splitgrade vs. single filter

Roger Hicks · Oct 31, 2006

jstraw said:
Can anyone shed any light on the origins of split-grade printing? When did it first appear in the literature?

Early 90s. My wife Frances Schultz 'discovered' the technique; discussed it with experts at Ilford (including the legendary Mike Gristwood); and found that several other people had already 'discovered' the same idea at around the same time, with varying degrees of theoretical justification behind why they did it.

Of course it was inherent in the Multigrade principle, first patented by Ilford in about 1939. An American paper -- Defender? -- was first to market, using Ilford dyes, because at the time the UK was having problems with Agfa's biggest customer; the US declined to join in with this dispute at first. Ilford let the American company have the dyes because of personal links between their research scientists. At the time, there was no competition issue because Ilford didn't export to the US.

Cheers,

R. (www.rogerandfrances.com -- the same Frances)

JBrunner · Oct 31, 2006

Gordon Hutchings touches on it briefly in The Book of Pyro, under the heading, Printing Procedures. As I have the second printing (1992) I do not know if the information is in the earlier printing. Anyone?

lee · Oct 31, 2006

JBrunner said:
Gordon Hutchings touches on it briefly in The Book of Pyro, under the heading, Printing Procedures. As I have the second printing (1992) I do not know if the information is in the earlier printing. Anyone?

I first became aware of split filter printing sometime around the early 1990's. A friend bought a Zone VI enlarger with the two color head and Fred Picker had written some instructions on using the two color head. Fred recommended laying down the blue layer first but I have moved my printing to laying down the green first. It doesn't matter because photons are photons are photons.

lee\c

Roger Hicks · Oct 31, 2006

lee said:
It doesn't matter because photons are photons are photons.

lee\c

Or to quote Mike Gristwood, "The paper is refreshingly ignorant of what you are printing on it."

Cheers,

R.

Nick Zentena · Oct 31, 2006

I think the big advantage of split filtering is it's visual. You see what looks best and go from there.

frugal · Nov 1, 2006

Roger Hicks said:
The important thing to remember is that while there is always a single filter grade that will give the identical result for an undodged/unburned negative, split printing will allow you to burn different areas at different contrast grades. Also, some people find split-grade more intuitive.

There is however no merit in the idea that you can expose the highlights at one grade and the shadows at another unless you dodge or burn differentially during the two exposures.

Cheers,

Roger (www.rogerandfrances.com)

Yes, but my understanding is that split grade can give you a grade that you tend to not have any other way, like 3.82 or something like that. Now if you're using a dichroic head and dialing in the contrast you can probably get the same grade but if you're using the range of 00, 0, 1, 1.5, 2, etc filters you probably can't.

I'll admit that I haven't had a chance to try it myself as I've just been reading up on it recently (in Les' book) and haven't had darkroom access to try it yet. But I can see how for some people it's more intuitive because you focus on the highlights and the shadows separately whereas I've seen a lot of people have problems with single-grade printing in differentiating between when they need to change the density and when they need to change the contrast.

Roger Hicks · Nov 1, 2006

frugal said:
Yes, but my understanding is that split grade can give you a grade that you tend to not have any other way, like 3.82 or something like that. Now if you're using a dichroic head and dialing in the contrast you can probably get the same grade but if you're using the range of 00, 0, 1, 1.5, 2, etc filters you probably can't.

I tend to forget this because we use dedicated multicontrast heads where you dial the contrast straight in (we use Meograde but there are many others). Unless you do this, or use a colour head, you are right: you have to split the exposure to get anything other than half-grades. Well, that or use two different developers (high and low contrast) which is even more hassle.

Cheers,

Roger

jstraw · Nov 1, 2006

Roger Hicks said:
The important thing to remember is that while there is always a single filter grade that will give the identical result for an undodged/unburned negative...

This seems counterintuitive to me. Is this really so?

srs5694 · Nov 1, 2006

jstraw said:
Roger Hicks said:

The important thing to remember is that while there is always a single filter grade that will give the identical result for an undodged/unburned negative...

Click to expand...

This seems counterintuitive to me. Is this really so?

Think of it this way: In split-grade printing, you're using filters to restrict the light to nothing but yellow light (green plus red) for an exposure of a certain length of time and then to nothing but magenta light (blue plus red) for an exposure of another length of time. The paper is insensitive to red light, so we can ignore that, leaving the only light of interest to green light followed by blue light (or the other way around). This translates to just a certain number of green and blue photons. That same number of photons can be passed, and in the same green/blue proportions, by a single exposure that blocks the appropriate amount of green and/or blue light, via use of appropriate filters.

