Question for those who've used the Chromega Subtractive Color Calculator

For those who've used this or have one I hope that you can answer a question for me.

The directions say to add the filters shown in the chart to your existing filter pack to make the correct print but I'm wondering what if you need to subtract an amount of filter? I don't see any directions for removing some amount of yellow or magenta, only adding to what you already have.
I've highlighted the text where it says to add the filters to your existing pack and i'm at the point where I need to add per #45 on the chart; 5M + 10Y

Well if the pack you used to test was 50M+50Y and your results say to subtract 10M and 5Y then your new pack is 40M+45Y. I don't see the problem. Your new exposure time would be a little shorter. If when you add those filters you multiply by say 1.4 for your new pack you could try to DIVIDE by 1.4 to get you new shorter time. Should be pretty close.

darkroommike said:

Well if the pack you used to test was 50Y+50M and your results say to subtract 5Y and 10M then your new pack is 45Y+40M. I don't see the problem. Your new exposure time would be a little shorter.

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The problem is that it doesnt talk about subtracting...it says "add the filters to the filter pack already in use" see the words i highlighted in yellow

rpavich said:

The problem is that it doesnt talk about subtracting...it says "add the filters to the filter pack already in use" see the words i highlighted in yellow

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If you can not find ANY results on your calculator that subtract you could always make another test with less INITIAL filtration and use the calculator to figure out how much to add. I'm not a big fan of such visual calculators for this reason. Get a set of Kodak Color Print Viewing Filters and learn to use them rather than rely on your comparator. (BTW how do you know the visual comparator in the set hasn't faded after 30 years?) Find copies of the Two Bob's books on color Printing. Color Printing by Bob Mitchell and Color Printing by Bob Nadler. You might also look for Kodak's Bigger and Better Enlarging.

darkroommike said:

If you can not find ANY results on your calculator that subtract you could always make another test with less INITIAL filtration and use the calculator to figure out how much to add. I'm not a big fan of such visual calculators for this reason. Get a set of Kodak Color Print Viewing Filters and learn to use them rather than rely on your comparator. (BTW how do you know the visual comparator in the set hasn't faded after 30 years?) Find copies of the Two Bob's books on color Printing. Color Printing by Bob Mitchell and Color Printing by Bob Nadler. You might also look for Kodak's Bigger and Better Enlarging.

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So you dont own one of these?

Not any more, I tossed the stupid thing when I got a set of Kodak Color Print Viewing Filters. (I kept the integrator as I recall.) I do know how it works, though. I've also used the very similar Unicolor comparator. (I suspect that both were designed by Bob Mitchell, he was something of a guru for all of us printing color in the 70's and 80's.) I also have two color analysers and a densitometer. None of that makes you a better color printer. The problem with a comparator like the kit you have? Unless you are using the comparator to analyze a gray card your results will not be accurate, if you are using a gray card target your results will be good but only for images taken under the same lighting conditions.

darkroommike said:

Not any more, I tossed the stupid thing when I got a set of Kodak Color Print Viewing Filters. (I kept the integrator as I recall.) I do know how it works, though. I've also used the very similar Unicolor comparator. (I suspect that both were designed by Bob Mitchell, he was something of a guru for all of us printing color in the 70's and 80's.) I also have two color analysers and a densitometer. None of that makes you a better color printer. The problem with a comparator like the kit you have? Unless you are using the comparator to analyze a gray card your results will not be accurate, if you are using a gray card target your results will be good but only for images taken under the same lighting conditions.

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It doesn't sound like you are describing what I have.

rpavich said:

So you dont own one of these?

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Subtractive colour are you using a colour enlarger with dials for filtering or are you using under the lens filters.

If using a colour enlarger with dichroic Magenta and Yellow filter then making a Ring Around as suggested in another thread would be really valuable for you.

After 35 years of working on a colour enlarger , I never used anything other than the Y and M , The Cyan filter one was used for Nuetral Density or for Cross Processed negatives.

the higher the numbers in Y &M the colder the print, the lower the numbers the warmer the print.

Once you settle on a specific film and consistent developer for C41 your life will become much easier .... mixing films will give you starting balances that are quite different.
I used an analyser/translator at the very big labs I worked at to get starting balances, but only for first test. After first test with recorded settings I would go manual.
At large interneg Labs I worked at we never used analysers as each emulsion would give predictable starting balance.. These labs would buy 5000 4 x5 films at a time for consistency.

But at each place where I worked as a colour corrector and printer, I would make a custom ringaround and put it in the correction area. I would always use this for reference and I absolutely
made every technician I trained work by it.. Those who did not use the ring around for colour reference were soon to lose their jobs.

