Max grade from colour heads

RobC · Sep 9, 2015

RalphLambrecht said:
how so:confused:

You can waste a lot of time obsessing about the minutia when stepping back and getting the bigger picture right is all that is required.

My favourite quote:

Every man gets a narrower and narrower field of knowledge in which he must be an expert in order to compete with other people. The specialist knows more and more about less and less and finally knows everything about nothing.
Konrad Lorentz

Stephen Benskin · Sep 9, 2015

RalphLambrecht said:
it does!
maybe thisdoes too.one can never have too much information

How to determine paper LER is spot on for this thread.

Photo Engineer · Sep 9, 2015

RalphLambrecht said:
it does!
maybe thisdoes too.one can never have too much information

Ralph, this PDF file is an excellent article. I would like to state again that contrast and grade are not the same. Contrast is the slope of the straight line and grade is what you have defined in your article as contrast.

AAMOF, Kodak made 2 papers each with the same contrast, but the toe and shoulder differed between the photofinisher and professional versions. The amateurs wanted more snap and had more flare so they got sharper toes and shoulders, but the pros wanted long soft curves.

As a result, one paper was considered about grade 2.5 and the other about 1.5 but both had a mid scale of 2.5 when you measured contrast.

PE

RalphLambrecht · Sep 9, 2015

Photo Engineer said:
Ralph, this PDF file is an excellent article. I would like to state again that contrast and grade are not the same. Contrast is the slope of the straight line and grade is what you have defined in your article as contrast.

AAMOF, Kodak made 2 papers each with the same contrast, but the toe and shoulder differed between the photofinisher and professional versions. The amateurs wanted more snap and had more flare so they got sharper toes and shoulders, but the pros wanted long soft curves.

As a result, one paper was considered about grade 2.5 and the other about 1.5 but both had a mid scale of 2.5 when you measured contrast.

PE

thanks for your kind words; coming from you means a lot to me but,I have to admit that Mike Griswold from Ilford edited the article before t was published

Photo Engineer · Sep 9, 2015

Well, you see, we probably came at it from two historical or cultural standpoints. If Ilford never made 2 "grades" with the same "contrast" then perhaps the terminology would be different.

As for my words, they are sincere, but I am just another person here. I think Mr. Griswold might have a lot more to say on this as I am sure that he is another expert in the field.

PE

goros · Sep 10, 2015

RobC said:
You can waste a lot of time obsessing about the minutia when stepping back and getting the bigger picture right is all that is required.

My favourite quote:

Every man gets a narrower and narrower field of knowledge in which he must be an expert in order to compete with other people. The specialist knows more and more about less and less and finally knows everything about nothing.
Konrad Lorentz

How wise Mr. Lorentz was.

ic-racer · Sep 10, 2015

You need the Ilford 5 filter as a comparison for the test. Otherwise, yes, you are just guessing due to so few steps visible.

RobC · Sep 10, 2015

Stephen Benskin said:
How to determine paper LER is spot on for this thread.

I think what is most important for anyone using VC paper and filtration is that:

normal development prints well on unfiltered paper
nominal Grade 2 filtration settings print same as unfiltered
you have three evenly spaced grade increments above nominal G2. So G3, G4 and G5. Whether they actaully match ISO grades isn't so important, they just need to be evenly spaced which makes predicting what an increase in filtration will do much easier when actually making prints.
All the nominal grade settings create curves which all cross at same print density.

The only way to know this is what is happening is to use a transmission step wedge (preferably 0.1 density steps or smaller) and print at each grade setting and graph them.

The results you see in the graph visually tell you a lot about how your enlarger filtration is working. This is of much more use when something is wrong. If your enlarger is working perfectly fine and contrast increments seem to work as you anticpate, then you don't really need to do the tests.

But if an increase in contrast seems to throw off the print time and you are not sure about why or how far, then it may well be worth the time and effort to do the the tests. They will tell you the speed match point as well. That speed match print density is useful for determining what print density to set print time too as that that is the print density which will vary the least when you change contrast settings.

Knowing what the actual Log Exposure Range (LER) is not so important unless you are trying to match settings against the ISO standard which is quite a broad target anyway. i.e. not a precision target. Having said that, if you have a densitometer and can chart the step wedge print results properly, then you will be able to see what the LER is as a by product of the test. i.e. the test should be about understanding your enlarger settings and what effect they have and not about finding numbers.