That said, this analysis employs a number of simplifying assumptions, such as ignoring reciprocity characteristics, the use of "perfect" filters, etc. That said, I don't know of any theoretical reason why the analysis is wrong, although I'm certainly open to the possibility that there are some very subtle effects of split-grade printing that would be difficult or impossible to reproduce with a single exposure. (Roger's already mentioned the ability to dodge/burn each exposure independently; IMHO, that's another matter.) At the very least, though, the basics work out the same in both split-grade and conventional printing: You expose the paper to varying amounts of blue and green light to control the contrast.

jstraw · Nov 1, 2006

srs5694 said:
Think of it this way: In split-grade printing, you're using filters to restrict the light to nothing but yellow light (green plus red) for an exposure of a certain length of time and then to nothing but magenta light (blue plus red) for an exposure of another length of time. The paper is insensitive to red light, so we can ignore that, leaving the only light of interest to green light followed by blue light (or the other way around). This translates to just a certain number of green and blue photons. That same number of photons can be passed, and in the same green/blue proportions, by a single exposure that blocks the appropriate amount of green and/or blue light, via use of appropriate filters.

That said, this analysis employs a number of simplifying assumptions, such as ignoring reciprocity characteristics, the use of "perfect" filters, etc. That said, I don't know of any theoretical reason why the analysis is wrong, although I'm certainly open to the possibility that there are some very subtle effects of split-grade printing that would be difficult or impossible to reproduce with a single exposure. (Roger's already mentioned the ability to dodge/burn each exposure independently; IMHO, that's another matter.) At the very least, though, the basics work out the same in both split-grade and conventional printing: You expose the paper to varying amounts of blue and green light to control the contrast.

Thanks for an excellent explanation. I guess the problem with duplicating the results of split-grade printing without splitting grades would be determining the exact filtration. That would be a complex undertaking and with split-grade, it's unnecessary. Would you concur?

Roger Hicks · Nov 2, 2006

jstraw said:
This seems counterintuitive to me. Is this really so?

Yes, it's counterintuitive as hell. I took some persuading, but Mike Gristwood (who was Ilford's leading tech support man until the bankruptcy) demonstrated entirely to my satisfaction that it is so. The post immediately after yours explains why very well, though in a different way from the approach Mike chose (he drew two response curves).

Personally, I find single-filter printing easier, possibly because we use the Meograde heads: we can look at a work print and say, "Needs about 1/4 grade more contrast," and dial it in. Of course, if needed, we also dial in different contrast grades for dodging and burning.

Cheers,

R.

anyhuus · Dec 15, 2006

I have now tried split-grade printing with success

Hi all.

In this thread lots of you have given really comprehensive answers and information around split-grade printing. When I started the thread, it turned out that I had asked "the wrong question" (how to calcualte single grade filtering from split-grade times). Based on overwhelming respons on the subject of split-grade printing, I decided to dig into available info sources and try to get the grip on this. In the darkroom yesterday I think I had a breakthrough in understanding. At least it felt that way, as I made a quantum leap in controling the resulting print. Not only because of the methodical separation of exposure and contrast that split-grade printing provides, but the real revelation in controlling local contrast by dodging and burning soft- and hard-exposures separately.

I am not in any way thinking that I have reached the end of the journey of learning this - I have merely started on it. But the sense of control was a first-time yesterday. Thank you all for pointing out the direction for me.

Now new questions arise. What I find difficult is when testing for the soft-exposure, to evaluate the test-strip. The credo when doing soft first, is to evaluate only the highligts, and disregard the shadows at that time. I find it difficult to evaluate highlights only. Is there any practical way or "tricks of the trade" to do this? I haven't tried hard exposure first yet, but is that perhaps easier?

The second question is how do one combine split-grade printing and f-stop printing?. When evaluating a print, and perhaps decide to edge burn 1/2 stop. In single grade printing it is a simple question of adjusting a single exposure time. How do you do it when you have split-grade exposures? An edge might contain a full tonal scale, thus needing burning on both exposures?

Donald Miller · Dec 15, 2006

jstraw said:
That would be a complex undertaking and with split-grade, it's unnecessary. Would you concur?

It is no more complex than split grade printing...in fact in some cases split grade printing is the more complex. I can arrive at very near the appropriate exposure and filter with a single 1 inch strip of paper layed across the projected image. There is no way that can be done with split grade printing.

Will S · Dec 15, 2006

anyhuus said:
Now new questions arise. What I find difficult is when testing for the soft-exposure, to evaluate the test-strip. The credo when doing soft first, is to evaluate only the highligts, and disregard the shadows at that time. I find it difficult to evaluate highlights only. Is there any practical way or "tricks of the trade" to do this? I haven't tried hard exposure first yet, but is that perhaps easier?

