I am using an old Beseler 45 Dichro Color Computer head for my B&W printing and have been using filtration settings based on recommendations that came with some Ilford paper. These settings are a wild swing from the recommendation that came with the head,which is at least 5 years old, but I am happier with the amount of change I get between grades and the new settings allow me to get very nice results using the contrast/grade calculator built into the head. My question is how do I determine what grade I am actually getting? Is there a test negative or some other method that allows me to make a test print that I could then use to calibrate my head? The reason I ask is twofold, first I just tried my first batch of Kodak RC paper and the grades appear to be different from the FB work I have done up to this point. The second point is I would like to print some of my better prints on graded paper and want to make sure that what I print as a #2 filter pack will look close to the same on a #2 graded paper.

Thanks in advance,

-- Harry Pluta (hspluta@msn.com), February 22, 2000

Answers

You need a step wedge negative (buy one, or make your own with a transmission densitometer). Make prints of this, and use a reflection densitometer to measure the results. A bit of simple maths gives you the paper grades.

Or you might just empirically test the paper. Make some straight prints on graded paper, then make some on the new paper, and adjust until they match the old ones. Keep careful notes, and you will then know how to convert between the two systems.

-- Alan Gibson (Alan@snibgo.com), February 22, 2000.

Step wedges are available form Stoufer Graphic Arts, Kodak, The View Camera Store and others. Print the step wedge using different filter settings, develop the paper then count the steps between white and black. Low contrast paper will yield more grey steps, high contrast less. Steve Anchell's Variable Contrast Printing Manual has a wealth of info on this and other topics.

Regards,

-- Pete Caluori (pcaluori@hotmail.com), February 22, 2000.

Actually, you can't be sure that grade X on paper A will look the same as grade X on paper B, for (at least to my knowledge) the grade designation is not standardised. So to get an empirical grade designation, you should get a (transmission) gray step wedge that you can contact print on samples of the papers in question. Gray step wedges have a number of gray steps in specified increments of log D. The smaller the increments the finer you will be able to determine the grade of your paper, hence the more certain you can be of consistency when going from one paper to another.

I know of at least one gray step wedge from Kodak, which has 0.15 log D steps up to 3 (I think). I think it costs about 100 USD. Maybe there are generic brands that are cheaper. If you onw a transmission densitometer (or a lab exposure meter and a pocket calculator), you can make your own step wedge.

Now, assuming you have got a suitable step wedge:

To determine the contrast range of a sample of paper, find the exposure where the first (clear) step of the wedge is definitely the blackest black that the paper can produce. In a dry contact print of the wedge made using this exposure, count the discernible steps before paper base white. This number multiplied by the density increment of the step wedge gives you the contrast range of the paper.

In fact, the designation of the contrast range in terms of log D is standardised: The log D range determined as above, multiplied by 100 and with an R before it, gives you the standardised contrast designation. To my knowledge, however, R 150 might be grade X paper of brand A whereas brand B has R 130 at the same grade.

Still, using the method above, you will be able to determine the contrast ranges of your VC and graded papers, and you will know the difference.

-- Thomas Wollstein (thomas_wollstein@web.de), February 23, 2000.

Thanks to all for the responses!

I appreciate the fact that each paper might be different, but it sounds like a step wedge and a bit of testing will allow me to calibrate my system for each paper that I want to use. I am used to doing this level of testing for color filtration with Cibachrome paper on a batch to batch basis, so it was just a matter of finding and understanding the right tool for B&W.

Thomas, many thanks for taking the time to explain the mechanics, I recently reread The Negative and feel like after almost 30 years I am starting to understand the WHY of this stuff instead of just the HOW.

Best Regards, -harry

-- Harry Pluta (hspluta@msn.com), February 23, 2000.

Although not a direct answer to your question, let me offer some food for thought.

Since getting a Zone VI VC head for my Besseler, I have changed my approach to the way I gauge "grades". I believe with your dichro head, the same process could be used.

I start with a test strip made with only the softest light. After processing and determining the section that gives me the high value I desire, I make an exposure for this time. Without removing the new strip, I make a test strip using only the hardest light. After processing the strip with the soft base and the hard test, I can determine the section that gives me the low value I desire.

The resultant print doesn't have an actual "grade", but I have found that my prints made in this fashion all match very closely in "contrast", which happens to be what I desire. I look for a continuity in my prints, the overall "look", although of very different subjects, is important to me.

Like I said,just some food for thought on a little different take on your question.

-- Marv (mthompsonn@home.com), February 24, 2000.