Contrast grades on older Durst colorheads (100 max value). Help needed!

[thaung]

Hi, I was wondering if anyone can shed any light on this subject. I use an old Durst M800 usually setup as a condenser but sometimes I want to use it as a diffusion enlarger using a CLS70 head and Sesiboxes.

My problem is that I am trying to find some sort of guide as how to use the filtervalues. On Ilfords data-sheets there are filter-tables for colorheads with max values of 130 and 170 but these old heads only goes up to 100. Does anyone have any old instructions or filtergrade-tables for the old heads? Or for that matter any other ideas. I know I can start experimenting with different setting myself but I´d rather not spend paper if I don´t have to.

Since the filtertables for the other Durst heads (130, 170) is different from one another at the same filtergrades it is probably correct to assume that the higher max values doesn´t necessary mean that those heads is able to reach higher/lower contrast grades, but rather have a scale that is more "streched", correct?

Best regards
Rasmus

 

[GeorgesGiralt]

Hello Rasmus,
You have to calibrate the head for yourself to get good results. (Contact print a Stouffer step wedge with, say 0 M and 10 Y, then 0M and 20Y... up to 100 M 0Y process paper sheets and count the discernible steps. Knowing the step increment, you'll devise the contrast range. Plot it and look at the ISO paper range to get the grade values...
Boring, time consuming and costly.
IMHO, buy a set of under the lens Ilford filters and you're done. This way, you'll get excellent and consistent results either with the condenser or color head, you'll be able to sue more than one grade on the same print without fearing to make the enlarger head move and ruin the print......
The price you paid for the kit will reimburse itself very quickly...
Just my 2 cents...

 

[thaung]

Thank you for the reply.

Well, going through a calibration of that magnitude is not an option, I truly don´t have neither the time nor motivation to take on such a task. When I print VC papers using a condenser setup I have a set of Ilford filters I use and that works fine. If I can´t find some form of contrastgrade table for the CLS70 I simply wont use it for VC printing at the moment. It would be nice to att least have some values to start from instead of starting from scratch.

I am actually very satisfied using the M800 with a condenser setup it´s just that I thought it would be nice to compare prints using a diffusion setup. Oh well, it´ll work out somehow.

 

[MattKing]

A quick test that would tell you a lot would be to do test prints with the Ilford filters (1, 2, 3 and 4?) and then some test prints at some maximum, middle and minimum settings on your colour head.

Then compare the results.

If you did 4x5 tests, three 8x10 sheets of paper would tell you a lot.

 

[JBrunner]

You could simply use split grade printing. It's not any harder than tuning in a print using filters.

 

[bdial]

What I did when I was using my Durst was come up with a conversion factor, starting with the assumption that the max was roughly the same. So for example 1 step on your M800 is 1.3 steps on the ilford documented scale (130 max).
Thus, in that case the Ilford numbers would be divided by 1.3 for your M800. You could fine tune by making some test prints at the perspective settings and comparing them with test prints made with the Ilford filters.
However, in the end, it's really arbitrary anyway. the great value of VC papers is that you do not need to think in terms of grade 1, or 3 or whatever. Rather, subtract yellow and add magenta to increase contrast and add yellow and decrease magenta to reduce it. You can perfectly well calculate some reference points and then just print. It doesn't really matter if your caclulated grade 2 setting is "really" grade 2, or 1.5, or 2.376.

That said, I'll second Jason's suggestion and recommend that you just use split grade. I am finding that my prints are way better doing that than using grade numbers at all. If you're careful and have locked the head (which you should do anyway) moving the dials doesn't impact the exposures. I have the MG filters, but find using the color head to be much more convenient, even for splitting.

 

[Mike Wilde]

I work with expired paper that people gift to me. Old VC paper, when not fogged, behaves differently than when it was new. No one can tell me how it reacts, and the fixed grade gelatine filters do not match with it's best possible performance any more.

Gee, I can hear the ghost of Fred Picker in my head right now when someone asked him what to do in such a situation: Test It Yourself.

I go though printing a a set of step wedges at different filter settings. Typically 13 or 14. They are not large. I have a 6x6 31 step format wedge from Stouffer. Best $50 I ever spent in darkroom gear.

I print the projected wedge at almost 1:1. This way the results can be labelled and taped into my printing notebook on a single page, and the table of readings that are taken from what they show go on the opposite page. I label them on the back with the filtration they got with a sharpie as I expsoe them, and process them all at once to keep the development variables the same. It takes up a single piece of 8x10 paper.

Typically for a 0-170 range head I will go all magenta from max to 140, 105, 70, 35, 15, to 0 then start to dial in yellow 15, 30, 70, 105, 140 and max. I have used this for 0-130 heads as well, with adjustments in the mid range filter settings.

This testing yield chips that once dried and ordered can be visually examined to tell you what the first non white step is, and first not totally black step is for each filter setting.

I use this, along with a do only once for a given enlarger test, to see what filter setting of equal m, y and c gives you a third of a stop of less light transmittancy.

This information allows you to construct a table of adjusted filtrations that lets me keep the same exposure time for first non white print tone when I change filter settings. It can also be used to do the same thing for a constant mid tone across varied filtration, which could be more useful if you do a lot of portrait printing.

All of this came from ideas posted to this site a number of years ago by a now departed poster who went by the name 'noseoil'. Describing this takes more time than actually doing it once you are used to the proceedure. I use it to build a custom filter setting table that gets pasted onto the front of each different old VC paper that I have to work with.

 

[thaung]

Thank you all very much for the advice given during the time I´ve been away. I have not had the time yet to make any serious atempts to understand this colorhead. Although I did try the conversion factor experiment suggested by "bdial" and that was a good startingpoint to figuring out rough contrast settings. Using this conversion-method (from 130 in my case) is probably not so very far off actually. More tests will be conducted when I´ve got the time.

Split grade printing is also a good idea by the way, I used that a bit when printing on my (now sold) Focomat V35, it was a good way to get great tones but I found it a bit time (and paper) consuming when trying to figure out the exact time for the different exposures needed for each neg printed. After using that technique I instead went on fine tuning my exposure (in camera) and development instead and trough that getting negatives that pretty much always could get printed using normal grades (1.5-3). That said, I do think that spit grade printing is hard to beat when printing difficult negatives.

Once again, thank you all so far for the knowledge and know-how you have shared, it´s been much appreciated.

 

[ic-racer]

The table in the CLS70 manual is not exactly what you want, but it gets you most of the way there. If you use individual M or Y filtration only, you can read an exposure factor off the table.
For example your non-filter print (around grade 2) looks flat but is exposed correctly at 10 seconds.
From the chart, if you use, say 25 Magenta, for the next exposure, you would increase to time to 13.1 seconds.
If you use 50 Magenta for the next print, you would use a time of 15.2 sec, etc.

Likewise if your initial print is too contrasty, and you wanted to use 50 Yellow for the next print, you'd use a time of 11.5 sec.

You may prefer to have a constant time for each contrast grade (I do). Rather than making a whole new chart ((there was a url link here which no longer exists)) I'd just use the table with the ILFORD paper that shows max of 130 and tweak the values in the table from there. Remember adding the same amount of both Y and M makes the print lighter at the same contrast and so on.

Making two exposures when you could make one makes the process more complicated, not less. Also, fiddling with the dials from 0-100 4 times for a single exposure may drive you crazy.

 

[JBrunner]

You can use two pieces of opaque whatever and by moving them at intervals during two exposures on one paper get a large checkerboard of possible exposures on that paper. That's what I do, anyway. Usually. never takes me more than two more papers after that.