Max grade from colour heads

whojammyflip

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Hi, I've got both a LPL 7700 and a Kaiser VPM enlarger, and with a Stouffer step wedge, dont seem to be able to get higher than contrast of about 3. I dont know whether I am being too brutal in my judgement/seeing tones which dont really qualify as tones though. Has anyone else tried calibrating their prints using a Stouffer step wedge?

My definition of the first non pure white tone is that I can see a boundary between the step and the last white tone, and for the z1, near max black, I can still read the Stouffer numbers. I'm using the step wedge T2115, which I guess stands for 21 steps at 0.15 log10 density units. I dont seem to have any problem getting very long tonal ranges though out of the LPL 7700 it looks like I can get a huge density range. I'm using relatively fresh MG developer for 1 minute in trays, and a mix of pearl and gloss MG IV paper. I'm wondering whether I should just use the filter tray in the Kaiser enlarger and Ilford filters.
 

ic-racer

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If you can't get grade 5 something is wrong.

Are you pressing the step wedge tightly against the paper?

Is any white (green) light leaking around the magenta filter; does it completely cover the light path? No cracks or chips?
 
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cliveh

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It sounds like you need to adjust your original exposure and development of the film. If you get this right, you shouldn't have a printing problem with contrast and no need to use printing filtration.
 

Jim Noel

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The maximum contrast range with subtractive light color heads has been shown to be about Grade 1 to about grade 3 1/2.
 

Sirius Glass

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Using the Superchromega Dichroic II head, I have gotten higher contrast with the yellow and magenta filters than I have with the magenta filter alone, but the exposure takes much longer to have similar development times. And no I have not taken the time to scientifically measure this because I so rarely need that high a contrast unless I am doing split filtering and because going to all the trouble to test would not provide that much useful information.
 

RobC

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Jim Noel said:
The maximum contrast range with subtractive light color heads has been shown to be about Grade 1 to about grade 3 1/2.
Click to expand...

This is totally wrong. I can get the full range from 00 thru 5 with my durst L1200. Some LPL enalrgers may only go to grade 4. I have no idea about other enlargers.

And yes I have done proper tests with stouffer step wedges and densitomter and very fresh paper ordered direct from Ilford. Old paper will completely screw up your results of a paper contrast test.

To the OP.

The range from paper density is from 0.04 to 90% of max density, so thats from a tad of very light grey to not quite max black.

The exposure range for this measurement is for G2 = 1.1, G3 approx 0.8, G4 approx 0.6 and G5 approx 0.4.

SO for G2 that would be just over 7 steps of your step wedge, for G3 just under 6 steps, G4 4 steps and G5 just over 2 steps.

Using a step wedge with 0.1 steps makes it easier to be more accurate.

Also

if you can measure print densities with a densitometer and plot charts in excel, then will be able to read off more accurately the grades you are getting and find where your paper contrast curves cross and hence the speed point which is useful for predicting what a change in paper contrast will do.
 
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paul_c5x4

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RobC said:
This is totally wrong. I can get the full range from 00 thru 5 with my durst L1200. Some LPL enalrgers may only go to grade 4.
Click to expand...

I did a test a while back with both a CLS450 head and a condenser head on an L1200 - Both were quite capable of hitting grade 5. I didn't test for grade 00 though.

hoojammyflip: Assuming your paper & developer are both fresh, I'd recommend trying a new lamp - When I had a C7700, I started getting muddy prints and couldn't hit the harder grades. Changed the lamp for a new one, and immediately noticed a vast improvement in the prints. Looking at the specs on these lamps, they generally have an operating life of just 50 hours, beyond that point, the quality of light starts to degrade.
 

bdial

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When I got my LPL 4x5 with it's color head I made a series of prints from a familiar negative using each MG filter, and another set using Ilford's recommended settings for yellow/magenta combinations.
The result was the color head prints were about 1/2 grade less contrasty than the MG filter prints. That is, the grade 3 color filtration print matched the grade 2 1/2 MG filter print.
The max was about grade 4, as I recall.
I never tried to fine tune the filter settings and I just print to the contrast I want, it's never been a problem.
 

RobC

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Yes its not critical or necessary to be able to print a test that produces a G5 curve. And if your enlarger is only capable of G4 you can always increase your neg development to match what your enlarger can do so that you can get just as much print contrast in a real print as I would with my enlarger. And the by product of that is that you may get 1/3 or 2/3 stop more film speed too becasue you are developing film to a higher contrast.

So its swings and roundabouts and you shouldn't worry about it unless your neg dev combined with enlarger contrast is not capable of getting a good contrast print. The actual Grade numbers are irrelvant with VC paper.
 

