C36 M40 Y8 effectively means that you are running filtration of C28 M32, the yellow is just adding neutral density.
Basically, adding all three colours at once, adds neutral density.
When I've used an enlarger with a 2 stop ND facility I always put the ND to one stop. That way I can either reduce or add up to one stop of ND to facilitate constant times.
There is nothing wrong, AFAIK, with running a Cyan Magenta filtration for RA4 printing. Most people use the Magenta and Yellow instead.
There is a possibility that when you change the ND filter, the colour filtration changes ever so slightly. After all you are moving filters in or out of the light path!
I have a Philips colour analyser PCA 061. This may or may not be the same as yours. Unfortunately my enlarger and paper are different. I suspect the analyser may be different. If it is then you may need to ignore the rest of this post. If it is the PCA061 then how do you measure the exposure? On mine, once the analyser is calibrated the cyan button is depressed to determine the exposure and the Y and M buttons are depressed to determine the colour balance which is done by nulling the needle via the dichroic head. I take it we are talking prints from colour negs hence your mention of RA4 paper.
My PCA 061's needle is very sensitive and you're right it needs a few seconds to settle down. With changes of enlargement I have noticed that the Y and M settings will vary a little but not enough to alter the colour balance noticeably unless you were to look at the two prints side by side. Then if your eyes can detect very slight differences you may notice it or you may not.
If it is the PCA 061 then the needle is very sensitive and can take a while to settle down and I suspect can change just a little between the same neg even at the same enlargement. At least with mine it can but the change which might be say 2 on the Y dial really isn't detectable to my eyes although as I said to others who view the prints from the same neg at this difference it might just be detectable.
To avoid this just note the settings at say 5 x 7 and repeat at 10 x 8 instead of trying to use the analyser again.
Let us know if the analyser is the PCA061.
The example neg I am using is from a Holga and the film is Fuji NPZ 800. The neg is reasonable (for a Holga) and the chemicals I am using are pretty fresh in the Nova. The analyser I am using is the PCA 061 and that is partly the reason for the strange settings, plus the digipaper. With some playing I could get it back to the usual M Y combo but this paper is a 'Prototype' paper from Ilford. Ilford no longer do Ilfocolor/Ilford 2000 but they have Ilford Digital which is bought on a roll. I purchased a 50m roll 12" wide, I cut it to the sizes I need in batches. It has the same plastic base and is super glossy but the exposure setting have been tweaked for digital processors. That on top of the chemicals I am using (Speedibrew RA4) and I have some different settings for this compared to the Ilfocolor paper. i.e. there is hardly any yellow.
What I am unsure about, is how the filtering changes depending on the height of the enlarger head. It does not compute, the changes are small and can only be seen with the two prints side by side but they are there, both images would be acceptable but they are different. maybe yellow light is slower than magenta.
If you take out the cyan you should have plenty yellow. Cyan equals yellow + magenta. No?
I have used different papers with same chems and same papers with different chems and have never noticed the chems affecting the colour. The only factor affecting colour and therefore requiring re-calibration of the PCA061 was the paper. Fuji Crystal Archive required quite different calibrations from Kodak Endura. Once this was done, I quite frankly could really see a difference in the quality of the prints.
I'd be inclined to calibrate for each paper you use. When I calibrated, it results in the cyan dial being set for correct exposure and the cyan button being pressed for the exposure for each neg. The calibration of the Y and M dials are the only ones needed for colour balance. Cyan isn't needed at all except for exposure.
You can get test negs for various films such as Fuji or Kodak and test prints as well but any good neg you've taken will do as long as it has a range of colours and its of a scene where you can remember how the colours were. Once you have your print from the test neg looking like the test print provided, then that correct exposure and the Y and M dichroic head settings are left as they are and then used to null the needle by means of the Y and M dials on the PCA061. The exposure dial on the PCA061 is set to the correct exposure and the C dial nulled on this setting.
The analyser is now calibrated correctly. Throughout all of this the C dial on the dichroic head is left at zero and remains there.
As I said the needle is very sensitive and unless you have a lot of patience you may find that it settles at zero on a slightly different Y setting even if you were to remove the neg and then put the same neg back into the carrier and re-analyse. The difference in the print should barely be detectable.
I notice for instance that with a set of negs taken on the same film under the same exposure conditions each neg will give a very slight different Y and M readings. I always religiously analyse each neg but I strongly suspect that if I used the same setting for each neg taken under the same conditions then the prints would be almost identical and acceptable. I also suspect that the cheap one hour labs, for speed, used to use the same settings for the whole film. This often resulted in the odd print looking funny if the film negs were taken under different conditions where colur balance was different but most customers used to just shrug and accept it, probably thinking that it was their fault.
Do you have the PCA061 booklet? If not then let me know and I can photocopy it at my local library.
PM me with your address, give me a day or so and I'll post it to you.
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Wow, a lot of good advice there, I will need to go and play. I thought the chemicals would have an affect on the colour and density, if it doesn't.... GREAT. Just got two papers at the mo, the one I mentioned and a batch of Kodak Endura. So I will work on calibrating for those.
I do have a photocopy of the booklet for the analyser so I am okay there, but thanks for asking. Currently it is a new toy for me so I am still getting use to it and its quirks. Will have more of a play this weekend when I get my new chemicals in.
Bought a load of Agfa RA4 chemicals for 4x10 Litres including BLIX, stop and starter for £61 incl P&P so I am feeling pretty pleased. I think the guy still has some more if anyone is interested?
assuming the same batch of paper and time, the ND filter is not neutral.
Redo tests with using F4 and F11 or what is required.
Check with the analiser and ND in place. Then remove ND and close the lens to the same illumination as the set up. The rest of the filters should be the same if the ND is indeed neutral.
I think I have nailed this, need to experiment a little more but it seems to be the original RA4 chemicals I was using causing the inconsistency between each print I would put through the processor and so confusion. The Colour analyser also had a dodgy yellow dial as it probably hadn't been used in years (new eBuy). Taking the dial through the range a couple of times has helped and the guage will stay in one place rather than oscilate as before. Need to experiment a little more but it all seems to be going in the right direction.
High C business is sorted too, that was an issue with the carbon interface (me).
In printing RA4 the use of cyan except for neutral density is very strange indeed. I have printed color negatives since the 70's. I have NEVER encountered a situation where cyan filtration was required. Ordinarily the filter packs are just magenta and yellow with one of the two being in excess of the other. So mainly the filter pack is RED or the opposite of CYAN. Strongly do I suspect that something is wrong. How were the negatgives developed? ARE YOU CERTAIN THAT THEY WERE FULLY BLEACHED?
Claire (Ms Anne Thrope is in the darkroom)
He had something like
"C36 M38 Y0"
Take the C out it's likely something like M74 Y36.