Graded papers and light sources.

[Rolleiflexible]

Please forgive what must seem an unbearably stupid question:

The common wisdom is that, when enlarging, cold-light sources give softer results than condenser light sources, so that a negative that needs a #2 filter when printed with a condenser head onto VC paper will need a #3 filter with a cold-light diffusion head.

Does this apply also to graded papers? I have negatives that I print with a cold light head that need a Grade 4 paper. If I print them with a condenser light source, can I get by with a Grade 3 paper? I'm assuming it doesn't work that way, but please, someone give it to me straight.

Sanders.

 

[Simon.Weber]

I think - but I do not know - that it has nothing to do at all with the light colour but with the directionality of the light ... a condenser head is somehow "less fuzzy" than a diffusor.

But don't call me on it; I may be wrong.

 

[Michel Hardy-Vallée]

The basic principle of condenser-more / diffuser-less in terms of contrast apply regardless of the type of paper used. It's just a feature of the lightrays shining through the negative, not a question of light temperature.

As for how much you need to change grade, I wouldn't go as far as a full grade. I've done my own side-by-side comparisons between cold light and condenser on grade #2 paper, and decided that the difference was not large enough for me to bother. YMMV, but make some tests using your usual paper, changing only the light source. That way you're controlling a single variable. You will be able to decide whether you need to adjust the final contrast.

 

[janjohansson]

Basicly your logic is correct, however, the exact grade of the filters with
the diffrent lightsources could be less or more than the difference implied
by the filters.
The change in contrast also depends on the paper used. Some papers
respond not linearly with the filters, ie the change in contrast could be
more or less than one grade.

You could/should make some tests of the paper(s) you use, printing
stepwedges (projected) and from them judging the obtained contrast grade for
the diffrent filters/lightsources/papers.

If i recall it corectly Anchell elaborates on this subject in his "The variable contrast
printing manual".

An alternative to use softer grade with the condensor-head is to use a soft
working developer while using same graded paper.

 

[David A. Goldfarb]

Another way around this is to target your negative development time to the light source, if you know you'll be printing consistently with the same enlarger.

 

[j-fr]

A subtle but useful change

It is correct that condensor ligth prints with higher contrast than diffused light. But: The change is in the highlights - it's not an all-over change as when you change from filter #2 to filter #3. So for fine art printing it's a good idea to have both light sources at hand for the enlarger. The difference is subtle, but useful.

j-fr

www.j-fr.dk

 

[Rolleiflexible]

You all are giving me useful information, but (MHV's post excepted) it is not answering my question.

My question: Does a graded paper change contrast depending on the light source? Will an Ilford Grade 3 paper give me higher contrast if I print it with a condenser light source, instead of my cold light diffusion head?

That's the question. I assume the answer is "No." I assume that a graded paper's contrast is governed by the emulsion, and its interaction with the developer, and that the color or directionality of the light is irrelevant. Am I wrong?

Sanders

 

[lee]

Sanders,

I think the contrast will go up using a condenser light source regardless of the paper. Whether graded or VC. Years ago when Graded papers ruled the earth you had to develop the film for the light source not the type of paper.

lee\c

 

[Michel Hardy-Vallée]

My question: Does a graded paper change contrast depending on the light source?

Yes, but not a lot.

 

[Helen B]

I agree with j-fr. The difference appears to be more pronounced in areas of greater density in the negative and less pronounced or insignificant in thin areas.

Best,
Helen

 

[Sal Santamaura]

...My question: Does a graded paper change contrast depending on the light source?...

First, realize that there will be differences between a grade 2 graded paper and a multicontrast paper printed through a grade 2 filter. See the discussion of that subject in the "Ilford Galerie vs. MG IV" thread:

(there was a url link here which no longer exists)

To simplify your question, let's list some assumptions.

• We're comparing a graded paper with a multicontrast paper using a filter that results in a characteristic curve exactly the same as the graded paper. This won't happen in reality.
• You'll print the same negative on both papers using the same pair of light sources, etc.

In this hypothetical, the answer to your question is no. The graded paper does not change contrast; neither does the multicontrast paper. Both prints will, however, be subject to the Callier effect with a condenser source, resulting in elevated high print values. This physical phenomenon is a manifestation of collimated light bouncing around the actual silver clumps in a negative and is related to how closely spaced those clumps are. Since they are densely packed in the negative for high values in a scene, resulting values in the print become disproprtionately higher there. None of this applies to color negatives, where dye clouds rather than silver clumps exist, and no scattering is possible.

The essential concept that may be difficult to get a feel for is that differences in light sources are an optical system characteristic independent of paper type. The only relationship between the two is that one must select graded paper grade or a multicontrast paper filter with appropriate contrast to match the negative and enlarging system. The different light sources don't know or care what paper one uses; they do what they do to project image scale regardless.

 

[George Collier]

To really understand what is going on with cold light vs condensor (or even point source, a rare thing today), you have to read up some on what is called the Callier effect (no relation).
In simple terms, as j-fr and Helen mentioned, highlights are affected the most. The quality of the light coming from a condensor is columnated, or linearized to pass through the emulsion. Scattering occurs when passing through the silver grains, which impedes the light's passage as it exits. This happens more in the highlights than shadows because of the greater density of silver. This increases the contrast in an artificial way, and an enlarged print will have more contrast than a contact from the same neg, since this doesn't happen in contact printing, and I believe it gets worse with greater enlargement.
The Cold Light, on the other hand is already diffused, so this phenomenon doesn't occur as it passes through the emulsion, giving a better rendition of what is in the negative. The argument for using a cold light is that you can expand the contrast in film development, building better separation (and therefore information) into the final neg image.
The first time I used a cold light (Aristo), I made a comparison with my condensor head, and found that I could use a higher contrast paper, giving me better shadow separation and detail, without "chalking" up the highlights. I never went back. Also, since I use 35mm, 2 1/4, and 4x5, I don't need all those condensors, you don't make any changes with a cold light when going from format to format.
Google the term "Callier Effect" and you will find discussions on Photo.net.
Someone chime in if I am off anywhere here.

 

[Matthew Gorringe]

Hi Sanders,
I assume this is related to your question on getting more contrast out of grade3 Galerie?

I wouldn't use a condensor system because the quality of the contrast changes and I happen to like a diffusion light source. In your case it's unlikely that you'll get significantly more contrast but the quality of that contrast will certainly change.

Any chance you could hire a darkroom with a good quality point light source enlarger to try?

 

[Rolleiflexible]

Thanks, all. I appreciate the education. Sanders.

 

[janjohansson]

Evening,
A little while ago there was an informative thread on the difference between diffusor and
condensor in the forum darkroom->enlaring. Or maybe the little and hard to detect
differences. I think it was at most just a few weeks ago it was active.

-J