Photo Engineer

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Grade and contrast are two different "animals".

Contrast is the slope of the curve, and grade is the integrated contrast of a given slope including toe, mid scale and shoulder.

PE
 

Bill Burk

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paul_c5x4 said:
...I'd recommend trying a new lamp - When I had a C7700, I started getting muddy prints and couldn't hit the harder grades. Changed the lamp for a new one, and immediately noticed a vast improvement in the prints...
Click to expand...

I've got a color head that doesn't go to 165 M so if I were to use it for multigrade printing, I'd seriously consider getting a single filter: 100M (or 40M or something like that). Then I'd dial in the equivalents for 00 to what I could reach by the colorhead, and when I need more contrast, drop in the Magenta filter and recalculate.
 

RalphLambrecht

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I did thi a lot with my Durst L1200 head and got all the way to grade 6! with full magenta and no yellow.You should ha ve no issue to get to grade 5.If you do,You can always switch to under-the-lens contrast filters but I doubt that you'll need to.
 
OP
OP

whojammyflip

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Thanks for the responses. Reading through this, I am left wondering whether my developer is out of date. I think the developer is under a year old, but certainly its been open for over 6 months, prior to running these tests. I'm holding my print developing times constant at 1 minute per the Ilford instructions. The bulb is a new 100w dichroic Xenophot from Osram. I also wonder whether I have an invalid definition of what counts as the first non white and the last non black, as there is a lot of uncertainty there, and I cannot be more accurate than +-1 step, which is percentage wise quite a large uncertainty for the grade 5 test strip.

At the end of the day, if I can cater for a range of negative densities from 2.0 through to 1.0, I guess I should be capable of developing negatives so that they have that range. I'm only using 35mm and 120 film, so I dont really have that much flexibility to customise my development, unless I shoot a whole roll in one outing and remember what the light was like by the time I actually get round to taking the film out of the fridge and developing it.

I recently ran through a test set of negatives I had shot from zone 1 through 9 and surprised myself that my CI was only 0.45. This would mean that I would have to use grade 5 on my enlarger to get from min white to max black, I think. 0.45*7*0.333= 1.05.
 

DREW WILEY

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One of my colorheads will go clear up to 200M; but that's past the limit of any VC paper anyway. Just expose the paper thru a deep blue 47
or 47B color separation filter if you want to see how far it will go. Just be aware that some VC papers won't achieve DMax unless there's at
least a bit of token exposure to the low-contrast layer too.
 

RobC

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hoojammyflip said:
I'm holding my print developing times constant at 1 minute per the Ilford instructions.
Click to expand...

Just to be sure, you are using RC paper and not FB? For the latter I would be using a dev time of more like 3 minutes.

AND

If you print developer is colder than recommended print time will likely require extending. Its important to give full print development to get a true max black and therefore full contrast range.
 
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RobC

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It should be noted that the ISO(R) that any paper delivers is very dependant on the particular paper, its age, the filtration being used and the developer and devlopment conditions its developed with (time and temp).

From this you should gather that there is a fairly wide target area. The manufacturers aim (I think) to get within the ISO(R) standards for grades but your equipment, materials and processing may not and are very unlikely to be the exact same as manufacturers.

If you look at Ilfords MGIV data sheets you find that ISO(R) figures they give for Grade 2 are:

MGIV RC Grade 2 ISO(R) 110
MGIV FB Grade 2 ISO(R) 100
MGIV Classic FB Grade 2 ISO(R) 95

Those are the figures they get, presumably with Ilford filters and developers. My own test with MGIV FB (NOT RC paper) gave me an ISO(R) 110 for G2 which matched my test with zero filtration almost exactly (but I wasn't using Ilford developer). YMMV

The point being that these are ball park ranges and not set in stone as exact target numbers.
 
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Stephen Benskin

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RobC said:
The point being that these are ball park ranges and not set in stone as exact target numbers.
Click to expand...

Very true. That's another place where Adams drops the ball. He never really defines matching the negative to the paper. But as Jones has pointed out, depending on the subject matter and intention of the photograph, matching doesn't necessarily guarantee an acceptable print. It's just a good starting point. In my opinion, in order for the negative testing to have any real meaning, the paper should be tested first.

I once created a program that would determine the settings for the different paper grades from around five tests. Ralph's book, Way Beyond Monochrome, has a non program version that might be of help.
 

RalphLambrecht

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very true.I give RC paper 90-120s in the developer.Increasing paper development will increase max black and contrast with RC and FB paper until highlights get 'dirty' at which point development time is too long.
 
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