Fastest way to set color filtration for RA4 printing

[sfaber17]

I think it would be worth sharing the method I used lately since it is better than some old threads on the subject. The first time I printed color, it took quite a lot of prints to get close. I was using a test negative that came with a color analyzer. It became clear that color analyzers didn't help much with converging on the initial filtration settings, just repeating them once you have a good print (maybe with a possible exception of the colorstar 3000). The colorstar 3000 has a way of measuring light through the print of a grey card to set the filtration, but it may take some iterations. I haven't tested that, but believe the use of color calculator filters is a better way. I used a Beseler Universal color calculator and a Chromega subtractive color calculator. They are matrixes of small color filters you set on the test print. You then use a diffuser (comes with the Chromega one) to mix the light of a typical scene so the net color should be close to grey. Then you pick out the grey colored spot on the print and use the correction values to adjust the filters. The Beseler one has course values, good for the first time when you may be way off, and the Chromega has fine steps, good for when you are nearly correct. I tried it when using a Beseler for the first time. I just set the filters for 90 and 60 similar to what I had on a Minolta enlarger. I put both filter arrays on the 8x10 print at f11 for 10 sec. The print came out purple. It isn't easy to tell the correction on that. It would be cyan and magenta or blue and red, so I needed more magenta and less yellow. The Chromega was off scale - no grey, but the Beseler had a grey spot at 40C and 50M. That meant I needed to subtract 40Y and 40M and add 50M, so I took a Beseler PM2L analyzer (which are a dime a dozen) and balanced it, and then dialed in 40 units less Y and 10 more units of M on the analyzer. I don't think the numbers on most enlarger filters are really correspond to density, hence the use of the analyzer. The arrays also have an indication of intensity. The Beseler matched one stop dark, and the Chromega reads out the time directly as 6 sec. So I stopped it down to f16 and took another test print at 10 sec. Since the jobo drum holds 2 prints , I just made a regular print as well. The test print was a light brown, much better, and the picture wasn't bad at all. The dandelions were a bit on the pink side but it dried out a bit more yellow. The Chromega array became useful now since its fine control predicted a change of 10Y and 5M. After dialing that in the prints came out just right. There are also Unicolor arrays similar to these but I found those to be not as nice and frequently faded, perhaps because they are in clear cases. I also think these work better than using Kodak viewing filters.

 

[btaylor]

I just started RA4 printing again after a 30 year hiatus. I couldn't find my old projection color calculators but I did find a set of Kodak viewing filters
with a color wheel. Using a negative I shot of a grey card and a starter filter setting of 50Y and 50M I got to the correct density and filter pack in about 4 prints. I was using the Arista Color paper from Freestyle. If you are wondering about that paper, the clerk said "it's made in the USA, and the only manufacturer of RA4 paper in the US is Fuji." It looks great. I have a color analyzer but I am too lazy to set it up and use it!

 

[sfaber17]

Not bad. I guess if you know the theory and have a bit of experience you don't need a lot of gadgets. I got a 20" roll of Fuji paper that must be hundreds of feet for $20. Made one print on it so far, hope it doesn't go bad. Now its time to try some big prints.

 

[bvy]

I use a homemade test print easel (basically just an easel with a cardboard guide and mask) which allows me to make four exposures of a scene to a single sheet of paper. So I find an area that has something gray or white, and I might expose it at 50M/50Y, 50/75, 75/75 and 75/50. From there I pick the closest one and do some further refinements varying by 5cc. If I have trouble, I might slap it on the scanner, take a RAW scan, then analyze it in a photo editor to see which is closest to gray. This actually works very well for me.

I also keep records of everything in an Excel spreadsheet and I try not to change my process. So for each print, I record not only the filtration and exposure, but the light in the scene (sunlight, overcast, camera flash, etc.) and the film used. When I want to make a new print, I can do some filtering and get a reasonable starting point.

Like you, I've not found the Kodak color viewing filters to be very useful. Maybe it's my eyes!

