Are these color filtration the same

aca · Dec 15, 2021

Hello,

I am still quite new to darkroom color printing and with a lot of trial and error, I manage to get a "for me" good enough print. As I am reading up on the color printing theory I do have some questions which I like to ask you (all my film friends are b/w printers). Let's say my print is way too blue then I would add more blue to compensate.

a/ Now blue doesn't exist on my durst color head so we need to add a mixture of cyan and magenta to get less blue in the print, right?.
b/ Looking at the color wheel, can the same be accomplish by substracting yellow ?
c/ If so is there a general ratio between yellow and magenta/cyan? Say substracting 10Y = 5M/5C??
d/ Any good color printing book to get myself for Christmas?

Thanks for reading

AgX · Dec 15, 2021

There are two most different approaches to using light filter (be it optical filters or dyes in printng):

-) additive colour forming

White light of three sources is filtererd to form either

blue
gree
red

light.
These part then are added partially or in their whole to form any hue of light or white light

-) substractive colour forming

white light of one source is reduced

partially or in its whole
by

magenta
cyan
yellow

filters,
To yield any hue or black.

Thus in one case light of different sources is added. In the other case light of one source is reduced.

AgX · Dec 15, 2021

In analog colour photography today nearly always the subtractive approach is used.

The few exemptions are few enlargers that use the additive approach, obsolete colour materials, the latest was from the seventies/eighties, or specific subject lighting.

Mr Bill · Dec 15, 2021

aca said:
b/ Looking at the color wheel, can the same be accomplish by substracting yellow ?

Yep, you're doing good.

Regarding your question about equivalency, here's an older post where I worked through a couple examples. It's sort of tedious, but if you want to resolve things in your head it may help. Essentially, though, if you need something like a 10cc filter change, everything stays at a 10cc change.

https://www.photrio.com/forum/threads/filters-colour-absorption-question.52345/#post-765206

Ps, in light of what AgX has said, let me point out that I'm making an assumption that you are using a "subtractive" system, where you have a single light source, into which you insert color filters.

AgX · Dec 15, 2021

The problem in this thread is that the OP inquires about subtracting colour values.
However the graphic he posted depicts additive colour forming. Thus my post #2 of generic nature.

lantau · Dec 15, 2021

If you have any experience in adjusting the white point in digital imaging, e.g. in Lightroom, you'll find that this is just a representation of what has always been done on a colour enlarger.

You ignore that cyan dial, leaving you the magenta and yellow one. On the computer a program usually shows two bars.

The yellow-blue axis. That is your yellow dial on the enlarger. It will make your image more blue if you dial in more and more yellow when you dial in less
The magenta-green axis. The same using the magenta dial.
The cyan-red axis is applied by changing equal values on the former two.

That way you can cover all six colour casts, which your image can have. Four by single dial. Two by combining them.

perkeleellinen · Dec 15, 2021

This has always been helpful to me, I copied it from a post here on APUG many years ago:

-If print is too RED, dial +5cc MAGENTA and +5cc YELLOW, print will turn lighter
-too GREEN, dial -5cc MAGENTA, turns darker
-too BLUE, dial -5cc YELLOW, turns darker
-too CYAN, dial -5cc MAGENTA and -5cc YELLOW
-too MAGENTA, dial +5cc MAGENTA, turns lighter
-too YELLOW, dial +5cc YELLOW, turns lighter

MattKing · Dec 15, 2021

The other thing to be careful of, is that many people see magenta and think it is blue. Others see cyan and think it is blue.
So be open to the possibility that the adjustments you are trying are actually appropriate for a different colour cast than the one you actually have.
At least early on, it is worthwhile to make a fair number of colour ring around tests, until you get comfortable with this.
Some sort of proofing easel is really helpful with colour.

AgX · Dec 15, 2021

What do you mean by "proofing easel"?

Those filter sets to be placed on the paper?

MattKing · Dec 15, 2021

AgX said:
What do you mean by "proofing easel"?