So in this case a certain level of detailed knowledge is useful, but only if you are having problems with your enlarger filtration settings in the first place.

Roger Cole · Sep 10, 2015

goros said:
How wise Mr. Lorentz was.

His advice could transform your practice.

Ba-dum-ching.

Sent from my iPhone using Tapatalk and 100% recycled electrons - because I care.

ic-racer · Sep 10, 2015

RobC said:
normal development prints well on unfiltered paper

Unfiltered paper is an undefined entity and I'd not base anything on the results. Unfiltered paper results not transferrable A priori to the filtered grades due to variations in the illumination light source. I see no reason to ever use the paper unfiltered unless the filters are gone or broken.

RobC · Sep 10, 2015

ic-racer said:
Unfiltered paper is an undefined entity and I'd not base anything on the results. Unfiltered paper results not transferrable A priori to the filtered grades due to variations in the illumination light source. I see no reason to ever use the paper unfiltered unless the filters are gone or broken.

I see no sense in calibrating to an undefined finish point which isn't the print. You can't calibrate dichroic filters if you ain't using paper so by definition you have to use paper.

My view is that you take your standard paper (assuming you only want to do this once) and you calibrate to that since its the paper you will be using the most.

Being a zone system user (of sorts) I calibrate to my standard paper which happens to be MGIV and print zone system patches at G2 to prove to myself that my metering and development produces what I expect it to produce when I meter and place it on any zone. I would suggest that is as good if not better than just calibrating to an arbitrary number with no idea whether the full range of tones in your negative will end up where you think they will.
You can of course vary from that "starting point" when you get down to printing any neg but at least you will be starting from a known and fairly consistent start point.

As it happens MGIV printed without any filtration does actually produce what Ilford says it will produce which is a natural Grade 2 within the ISO(R) range so why not verify that with what the zone system predicts by actually using paper to prove it. If you happen to want to calibrate to grade 3 or any grade then you are free to do it.

YMMV

I would add that prior to VC paper all serious photographers would have been calibrating to paper even if they didn't actually do the contrast test.
i.e. they would adjust film development to get the results they wanted which is effectively calibrating to paper.

And I would add that calibrating to paper makes printing easier which is the main reason why its worth doing. It seems to me that exposing for the shadows and not calibrating to paper just makes printing far more difficult. Just doesn't make any sense to do it that way. Again YMMV.

DREW WILEY · Sep 10, 2015

I leave all that paper grade talk behind except for actual graded papers, and even then, the practical definition can differ among papers.
A simple printed test strip is worth more to me.

Sirius Glass · Sep 10, 2015

Grade 4.5 is the highest grade I can get with Ilford Multigrade RC paper.

Stephen Benskin · Sep 10, 2015

RobC said:
I think what is most important for anyone using VC paper and filtration is that:

normal development prints well on unfiltered paper

nominal Grade 2 filtration settings print same as unfiltered

you have three evenly spaced grade increments above nominal G2. So G3, G4 and G5. Whether they actaully match ISO grades isn't so important, they just need to be evenly spaced which makes predicting what an increase in filtration will do much easier when actually making prints.

All the nominal grade settings create curves which all cross at same print density.

The only way to know this is what is happening is to use a transmission step wedge (preferably 0.1 density steps or smaller) and print at each grade setting and graph them.

The results you see in the graph visually tell you a lot about how your enlarger filtration is working. This is of much more use when something is wrong. If your enlarger is working perfectly fine and contrast increments seem to work as you anticpate, then you don't really need to do the tests.

But if an increase in contrast seems to throw off the print time and you are not sure about why or how far, then it may well be worth the time and effort to do the the tests. They will tell you the speed match point as well. That speed match print density is useful for determining what print density to set print time too as that that is the print density which will vary the least when you change contrast settings.

Knowing what the actual Log Exposure Range (LER) is not so important unless you are trying to match settings against the ISO standard which is quite a broad target anyway. i.e. not a precision target. Having said that, if you have a densitometer and can chart the step wedge print results properly, then you will be able to see what the LER is as a by product of the test. i.e. the test should be about understanding your enlarger settings and what effect they have and not about finding numbers.