I'm no expert, but to quote Les McClean, "a little soft goes a long way" So, I pick the time that it first looks good and maybe back up 1/12th or 1/6th and then try that. If it still looks like the highlights are too dark, then I back it up two more and try that. If that is then blownout, I know where I should be.

anyhuus said:
The second question is how do one combine split-grade printing and f-stop printing?. When evaluating a print, and perhaps decide to edge burn 1/2 stop. In single grade printing it is a simple question of adjusting a single exposure time. How do you do it when you have split-grade exposures? An edge might contain a full tonal scale, thus needing burning on both exposures?

I always burn in on grade 0 if I am burning in highlights. And, I can't think what else I ever burn in. I don't think you can accurately think of "1/2 a stop" for both grades. Instead I think "1/2 a stop on grade 0" If there are details in the burn area that need to be more contrasty by all means I use Grade 5 to burn, but it is pretty much always Grade 0 since the grade 5 can really make those little details look very contrasty, which I don't like. In the scenario you describe I suppose I would burn on both grade 0 for 1/2 stop and grade 5, but I bet it would come out just fine on grade 0 alone.

Good luck,

Will

Craig · Dec 15, 2006

anyhuus;406084 Now new questions arise. What I find difficult is when testing for the soft-exposure said:
When I took Les's course, he told us to pick the area in the brightest highlight of the print that we want detail to show. When doing the soft test strip you want the exposure where detail in that highlight is just starting to show. In other words, where you're starting to get tone just off paper base white. That's the correct exposure for the soft, then procede to esthablish the hard exposure.

jstraw · Dec 15, 2006

The really tricky part is managing a test strip so that you can see a variety of times for that highlight area if it's small. This is an inherent problem with incremental test-strips with or with out f-stop timing and with or without split-grade.

My approach for a small highlight area has been to forget the usual test strip and do a series of small test prints of just that highlight area, at my preferred f-stop times. I use several, separate, small pieces of paper and use them all on that same highlight area one by one, at the various timings then develop them all together.

lee · Dec 15, 2006

why not use a 1/2 a sheet of paper or a whole sheet of paper? that way you can see the whole print.

lee\c

jstraw · Dec 15, 2006

lee said:
why not use a 1/2 a sheet of paper or a whole sheet of paper? that way you can see the whole print.

lee\c

Because I'm a cheap b*stard.

Once I get the soft exposure I think will be correct, I do a full sheet with that exposure to be sure, then expose another full sheet at that exposure as a base exposure for a test strip for the hard filter the traditional way.

Let's say my little test prints tell me that the area I was concerned with need a 16 second exposure. I then expose a whole sheet with the soft filter for 16 seconds and then change filters and do a 2/2.8/4/5.6/8/11/16/22/32 second test.

Occasionally I will have the same issue for a shadow area that's so localized that I so the same set of small test prints for the same spot.

Please keep in mind that I'm very new to split-grade printing.

lee · Dec 15, 2006

"Please keep in mind that I'm very new to split-grade printing."

I understand you are new to split grade printing and that makes it all the more important not to cheapen the process. When you are learning something you should follow the proper technique and then after you have some skill then you can deviate from the tried and true methods. After you make the full sheet of soft exposure if I were looking to save paper, I would go ahead and make the hard test on top of the soft sheet of paper. Instead of just making a full sheet of soft light. Sorry for the clumsy wording.

There is a learning curve that must be over come. Split grade printing is not a hard technique to master but it does require some learned judgment. Keep on keeping on and it will become second nature.

lee\c

jstraw · Dec 15, 2006

lee said:
After you make the full sheet of soft exposure if I were looking to save paper, I would go ahead and make the hard test on top of the soft sheet of paper. Instead of just making a full sheet of soft light.

The clumsy wording is mine, Lee. That's what I do. In fact, I do both. I make a full sheet of the soft exposure first, to ensure that I like what I thought I liked, *then* I make a hard exposure test on top of that base, soft exposure on the next sheet of paper.

Not to cast the estimable Les McLean in a bad light...after all, I owe him plenty...but in his tutorial he bases his decision for a 14 second soft exposure on this test strip:

The fact that there is no information in that image about what that highlight on the handle would look like at 16, 18 or 20 seconds illustrates why I identify the area of highlight relevance and do a series of test exposures for *that spot*.

An alternative to my current procedure, which I am considering, is to make a special easel that would allow me to move the paper under enlarger so that I can expose a series of strips on a single sheet of paper to the same area of the enlargement.

Bob F. · Dec 15, 2006

This thread prompted me to do something I have been meaning to do for a while... I just finished hacking my Dust AC1200 to switch the yellow and magenta filters fully in individually. The AC1200 has two sets of filters: one normal manual set with knobs you twiddle and another set controlled by electric solenoids which it uses for colour paper exposures. In B&W use they are normally used as a shutter: either fully in or fully out.

By controlling the solenoids with a switch I no longer need to twiddle the filter knobs up/down for each exposure (with the attendant fear of nudging the head off focus) - just turn the switch to Y or M (the switch has a 3rd position that restores original operation). Yay!

