

Out of habit (and despite using a very efficient pice of heat-absorbing glass in the filter drawer), I will usually turn on the enlarger lamp to warm the negative for a minute or so and then turn it off before inserting the paper and making the actual exposure. I dislike glass carriers, really having a hard time simultaneously keeping 6 surfaces free of dust. This way, my prints require a minimum of spotting--another think I don't really relish doing.

Pieter12 · May 16, 2020

Obviously, I focus when the negative is warm.

mnemosyne · May 21, 2020

Not familiar with the Beseler, but if the condensor system uses a normal screw in tungsten opal lamp as light source you might consider to replace it with a suitable LED bulb. There are some threads here on Photrio that cover this. The LED bulb will solve any heat problems once and for all. On top, you get an extremely bright and easy to focus picture on the easel/baseboard. The downside is, depending on the specs of your bulb, your exposure times might become even shorter. But this can be addressed with ND filters or a frosted light scattering filter. Too much light is always better than too little. And be prepared that variable contrast grades might shift a bift from what you were used with the tungsten lamp. Good luck!

Bessler 23C II Condenser "Warm Up" Issue

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