Those filter sets to be placed on the paper?

For example, one of these Saunders units that allow you to put four identically framed images on a single 8"x10" sheet of paper:

The easel (and 4"x5" window) stay in the same place, while the paper gets moved from corner to corner by hand.
That photo is from the internet (ignore the lines added to the yellow background). I'd dig mine out except being as heavy as it is, I store it in the bottom of my darkroom accessory bin.
A Phillips test strip printer like the one shown in this post can also work, if you are set up a way of moving it to use the same part of the image for each test strip:
[URL="https://www.photrio.com/forum/threads/philips-darkroom-test-strip-printer-pvb100.42763/#post-2038957"]Philips Darkroom Test Strip Printer PVB100[/URL]

AgX · Dec 15, 2021

Sorry, these designations...had you said something like test strip easel/printer, there would have been a bell ringing at me...

aca · Dec 15, 2021

To all, appreciate all the input and suggestions (living in the Netherlands so I might score a Philips Test Strip Printer on the local ebay).

Speaking of Philips I know the Philips PCS 2000 uses RGB and 3 bulbs. Never tried the enlarger myself. I have only used Durst enlargers.

@perkeleellinen tx for the info. I have been given this;

@lantau thank you ..... seems to be corresponding with my image above

@AgX I was just in general wondering if substracting yellow would do the same as adding Magenta+Cyan (as these 2 make blue).

mtjade2007 · Dec 15, 2021

aca said:
c/ If so is there a general ratio between yellow and magenta/cyan? Say substracting 10Y = 5M/5C??

I think -10 Y = +10 (C/M).

koraks · Dec 16, 2021

aca said:

That's very useful - for Cibachrome printing. It's only moderately useful for RA4 printing, as you'd typically not touch the cyan dial when doing so. For RA4, it would be something like:
Yellow cast --> Add yellow
Magenta cast --> Add magenta
Red cast --> Add yellow + magenta
Cyan cast --> Subtract yellow + magenta
Blue cast --> Subtract yellow
Green cast --> Subtract magenta

I'd also refrain (at least at first) from adding/subtracting two colors at the same time (M + Y). It's generally better to develop an intuition/feeling of what a single filter adjustment does. Likewise, I'd recommend (again, at least initially) to not adjust exposure time and filtration at the same time - for the same reason.

When making adjustments for an initial test strip, don't hesitate to make big adjustments - like 10, 15 or even 20 cc. It's generally faster to overshoot your corrections and then work your way to the middle than to inch your way to a correct print. It's also 'safer' in my experience; if you make incremental adjustments (e.g. 4-5 cc at a time), there's a much bigger chance that you'll end up thinking "this looks pretty much OK, let's go with this" while in reality the print might have benefited from some further adjustment. By having more extreme end points at hand you have a broader and more solid foundation to base your choices on.

As to books - I don't know, but I'd recommend getting a nice roll of paper to play with: experience is priceless

PS: I see we're from the same country; as soon as I have my darkroom up and running again (I'm in the process of moving house) feel free to drop by. I'm at approx. 1h15m drive from you.

RalphLambrecht · Dec 16, 2021

aca said:
Hello,

I am still quite new to darkroom color printing and with a lot of trial and error, I manage to get a "for me" good enough print. As I am reading up on the color printing theory I do have some questions which I like to ask you (all my film friends are b/w printers). Let's say my print is way too blue then I would add more blue to compensate.
View attachment 293263
a/ Now blue doesn't exist on my durst color head so we need to add a mixture of cyan and magenta to get less blue in the print, right?.
Another reason why I stick to Viking White printing. Three colors amore than my brain can handle.
b/ Looking at the color wheel, can the same be accomplish by substracting yellow ?
c/ If so is there a general ratio between yellow and magenta/cyan? Say substracting 10Y = 5M/5C??
d/ Any good color printing book to get myself for Christmas?

Thanks for reading

aca · Dec 20, 2021

@koraks thanks for your explanation, info and offer. Those last 3 color adjustments will help a me a lot.

