Converting Split Grade times back into single grade?

Dr Croubie · Oct 6, 2014

I was Split-Grade printing the other day, on my LPL 6700 Colour Diffusion head, using Magenta/Yellow controls (not the MG filters), and for a certain neg on MGiv RC I was getting the best print with 3 seconds at 170Y, then another 3 seconds at 170M.

I was thinking about it a few days later, and the question is, is this not the same as printing a single-grade? Be it 3 seconds at 170M/170Y, or 6 seconds, or however many seconds at 0M/0Y (because Cyan doesn't count anyway), or some other convoluted formula involving times and filtration?
Whatever the method and formula, the question is, can this (or indeed any, this neg just turned out a nice even number) split-grade time be converted into a single-grade single-exposure? Or is there something special about split-grade that can't be replicated in a single exposure?

cowanw · Oct 6, 2014

Your example does not work however, with Zone vi variable heads as the stabilizer does not work on each light equally

Bill Burk · Oct 6, 2014

If you have a Stouffer scale step wedge, you could print it under the same split-grade setting. Then graph the result and from that, you could compare to similar graphs from a single grade paper (or filtered with single grade filter).

If you got the results you like, then the test might be "academic" but if you wanted to switch to Graded paper, it might be a necessary test to get you where you want to go.

If you did dodge and burn activity under one filter versus the other, then you took advantage of the split grade nature of printing, and it may be hard to replicate the result on a single grade.

ic-racer · Oct 6, 2014

Dr Croubie said:
I was Split-Grade printing the other day, on my LPL 6700 Colour Diffusion head, using Magenta/Yellow controls (not the MG filters), and for a certain neg on MGiv RC I was getting the best print with 3 seconds at 170Y, then another 3 seconds at 170M.

I was thinking about it a few days later, and the question is, is this not the same as printing a single-grade? Be it 3 seconds at 170M/170Y, or 6 seconds, or however many seconds at 0M/0Y (because Cyan doesn't count anyway), or some other convoluted formula involving times and filtration?
Whatever the method and formula, the question is, can this (or indeed any, this neg just turned out a nice even number) split-grade time be converted into a single-grade single-exposure? Or is there something special about split-grade that can't be replicated in a single exposure?

Just combine the filtration and add the times and do a single exposure. Nothing complicated about it.

Doremus Scudder · Oct 7, 2014

As mentioned, unless you did dodging and burning with only one of the filters, there is no difference at all between split printing and a single exposure.

However, converting your 170M + 170Y back to an intermediate filtration is not so easy. Even at the three seconds each, the "center" between M and Y will most likely not be anywhere close to 0M+0Y. You would have to calibrate.

If you want to make a print with just one exposure, you would be better off starting over and making test strips at different contrast grades.

FWIW, I use a base exposure of either xM or xY when printing VC and then change filtration for burning if needed. I rarely find the need to dodge under strong filtration at either end.

Best,

Doremus

David Brown · Oct 7, 2014

Doremus Scudder said:
However, converting your 170M + 170Y back to an intermediate filtration is not so easy.

Unless you have a StopClock Pro. It will do the conversion for you.

Even then, it's a good idea to do a test strip ...

MartinP · Oct 7, 2014

I think that the only way to be sure is to do some checks with your filters and your paper.

As well as small tolerance differences in the colour-head, there is the possibility of mechanical wear (or old bodged repairs/servicing) causing problems in the linkage between the dial and the dichroic-filter - plus the joys of different papers, from different manufacturers, actually having different behaviour across the mix of lighting affecting their blue and green sensitive emulsions.

Bob Carnie · Oct 7, 2014

I am not so sure about this single grade = split grade.

For example If one lays down a grade 1 exposure which enables all delicate highlights to record, but the shadows are a bit grey .
Then one puts a grade 5 exposure which only works on the shadow areas and creates the deep blacks one is trying to record.

This is two filter printing no dodge and burn has been done.
I do not think there is a single filter exposure that can mimic this....

Kind of like pre flashing then laying down a second higher hit to bring in the image contrast one wants..

In both cases a single filter may not work..

scheimfluger_77 · Oct 7, 2014

Bob Carnie said:
I am not so sure about this single grade = split grade.

For example If one lays down a grade 1 exposure which enables all delicate highlights to record, but the shadows are a bit grey .
Then one puts a grade 5 exposure which only works on the shadow areas and creates the deep blacks one is trying to record.

This is two filter printing no dodge and burn has been done.
I do not think there is a single filter exposure that can mimic this....

Kind of like pre flashing then laying down a second higher hit to bring in the image contrast one wants..

In both cases a single filter may not work..

This has not been my experience recently printing my pinhole negatives. These negatives are usually brighter in the center, requiring a higher contrast filter for the edges (usually) and a softer filter for the center. Nearly all of them require dodging and burning. I tried the two exposure thing with no manipulations and it doesn't work. perhaps the distribution of tones in my negatives makes this impossible, but it's hard to say. I'm getting some fairly good prints by the way.

ic-racer · Oct 7, 2014

The paper does not respond differently if it gets the blue and green together or in separate exposures.

In terms of a reverse conversion, if you have constructed a table like this then you can go backwards from your ISO(R) value and convert that to graded filter values.
Table shows my ISO(R) values from 0.45 to 1.60 for my various blue and green exposures (separate in time or overlapping, makes no difference).

Don't expect that table to work for you, as you don't know the light source color or exact filter colors or paper/developer combination used to make the chart.

cliveh · Oct 7, 2014

Dr Croubie said:
I was Split-Grade printing the other day, on my LPL 6700 Colour Diffusion head, using Magenta/Yellow controls (not the MG filters), and for a certain neg on MGiv RC I was getting the best print with 3 seconds at 170Y, then another 3 seconds at 170M.