So in this case a certain level of detailed knowledge is useful, but only if you are having problems with your enlarger filtration settings in the first place.

LERs act as a guide. It's an easy way to calibrate the different color head settings. Their just like paper grades, except they have real meaning. Papers grade numbers are almost arbitrary. There is nothing in the standards about paper grades. Jones suggested the elimination of grades back in 1947, but the idea was too engrained with users that the manufacturers kept using them. If the OP wants to know the maximum "grade" from his color head, he could do a quick test and find the LER. He could test different papers. He could compare his resulting LERs with the LERs from another person's test to determine if his results are common or not. Question answered.

According to Annex A in ANSI/ISO 6846 - 1983, "The log exposure range of a photographic paper provides a useful, but not perfect, criterion for grading papers. It is useful because a satisfactory print is normally obtained when the log exposure range of a paper is matched to the effective density range of the negative image, provided that the scene and the scene lighting are normal. It is not a perfect criterion because papers with similar log exposure ranges will give prints that differ considerably in appearance if the shapes of the paper sensitometric curves are different. Moreover, a negative which prints well on a glossy paper (high Dmax) will print equally well on a matte paper coated with the same emulsion (low Dmax) even though their log exposure ranges will not be the same.

ISO range (R) which is determined directly from the log exposure range is, therefore, a useful guide for selecting a paper for a negative of known density scale. What is involved is the matching of the ISO range (R) with 100 times the effective density range of the negative image. For medium contrast papers, an exact match generally works best. For low contrast papers, the LER should be slightly less than the negative density range in most cases and conversely for high contrast papers. This means that to obtain the best prints from a single negative using two papers with differ in Dmax, it is necessary in most cases for the lower Dmax (lower contrast) paper to have a similar LER."

Comment: All the above is originally from Jones.

"It must also be remembered that optimum print quality depends on aesthetic factors which may indicate the use of a paper whose log exposure range differs considerably from the density range of the negative. Thus, the use of the ISO range/negative density range relationship is only approximate, as a starting point for critical work. The paper range required should be determined for each printed/enlarger, developer, and paper surface combination."

When I was consulting with Herb Ritts' production crew, I found they had three enlargers: two Ilford heads (I think) and a Durst. The printer had to set the Ilford heads at two different settings to obtain similar results and the Durst was adjusted accordingly. By doing a simple set of paper tests, the three enlargers could be calibrated so the printer could more easily work between the three. This was good since Ritts wouldn't show his client proofs, but gave them around 120 prints which his printer had to do in a single day.

LER is simply a useful tool in the toolbox.

whojammyflip · Sep 17, 2015

Indeed, for my purposes, my maximum "grade" from my enlarger would appear to be 3. It means I cannot get away with flat negatives, and trying to use Xtol which is a year old. I bumped my development time to 10 minutes and temperature to 21.5 deg C at the weekend with TMAX 400 and am still getting a CI of 0.50. Experiential learning is the best way of learning to do stuff, as I am finding out. The only thing I can think is my Xtol is 6 months old.

pentaxuser · Sep 17, 2015

hoojammyflip said:
It means I cannot get away with flat negatives, and trying to use Xtol which is a year old.

You must be guided by your experience and belief but is there good reason to believe that 1 year old Xtol has lost its potency?

I am using 25 month old Xtol stored in winebags and I cannot detect any difference from its potency at 6 months old

pentaxuser

whojammyflip · Sep 19, 2015

No idea, I am about to develop for 10 mins at 23C and have a look at what it looks like.

wiltw · Sep 19, 2015

Consulting an Ilford table, with different values to be dialed into color heads from different manufacturers, based upon the max densities which can be dialed in with your color head, this gives you an idea of what Grade you should be able to choose:

Sirius Glass · Sep 19, 2015

pentaxuser said:
hoojammyflip said:

It means I cannot get away with flat negatives, and trying to use Xtol which is a year old.

You must be guided by your experience and belief but is there good reason to believe that 1 year old Xtol has lost its potency?

I am using 25 month old Xtol stored in winebags and I cannot detect any difference from its potency at 6 months old

pentaxuser

Click to expand...

My experience with replenished XTOL.

Max grade from colour heads

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