Cheers, Bob.

Lee L · Dec 15, 2006

"Way Beyond Monochrome" by Lambrecht and Woodhouse has plans for such an easel that you might want to look at for ideas. Ralph Lambrecht is here at APUG.

Lee

Les McLean · Dec 15, 2006

Sorry to contradict you but the fact is there is lots of highlight information in the 14 second exposure, otherwise I would not have used it. Look at the difference between the tone of the 14 and 12 second exposure. Will S made the point earlier in the thread that when I teach split grade printing I say "a little soft filtration goes a long way" and it does. If I had used your choice of 16,18 or 20 seconds the highlights would be progressively muddier with each increase in soft exposure and the print would have no sparkle.

I use the soft filtration exposure simply to put very delicate tonality into the highlights, the contrast is achieved when the hard filtration exposure is given and the detail in the highlights comes with the contrast. This is known as local or micro contrast.

Ask Lee what the final print of this image looks like and he will assure you that there is detail throughout both highlights and shadows.

jstraw said:
The clumsy wording is mine, Lee. That's what I do. In fact, I do both. I make a full sheet of the soft exposure first, to ensure that I like what I thought I liked, *then* I make a hard exposure test on top of that base, soft exposure on the next sheet of paper.

Not to cast the estimable Les McLean in a bad light...after all, I owe him plenty...but in his tutorial he bases his decision for a 14 second soft exposure on this test strip:

The fact that there is no information in that image about what that highlight on the handle would look like at 16, 18 or 20 seconds illustrates why I identify the area of highlight relevance and do a series of test exposures for *that spot*.

An alternative to my current procedure, which I am considering, is to make a special easel that would allow me to move the paper under enlarger so that I can expose a series of strips on a single sheet of paper to the same area of the enlargement.

lee · Dec 15, 2006

jstraw said:
The clumsy wording is mine, Lee. That's what I do. In fact, I do both. I make a full sheet of the soft exposure first, to ensure that I like what I thought I liked, *then* I make a hard exposure test on top of that base, soft exposure on the next sheet of paper.

Not to cast the estimable Les McLean in a bad light...after all, I owe him plenty...but in his tutorial he bases his decision for a 14 second soft exposure on this test strip:

The fact that there is no information in that image about what that highlight on the handle would look like at 16, 18 or 20 seconds illustrates why I identify the area of highlight relevance and do a series of test exposures for *that spot*.

An alternative to my current procedure, which I am considering, is to make a special easel that would allow me to move the paper under enlarger so that I can expose a series of strips on a single sheet of paper to the same area of the enlargement.

I actually own that print he uses for his example. I got it in a print exchange a year or so ago. I am sure that he knew exactly what that highlite was to look like when he started his process. I have watched Les enough in the several workshops we have done in the field and in my darkroom that he is in full control of what he wants the print to look like at the beginning and then it is just a matter of time until his print bows to his wishes.

Like the fellow who asked the musician on the street one day "How do you get to Carnegie Hall" to which the musician said, "Practice, man, Practice."

lee\c

jstraw · Dec 15, 2006

Les McLean said:
Sorry to contradict you but the fact is there is lots of highlight information in the 14 second exposure, otherwise I would not have used it. Look at the difference between the tone of the 14 and 12 second exposure. Will S made the point earlier in the thread that when I teach split grade printing I say "a little soft filtration goes a long way" and it does. If I had used your choice of 16,18 or 20 seconds the highlights would be progressively muddier with each increase in soft exposure and the print would have no sparkle.

I use the soft filtration exposure simply to put very delicate tonality into the highlights, the contrast is achieved when the hard filtration exposure is given and the detail in the highlights comes with the contrast. This is known as local or micro contrast.

Ask Lee what the final print of this image looks like and he will assure you that there is detail throughout both highlights and shadows.

I feel compelled to observe that you're not contradicting me, though you may have misread me. I didn't say anything about the quantity of information contained in the 14 second exposure. I merely observed that the test strip gives no information about what that area of the handle would look like with an exposure exceeding 14 seconds. I also said nothing about making a choice for 16, 18 or 20 seconds.

The fact is, if the purpose of the test strip was to determine a soft exposure for the highlights on the handle, the test strip *ends* at 14 seconds and effectively, there is no test for a longer exposure. I'm not arguing that 14 seconds is not the right exposure. You're an experienced printer and recognized that 14 seconds gave that area the tonality that you were looking for and you didn't need to see that area with too much exposure in order to know it would *be* too much exposure. I'm new at this and it's useful to me to see a range from too little to too much. I'm just saying that the test strip doesn't tell you anything about the appearance of that area for longer exposures.

I pointed this out only to illustrate my thinking about needing to see the exposure options for the same, local highlight and that once a test strip is dealing with a different area of the enlargement, that's not what one gets.

splitgrade vs. single filter

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