View Full Version : Variable contrast printing question

brian steinberger
8-Oct-2005, 23:11
I have a Beseler Dichro 45s. When printing with more contrast, do I need to increase exposure? And vise-versa with printing with lower contrast. And also, are there any good books on printing with variable contrast papers? Thanks

Craig Wactor
8-Oct-2005, 23:32
when using ilford filters, prints with the same exposure have consistent highlight value for filters #1 - 3 1/2. The shadows change, getting darker with a higher filter. Filters #00- 1/2 and 4-5 need double the light. The little info pack in your paper box will tell you a good bit of info.

Larry Gebhardt
9-Oct-2005, 04:43
If you are using the built in yellow/magenta filters you will need to refigure the exposure when you change the contrast.

If you use under the lens filters you might not depending on how you print. The Ilford filters are made to keep the exposure times the same (as mentioned above) for a certain midtone value. So both your highlights and shadows change when you change filters. Since I judge exposure from the highlights I need to refigure the exposure when I change filters.

9-Oct-2005, 04:44
depends on your enlarger, filters and paper.

knowing how to calibrate your dichroic filtration so as to give evenly spaced grading with consistent times for each grade is not a trivial task. Besides, unless you want to reduce the print making process to a "print by numbers" process then exact calibration is not necessarily a must.

My durst L1200 with CLS 501 head is extremely well calibrated to Ilford MGIV paper using Ilfords Y+M figures for my enlarger. However, the speed matched print density is a logD of just under .7 which is a mid tone and not a highlight tone. Also the quoted grade 2 settings are not an ISO grade 2. The quoted grade 3 settings are very close to an ISO grade 2.

I now calibrate my film development for the Ilford Y+M Grade 2 figures for my enlarger. I mention this because it means I need more film development to print normally than I would if I calibrated to an ISO grade 2 contrast setting. This means that I get better film speed than might otherwise be the case.

What is most important for you is that you know which print density is the speed matched density across grades and if infact your enlarger is speed matched for the Y+M figures for your paper. Often this is not the case and it is certainly not a truism that the speed match density will be a highlight density. However, as has already been said, Ilford MG filters do speed match in the highlights.

Two books which come to mind are Steve Anchells Variable Contrast Printing manual and another book which I have not read, called Way beyond Monchrome by Ralph Lambrecht and Christopher Woodhouse. Both books go into great detail about calibrating filtration for VC papers. I expect there are many others.

ronald moravec
9-Oct-2005, 04:44
With Ilford paper and filters, I have to add 10% time when moving from 2 to 3 amd the same for 3 to 4 in addition to the time increase for 4&5 filters.

I print to keep the highlight the same density and let the contrast control the shadows. I usually use a condenser enlarger for black and white.

The filters are designed to maintain the same exposure for mid grey. Therefore a higher contrast print lack s density in the highlights.

All bets are off if you use any cold light head. You get weird responses even with the Aristo V54.

Paul Butzi
9-Oct-2005, 10:01
Several points:

1) do Ilford filters speed match for the highlights? Yes and no. Ilford filters, if I recall correctly, speed match for a fairly light tone. However, there are several Ilford papers, and they do not respond to the filters the same. Speed matching may be very good for Ilford MG IV fb, for instance, but it will not be the same for Ilford MG IV rc, nor for Ilford MGIV rc coldtone, nor for the Ilford warmtone VC papers, both RC and FB.

2) Ilford filters will not be speed matched for any paper except the one ilford paper they work well for. You might get approximate speed matching, but not exact. For many papers, such as the Forte papers, the speed matching will be so bad as to be worthless.

3) Ilford publishes m+y filtration values which are purported to be speed matched. In my experience, they are only vaguely speed matched, and if the speed matching is not exact, why bother? Once you're forced to do the work to find the new exposure, it matters little if the adjustment was small or large.

4) It's possible to produce a chart of time corrections - this was described long ago in an article by Howard Bond in Photo Techniques, and then again in another article more recently. Some folks prefer to adjust time rather than speed match filtration, primarily because it allows for shorter exposure times.

5) You can easily calibrate your enlarger filtration using any of several methods. One method (the one I prefer, naturally) is described in an article on my website at www.butzi.net/articles/vcce.htm (http://www.butzi.net/articles/vcce.htm). It's an updated version of the article that was published in Photo Techniques years back. Another technique is outlined by Ralph Lambrecht in 'Way Beyond Monochrome'.

6. Some folks recommend Steve Anchell's book on variable contrast printing. When I bought a copy I found so many fundamental errors (such as the claim that cyan filtration can be used as neutral density) that it was completely worthless. If it was the only book on VC printing, that would be one thing, but there are others which are quite good ("Way Beyond Monochrome" is one, Ephrams book is another).

Arthur Nichols
9-Oct-2005, 15:47
The Dichro 45 S should give you good contrast control by changing the ratio of yellow to magneta light. You do not need any filters. Here is the link to a document by Ilford that gives you settings for your color head to provide different contrast levels. I have used this table for years with my Beseler Dichro 45 s and it works well.
Here is the link: http://www.ilford.com/html/us_english/pdf/Cont.pdf
This is all you need to know about using your color head with VC papers. Of course additional information is helpful and any of the above named books are good. Start with the Ilford document and work with it for awhile, then see what else you want to learn.