Hopefully, we have a more open society next year

Sirius Glass · Dec 20, 2021

I use Yellow and Magenta. I first use Magenta and get the exposure correct with that filter. The I repeat that and work on Yellow. That gives what is call split filtering and sometime I find that using Magenta alone will be "good enough" or "great".

This is from Ilford Multigrade Papers

aca · Dec 20, 2021

Sirius Glass said:
I use Yellow and Magenta. I first use Magenta and get the exposure correct with that filter. The I repeat that and work on Yellow. That gives what is call split filtering and sometime I find that using Magenta alone will be "good enough" or "great".

oh, definitely going to try your workflow as well. Thanks for sharing!

Sirius Glass · Dec 20, 2021

aca said:
oh, definitely going to try your workflow as well. Thanks for sharing!

See the inserted table.

aca · Dec 20, 2021

Sirius Glass said:
See the inserted table.

Oh but that's is what I use for b/w multigrade paper printing .......... that's not the same for color printing?!

Sirius Glass · Dec 20, 2021

aca said:
Oh but that's is what I use for b/w multigrade paper printing .......... that's not the same for color printing?!

Those table are for black & white only.

DREW WILEY · Dec 21, 2021

Very very few people have serious RGB additive enlargers like I do, so this whole thread can realistically be simplified down to CMY subtractive methodology, and apparently in this case to color negative enlarging for sake of RA4 printing on ordinary chromogenic papers. But now this thread has gotten potentially confusing by bringing up all kinds of irrelevant information concerning VC black and white papers, discontinued Cibachrome, etc. He asked about COLOR PRINTING. And undoubtedly being a color NEGATIVE process in mind, the rules are quite simple :

To make a print more yellow, LOWER the yellow setting on the colorhead; for more cyan, lower C on the dial; for more magenta, lower the M setting.

Directly across the color wheel, in artists terms : For more blue, lower both M and C equally; for more red, lower Y and M equally; for more green, lower Y and C equally.

Or to increase anything, rather than lowering it, just do the opposite. After a little practice, this all gets intuitive.

koraks · Dec 21, 2021

No need to touch the cyan dial with RA4 printing...

Sirius Glass · Dec 21, 2021

koraks said:
No need to touch the cyan dial with RA4 printing...

Using cyan just adds a neutral density filter when combined with yellow and magenta.

DREW WILEY · Dec 21, 2021

If you're going to give that "don't touch cyan" advice to a beginner, you need to spell out why (e.g., recommended Y&M starting filtrations, C = 00, when doing RA4 test strips, how to compensate for lack of cyan using the other two settings plus/minus, etc.). Basic color theory first. Get on first base first. Start with a master test negative including a neutral gray scale to calibrate each batch, etc.

But in short form, if you feel you need to add cyan to get the correct color balance you need, just subtract an equivalent amount of Y & M instead, or visa versa. Then figure out the balance mathematically. For example, if your test print looks about 5 cc too much green, that informs you to add 5cc cyan plus 5 cc yellow to your STARTER setting of, say, hypothetically, 00C, 50 Y, 50M. And this would mathematically equal 05C / 55 Y / 50 M. So to avoid a little neutral density, just SUBTRACT the LOWEST AMOUNT equally from each of them, namely 5cc, leading to a net exposure setting of 00C / 50 Y / 45 M.

But in the hypothetical case I just noted, it would have been simpler just to recognize that green is directly across the color wheel from magenta, so by decreasing M when working with color negatives, you're decreasing green in the print itself, and a 5cc less green in print correction would therefore come out the same net exposure setting as above = 00C / 50Y / 45 M.

This all sounds counterintuitive and should, because unlike mixing paints, we're talking about printing negatives in exactly the opposite manner, in relation to subtractive colorhead filters. Refer to that handy chart ACA posted already, which spells it out in simple terms. But don't get confused with the irrelevant VC paper charts or Ciba printing formulas on other posts.

Are these color filtration the same

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Are these color filtration the same

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