There are very few people who can fully understand colour theory as it applys to colour printing and as well very few that can work naturally without some help.
The visual filters recommended above are mandatory IMO for any colour worker, working manually under an enlarger. Highly recommended.

FYI most people do not have a great grasp on this, a well executed Ring Around can make Most People able to come within one point of colour accuracy if used properly .
My first year of colour work away from school was for a wedding studio that had inhouse printing. I remember for three years making corrections on tests and showing them
to my boss, who in three years rarely accepted my correction.

Over time I trained myself to see colour, but as soon as I got to be boss I made sure each colour station had a ring around.

Bob,
I'm using a Dichrotic head with dials.
I do have the kodak viewing filters and use them, and I do plan on making a ring around also, but since I had this and was messing with it, a question came up. I didn't want to turn this thread into a discussion about the merits of any one system...just had a question that occurred to me, that's all.

I appreciate the help.

They all work the same way, you use an integrator under the lens, make a print, compare the print to a standard gray scale, and then adjust filtration to achieve a "perfect" gray. These systems are ideal only if all you shoot are gray cards and all you print are gray cards. I have used one and quit using it. The Nadler book also mentions similar devices by Beseler, Colourtronic, DPC, and Unicolor Mitchell. I've attached the relevant page.

darkroommike said:

They all work the same way, you use an integrator under the lens, make a print, compare the print to a standard gray scale, and then adjust filtration to achieve a "perfect" gray. These systems are ideal only if all you shoot are gray cards and all you print are gray cards. I have used one and quit using it. The Nadler book also mentions similar devices by Beseler, Colourtronic, DPC, and Unicolor Mitchell. I've attached the relevant page.

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Thanks for the info...could we not turn this thread into an argument about about calculators? I just had one question...that's all. I have no horse in the race, I don't care what anyone uses to get a print...I really don't.

Here is how I was taught to colour correct manually

make a test print
First and foremost the correct density is what you want to achieve as colour will change dramatically with density.
Once you have your density what we would look for was CAST which usually could be magenta cast , green cast , yellow cast or blue cast. or a combination
Once you have adjusted your filters for the cast , you have figured out all your dodges and burns.. These will have an effect so do them on your tests.

Then we would look at the print and determine if we want to COOL THE PRINT with Cyan equal Plus Y & M or WARM THE PRINT with equal Minus Y & M

At all times I would only be adjusting the Y and M filters never Cyan. few exceptions.

When learning it could take one about 3-5 tests, I would be surprised if when starting you can get away with less tests. Once you get rocking two tests will be possible then final print.

rpavich said:

For those who've used this or have one I hope that you can answer a question for me.

The directions say to add the filters shown in the chart to your existing filter pack to make the correct print but I'm wondering what if you need to subtract an amount of filter? I don't see any directions for removing some amount of yellow or magenta, only adding to what you already have.

Click to expand...

I use these and like them very much. I think they are better than Kodak viewing filters. Don't throw them out. They are great for starting out when you don't have any idea what to do. The answer to your question is that if you have to go down on Y or M, you will get a line in the chart that has a C. If you have to add 20C for example then you don't really want to ever add C, you just subtract 20Y and 20M from what you have. They explain this in a later note in the directions.

sfaber17 said:

I use these and like them very much. I think they are better than Kodak viewing filters. Don't throw them out. They are great for starting out when you don't have any idea what to do. The answer to your question is that if you have to go down on Y or M, you will get a line in the chart that has a C. If you have to add 20C for example then you don't really want to ever add C, you just subtract 20Y and 20M from what you have. They explain this in a later note in the directions.

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Ahhh, thanks.

Much appreciated.

Bob Carnie said:

First and foremost the correct density is what you want to achieve as colour will change dramatically with density.

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Just to be a bit contrary...
When I used to do a lot of colour printing, if I was having trouble getting a difficult negative right, I would try prints that were both too dark and too light. The too dark prints would accentuate colour casts in the highlights, and the too light prints would accentuate colour casts in the shadows.
Based on that information, I could often adjust the filtration to allow me to either eliminate the colour cast or, in some cases, allow me to choose which cast I preferred to keep (those wonderful multiple light source negatives).

MattKing said:

Just to be a bit contrary...
When I used to do a lot of colour printing, if I was having trouble getting a difficult negative right, I would try prints that were both too dark and too light. The too dark prints would accentuate colour casts in the highlights, and the too light prints would accentuate colour casts in the shadows.
Based on that information, I could often adjust the filtration to allow me to either eliminate the colour cast or, in some cases, allow me to choose which cast I preferred to keep (those wonderful multiple light source negatives).

Click to expand...

That sounds like a good method.