Diffusion for Condenser Enlarger

[Timberwolf]

What would happen to black and white prints if I installed some kind of diffusion material under the condensers in a condenser enlarger? I have the circular plastic sheet from an old cold light head that I could drop into the enlarger to place it just above the negative stage. Then I could crank the condensers down the 4x5 negative set. Condensers stay installed. Never mind light loss. How close would this approximate a cold light head, if at all?

 

[ic-racer]

Should make using a glass negative carrier easier (dust will be less prominent). Tradeoff will be longer exposure times.
Since most condenser enlargers are partial diffusion (except point source) the amount of extra B&W negative development needed to match the printing contrast without the diffusion material could be small.

 

[Patrick Robert James]

I've done it myself. You'll get a longer exposure, a little less contrast but also more even illumination.

 

[Paul Howell]

I have a Meopta enlarger that came with similar disk, I've tired it, lowers contrast a bit, increases time quite a bit, another 7 or 8 seconds. In my experience it is not a true diffusion enlarger, not close to a cold head.

 

[BCM]

What would happen to black and white prints if I installed some kind of diffusion material under the condensers in a condenser enlarger? I have the circular plastic sheet from an old cold light head that I could drop into the enlarger to place it just above the negative stage. Then I could crank the condensers down the 4x5 negative set. Condensers stay installed. Never mind light loss. How close would this approximate a cold light head, if at all?

I took some glass and had it sandblasted years ago to hope to reduce dust on some enlargers we had at a school. We had to move the condensers up because we got a hot spot. The next step was to take a condenser and have it sand blasted. That actually helped a bit but none of it ever worked as well as a cold light head.

 

[Hilo]

For their Focomat Ic Leitz made this diffusing glass. Later on I am at work and will have a look, it's been a while that I have seen it. Perhaps it came with a special condenser.

I never used it. But I suspect it will do what's in the posts of the others here. Except for only a couple of negatives, I have never wanted to use anything else but the condenser heads of my enlargers (Focomats Ic and IIc, Valoy II and the Durst L1000).
The few 135mm negatives that needed very even illumination with less contrast, I just printed these with the IIc.

 

[markbau]

It should be pointed out that for normal enlarging there are only two types of illumination, condenser and diffusion. (Point source is a seperate subject) "Cold Light" is not a separate type of illumination, it is just diffusion illumination performed with a tube instead of a mixing box.
Putting some sort of diffusing material in-between the condensers and the neg stage will turn your enlarger into a diffusion enlarger of sorts.

 

[Paul Howell]

It will, not as well as a designed diffusion enlarger, cold head or color head, or older style with a mixing box of some sort.

 

[Paul Howell]

I just checked out the prices for Federal enlargers, I paid $15 for mine + shipping was around $20, that was 10 to 11 years ago. Today most are ranging from $75 to a $100 + shipping from $65 to $80. Prices are way too much for a low end enlarger, I would look for a color or cold head. If you have an Omega D2 or 3 you can also look for the circular florescent cold head, with luck will have the electric shutter. With a florescent head you need to use graded paper our use a CCY20 filter with VC paper.

 

[snusmumriken]

Like @patrickrobertjames, I've tried this. You need longer exposure times, also to print at a higher contrast grade. I didn't see any difference in evenness of the light, but that may be related to the enlarger design. The image detail will be slightly less crisp.

In case you were hoping to overcome the Callier effect and achieve tonality like in your contact prints - as I was - it doesn't work!

 

[NB23]

For their Focomat Ic Leitz made this diffusing glass. Later on I am at work and will have a look, it's been a while that I have seen it. Perhaps it came with a special condenser.

I never used it. But I suspect it will do what's in the posts of the others here. Except for only a couple of negatives, I have never wanted to use anything else but the condenser heads of my enlargers (Focomats Ic and IIc, Valoy II and the Durst L1000).
The few 135mm negatives that needed very even illumination with less contrast, I just printed these with the IIc.

Why the IIc? It’s a condenser enlarger...

 

[Timberwolf]

Like @patrickrobertjames, I've tried this. You need longer exposure times, also to print at a higher contrast grade. I didn't see any difference in evenness of the light, but that may be related to the enlarger design. The image detail will be slightly less crisp.