 

[Mick Fagan]

Kodak viewing filters do work, you sort of need a bit of practice and generally speaking you need to be reasonably close to the correct colour to be able to use their fine tuning capability.

Essentially you have your test print, either under a colour corrected light source, or under the same light the print will be displayed, or outside in good sunlight, (mid morning or mid afternoon is good) then you quickly flash the colour viewing filter strip in front of your eyes and remove the viewing filter strip in about 2 seconds. This removing the colour viewing strip in such a short time is required because our brains compensate and make automatic colour corrections in about 3 seconds if the colour shift is only minor, If the correction, or colour shift is major, you will continue to see that bias, but if it is a quite minor colour cast, the brain is super quick at making that cast dissappear. I usually will flash the viewing filter strip across my eyes at least half a dozen times, the idea being to ascertain the colour correction required, and possibly the amount of colour shift/correction required to get it on song.

Talk the viewing system out loud, as in: looks warm, is the warm red or is it maybe brownish (this is a warm colour). Is the red maybe a little pink? Is that highlight in direct sunlight (in the print) red or pink? Then make a decision. It's either red or pink (Magenta) so make a correction.

Be aware that the darker your print, the redder it will be. So if you determine a print requires say ½ a stop less exposure, any Red in that print will lessen and head towards Cyan.

Colour printing from a colour negative uses two filters in the enlarger head. You will normally use Magenta and Yellow which control most colours by you fiddling the filtration. Red is determined usually by density of the print once you start to get close to correct colour. Automated colour negative printing machines analyse a negative, then adjust the Magenta and Yellow in their system in conjunction with the amount of flash (strobe) time to get the correct density and at the same time get the correct red filtration in the print. If an automatic colour printing machine starts to go awry in flash time/power, then the prints usually come out quite light and Cyan coloured, or quite dark and Red coloured.

After making a decision that you have a cast, you need to ascertain what the cast is, this is where it can become quite tricky. It is hard to figure out if the cast is Red, or Magenta if it is reddish/redwarmish, if you get my drift. Magenta usually looks pinkish, so if you can see that the cast is reddish, but with a tinge of pink in anything white or very light coloured.. Then I would assume that there is a Magenta cast, and possibly a Red cast. Depending on the amount of pink, I may or may not assume that I need to do two corrections, one for Red, another for Magenta.

A possible correction when you are getting close could be, you need 5 units of Red taken out, plus 2 units of Magenta removed. I would then sit down and work out the actual colour units of each that I need to remove, adjust the colour head then adjust the exposure time for the removal of the filtration removed, then hit it and hope it is either perfect, or very close to what is acceptable.

One of the better ways is to work out what you need to do, write that down. Say you need to remove a red cast and lighten up the print 1/8th of a stop . Then, sit down and work out with paper and pencil just how you do the correction in the colour head and with the timer.

Also, other than Red/Cyan changes, I really have hardly ever had a colour cast happen because of timing changes, actually I don't even remember it ever happening. The longest exposures I have done were around 15-25 minutes for mural colour prints. Using the exact same paper and same developing machine, that paper produced perfect colour prints at around 2 seconds exposure. In my home darkroom, I would go from 12-15 seconds for a small print (or enlargement factor) to something like 128 seconds for a large print (or enlargement factor) using the same negative but just different print size or enlargement factor. Not once would I ever change the filtration and my home darkroom due to a change in exposure time. Also my colour prints were usually pretty spot on with regard to colour and density; subject matter aside that is.

Just a thought after reading what I have written but before I hit the reply button. I think some people get a little confused when they think there is a colour shift going to happen when the make exposures that are longer than what is their norm. They think this because they have read that there is a colour shift as exposures are longer or shorter. To a degree this is true, but realistically, the difference is usually miniscule and the home worker will hardly ever notice. A colour correction between 14 seconds and 128 seconds, could require 1 unit of Magenta change, or something like that.

Also, we haven't even touched on Yellow, Blue or Green casts, to mention just some of the other colours one can sometimes see in an uncorrected colour print.

Some thoughts, Mick.