RA-4 filtration

elerion · Jun 19, 2017

I got some not ideal negatives from my last session. I think it could be due the blix not being in perfect state.

I got a yellowish and a bit reddish negatives.

Using a color analyzer, and a reference negative/print pair with a known filtraton, the analyzer tells me to use a lower yellow than zero. In other words, I'm not able to null the yellow dial in the analyzer.

I interpret this as a lack of yellow in the print.
I tried increasing magenta and cyan (which should be like increasing blue, which at the same time would be like decreasing yellow), but the analyzer didn't show any improvement (even, the other way round I would say).

I'm relatively new to RA4.
Could I just increase exposure, up to the point where yellow dial is nullified, and increase magenta filtering to compensate?
To better explain myself, this are the numbers.

I currently get (in analyzer color units, not enlarger units):
Y = -3 (three points are close to one stop of light)
M = 0

My enlarger is set at:
Y = 0
M = 50

I cannot decrease Y any further (my enlarger filtration is at zero for Y)
Could I just overexpose one stop, then add more magenta.
Y = 0
M = 70

I get this filtration from adding three points for Y and M in my color analyzer.

Thank you for your patient reading

Mr Bill · Jun 19, 2017

Hi, I don't follow how your analyzer reads, but how about just doing this: pick an arbitrary number, say 30cc units, and add this much to all three colors on your enlarger, cyan, magenta, and yellow. (This is equivalent to adding 30cc units of neutral density.) Now you have some headroom for further adjustments to yellow. Note that you also have to increase exposure to counteract the neutral density.

Your first step, when you could not remove more yellow, of increasing both magenta and cyan, should have also been correct. My suggestion to just add neutral density, in the form of all three colors, just makes things more clear.

elerion · Jun 20, 2017

Thanks, better than what I was thinking to do.
The strange thing is that my color analyzer, which seems to work fine (and reacts to C, Y, M dialing on my enlarger) shows an increase of Y when I add C and M on the enlarger. This doesn't make any sense, does it?

rpavich · Jun 20, 2017

What color analyzer are you using?

elerion · Jun 20, 2017

Beseler PM1A

rpavich · Jun 20, 2017

elerion said:
Beseler PM1A

Thanks.
OK, I think I understand what you are saying. You have zero on the yellow and cannot add anymore but your analyser is telling you that you should add yellow.

I'm actually doing this currently in some negatives right now.

As the other commenter said, to get some yellow headroom, add magenta and cyan and that will allow you to adjust the yellow. If you're currently getting:

Y = 0
M = 70

Then this is exactly the same:

Y = 10
M = 80
C = 10

When you do that, you are essentially engaging a neutral density filter as you are adding equal amounts of all colors so you are blocking more light, but it does allow you some leeway in your yellow adjustment.

Your numbers are very very close to what I'm getting right now on my negs.

EDITED TO ADD: after typing this I see that Mr. Bill said it much better than I did...sorry for the repeat of his post.

rpavich · Jun 20, 2017

elerion said:
Thanks, better than what I was thinking to do.
The strange thing is that my color analyzer, which seems to work fine (and reacts to C, Y, M dialing on my enlarger) shows an increase of Y when I add C and M on the enlarger. This doesn't make any sense, does it?

Mine does the same thing (but only a light or two)

rpavich · Jun 20, 2017

PS: If you want the best tip for getting spot on color that I've seen it's this: Buy an Expodisc and use it as a reference frame every time you shoot a new roll in whatever light you are shooting in. Make it the first shot. (you shoot it at the light source) Then dial the filtration using that frame for those shots. When you are out shooting and the light changes...shoot a new reference frame.
It's amazing. You get one-shot color that way. The ONLY thing that you have to do a test strip for is the density.

elerion · Jun 20, 2017

rpavich said:
PS: If you want the best tip for getting spot on color that I've seen it's this: Buy an Expodisc and use it as a reference frame

Using a color analyzer, isn't it?

rpavich · Jun 20, 2017

elerion said:
Using a color analyzer, isn't it?

Yes...actually. I guess I wasn't clear. I meant "if you want the most fool proof way to USE a color analyzer to get perfect color in one shot" then use an expodisc.

Basically it goes like this; instead of having a "green grass" standard or a "red" or "blue" standard to adjust your filtration, (or even the stock negative) you do the following.

Adjust the machine to get a perfect grey swatch from an expodisc frame or a frame from a grey card, or in your case the supplied neutral grey negative.
once you have that the machine knows what grey is.

Then when you go out to shoot, instead of worrying about having some known color in your shot and using that as a reference, you shoot one expodisc shot as a reference and as long as the light doesn't change (like you move inside or it clouds up or something) you are good to go. When you get home, you put any negative you'd like to print, get it set for framing and focus and all that, and then slip in the expodisc reference frame and using the enlarger filter adjustment you null the analyser to that negative. Now that negative should have perfect color for those conditions. All you have to do is make one test strip for density and you are done; you make a final print.

Here are two things I learned from Mick that are invaluable.

First is the expodisc instructions:

My suggestion is to find a Wallace Expo Disc, place that on the end of your lens, point the lens towards the light source. Put the camera onto automatic, take a shot. Then take any amount of pictures in that light and with that film. The Expo Disc makes a perfect grey card negative.

In the darkroom, find an image you like on that roll of film, then get a perfect colour print. Then without changing anything, place the Wallace Expo Disc negative into the enlarger, place the Colorstar analyser probe in the centre of the projected grey. Turn the lights off, then adjust the Colorstar sliders or wheels (different models) until all the lights go out. Then adjust the time on the analyser until it is the same as your time for your perfect print negative.

Your analyser is now perfectly calibrated.

Next time you are out, place the Wallace Expo Disc on the camera, take an automatic exposure towards the light source.

Develop the film.

Place the grey Expo Disc negative in the enlarger, turn the lights off. Place the probe into the projected area, switch the enlarger on, the darkroom lights off, then adjust the enlarger until all of the Colorstar lights go out. The Colorstar will also give you an exposure time, which will usually be very close, if not on the money. Take any negative shot under that lighting, and, apart from density change (enlarging time), you should have a correct colour picture.

Please note; you use two filters in the enlarger head, Yellow and Magenta. The third colour, Cyan, is not used. Less Cyan equals more red, more Cyan equals more Cyan. In colour printing, the third colour is obtained by exposure. If you are extremely close in correct colour, the darker you print, the more red the print will be. The lighter you print, the more Cyan (or less red) the print will be.

Next is the tip for changing enlargement sizes.

A quick tip. If you have made a very successful print, but wish to either make a bigger or smaller print, then density change is all that is required. For spot on density changes, this is how I do it.

With the successful negative still in the enlarger, switch off all room and any colour darkroom lights.

Slide the negative carrier half out of the enlarger (or right out if required) then place the analyser probe under the projected and filtered light (with no negative inserted) adjust the Colorstar timer to the enlarging time you used.

Place the negative back in then adjust the enlarger up or down and do a reasonably accurate framing with the negative being pretty much focused correctly. Slide the negative out and then take a time of exposure reading, that is your new exposure time. The new time should be correct to a degree you may find difficult to understand why you weren't doing this ages ago.

All that is now required is to do critical focusing, then make your next print.

I do this for B&W enlarging size changes as well; works a treat.

Mick.

RA-4 filtration

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