In case you were hoping to overcome the Callier effect and achieve tonality like in your contact prints - as I was - it doesn't work!

Thank you snusmumriken. I am interested in tonality to match contact prints or a true cold light head. I believe you that it doesn't work, but I wonder why not.

 

[snusmumriken]

I think it’s because in the contact print the negative is adjacent to the paper; whereas in the enlarger any light that is not axial (ie scattered by your diffuser) will be lost sideways in the space between negative and paper.

 

[Paul Howell]

I think for a true diffusion enlarger you need to mix the light so that there is no callier effect at all, with a set of condensers the light is focused, the callier effect, a frosted or milk glass insert does not totally correct the callier effect. My Federal enlarger, uses a large clear blub, the interior of the enlarger head is painted white, (I added the white paint, paint designed for high heat) along with the white milk glass light is reflected and mixed. A point source enlarger is the total opposite, it uses a double condenser, a small clear blub, the interior is painted flat black, the light source can be moved up and down to keep the light in total callier effect. The enlarger lens is kept wide open and a transformer with variable output to control the intensity of the light.

 

[Paul Howell]

Looking at my D3 with VC head, maybe if you took out the double condensers, had a glass shop cut a milk glass plates to fit the bottom and top racks, then used a LED bulb, maybe a 3200 lumens. The two white glass plates might make a mixing chamber of sorts, you will need a LED bulb so as not to overheat the top glass.

 

[Hilo]

Why the IIc? It’s a condenser enlarger...

for 135mm, between the Focomats Ic and IIc, the latter gives a more even illuminated print. This is mostly because of the large condenser with double glass lenzes: the small 135mm negative only uses a small part of the projected light. You only notice the difference with a light and even image.

 

[NB23]

for 135mm, between the Focomats Ic and IIc, the latter gives a more even illuminated print. This is mostly because of the large condenser with double glass lenzes: the small 135mm negative only uses a small part of the projected light. You only notice the difference with a light and even image.

I’ve had problems with my IIc’s illumination, had to play with the bulb to get it right. My Ic was always perfect.

Damn I Love those enlargers

 

[Hilo]

Yes, compared to some other enlargers the Focomats (also the Valoy II) are slightly erratic as far as even illumination is concerned. Sometimes it helps to use the shortneck bulbs (less long).

Of course this also depends on your images and on our personal taste where it concerns more or less contrast. Daido Moriyama, or Eugene Smith, or Dave Heath: photographers who love(d) a lot of contrast. Moriyama with his early work hardly cared about anything, except to reach a kind of an emotional printing. He would not have worried about even illumination. Smith, and Heath in particular were very fine printers who reached a beautiful darkness in their prints.

 

[Doremus Scudder]

Well, if you have an uneven illumination problem, you'll need to fix that.

If you think you can get the same "tonality" from an enlargement as from a contact print by using a diffuse light source, you are mistaken. That's not to say that enlargements aren't good, it's just that even with a completely diffuse light source (I use cold light heads and color heads with mixing chambers), the contrast of a contact print will be different than the contrast of an enlargement made on exactly the same paper with exactly the same filtration. Enlarging systems introduce flare. This can be minimized, but not eliminated. With a diffuse light source, you'll almost always need a higher print contrast to match the contrast on a contact print.

My advice: unless you plan on making contact prints for exhibition, concentrate on finding the sweet spot in film exposure and negative development time that allows you to make excellent prints from "normal" negatives on an intermediate contrast grade. Then, work on refining your printing technique.

Best,

Doremus

 

[ic-racer]

If your 1:1 projection prints don’t look like your contacts then something might be wrong.
Maybe post some examples.

 

[RalphLambrecht]

What would happen to black and white prints if I installed some kind of diffusion material under the condensers in a condenser enlarger? I have the circular plastic sheet from an old cold light head that I could drop into the enlarger to place it just above the negative stage. Then I could crank the condensers down the 4x5 negative set. Condensers stay installed. Never mind light loss. How close would this approximate a cold light head, if at all?

You will most likely lose a lot of light and end up with extended exposure times. You'll be better off developing the negatives to match your enlarger's contrast needs.