I was thinking about it a few days later, and the question is, is this not the same as printing a single-grade? Be it 3 seconds at 170M/170Y, or 6 seconds, or however many seconds at 0M/0Y (because Cyan doesn't count anyway), or some other convoluted formula involving times and filtration?
Whatever the method and formula, the question is, can this (or indeed any, this neg just turned out a nice even number) split-grade time be converted into a single-grade single-exposure? Or is there something special about split-grade that can't be replicated in a single exposure?

If you are split grade printing on multigrade paper, you must be dodging and shading part/s of the print for a different M/Y contrast response and so it is not the same as a single exposure at whatever Y/M combination.

Bob Carnie · Oct 7, 2014

I agree with this premise but my point is that if you lay down softer tones with a lower filter , then add hard tones with the high filter.. a single exposure will not look the same in the print it will have less detail in the highlight region..

One only has to do this with a negative and a series of filters.. work from one end or the other it does not matter. low filter first or high filter first.

Its like using graded paper back in the 70's and 80's - one would either make their negatives to work with grade 3 papers or make the negs to work with grade 2 papers.. we would use softer and harder developers to try to split the difference...

If you have a single grade three print- and the highlights are burning out basically the only thing you can do is burn the crap out of the high range... we all remember the soft muddy grade 3 highlights?
But I can make the same looking grade three print with two filters - the difference will be that the highlights will come in naturally with the lower filter and the higher filter will create the contrast to match. without the need of burning in the highlights.

And if you want to burn in the highlights, you are much closer and add in a high filter burn to boot you not only have detail in the highlight region but you also have local contrast..

This is not possible with a single grade print , no matter how hard one tries

I do not use a 0 filter for this type of work as I do not like how the low end responds with Ilford Warmtone.

ic-racer said:
The paper does not respond differently if it gets the blue and green together or in separate exposures.

In terms of a reverse conversion, if you have constructed a table like this then you can go backwards from your ISO(R) value and convert that to graded filter values.
Table shows my ISO(R) values from 0.45 to 1.60 for my various blue and green exposures (separate in time or overlapping, makes no difference).
View attachment 95732

Don't expect that table to work for you, as you don't know the light source color or exact filter colors or paper/developer combination used to make the chart.

Bob Carnie · Oct 7, 2014

This is a very great way of controlling contrast locally by dodging during the base exposure.. as well burning back with a different filter.

cliveh said:
If you are split grade printing on multigrade paper, you must be dodging and shading part/s of the print for a different M/Y contrast response and so it is not the same as a single exposure at whatever Y/M combination.

MattKing · Oct 7, 2014

I think Bob Carnie is right in terms of practicality.

There are two reasons:

1) doing two exposures makes it easier to analyze separately the response of the paper to each of those exposures; and
2) the two different filtration settings are neither purely linear nor pure green or blue. It may or may not be possible to exactly duplicate the effect of the two exposures with one intermediate exposure.

It may, however, be possible to arrive at an intermediate exposure that is functionally so similar to the effect of the two exposures for the difference not to matter.

The first reason is the deciding one for me. I just wish I could combine it with Bob Carnie's "eye".

MartinP · Oct 7, 2014

One might suppose that, technically, two exposures (hard and soft, or any other) "should" be additive and give a result equivalent to the total amount of 'green' and 'blue' light used. But . . . whether a single intermediate filter from the multigrade filter set takes account of the overlap of the curves of the different emulsions, if made as separate exposures, is another question. I add that sentence because if Mr.Carnie is questioning the textbook answer there might be something in it (and I never thought to investigate the idea).

If I understand what he's suggesting, then the lowest intensity part of each of the exposure curves - at the level of a pre-flash exposure - when added together may produce a tone which would not be there with a single exposure through the "right" filter.

It sounds ignorant of me, but I've not really worried about a specific grade, only about adding or avoiding contrast by means of a couple of exposures (with different filters/colours) and some burning-in or whatever. Is it ever anyone's standard practice to make two exposures with no manipulations during them?

Edit: And a few simultaneous posts all agreeing(-ish) with each other !

MattKing · Oct 7, 2014

MartinP said:
Is it ever anyone's standard practice to make two exposures with no manipulations during them?

I aim for that when I print postcards for the APUG postcard exchange.

Some times you realize that you have a negative that doesn't require burning or dodging. If you come to that realization while using a split grade approach, there usually there is no real point to starting over with tests using a single, intermediate grade exposure.

That being said, if I am doing multiple prints (like in the postcard exchange) I may try to lighten my load by trying a single, intermediate grade exposure.

MartinP · Oct 7, 2014

And for postcard sizes you would have a very precise and very repetitive task, to be repeated many times for the exchange!

Thirty years ago (when I had to do this stuff all day) there were times when a tricky neg was required to be printed small, multiple times - for example, some advertising materials for shows used prints attached to brochures - so the solution was to make a larger, manipulated print then re-photograph it on 4x5 and then make 'straight' prints from the interneg. But that's a bit of thread diversion, sorry.

ic-racer · Oct 7, 2014

MattKing said:
I It may or may not be possible to exactly duplicate the effect of the two exposures with one intermediate exposure.

It may, however, be possible to arrive at an intermediate exposure that is functionally so similar to the effect of the two exposures for the difference not to matter.

Why throw away science? If there is no dodging or burning during the two separate exposures, then the effects are the same as if the two exposures occurred in overlapping time. This is basic photography 101.

Maris · Oct 7, 2014

The Emmerman process can add extra possibilities to split grade work. Here the paper is soaked in developer before exposure and then the "hard" exposure is given. This image is allowed to develop up and becomes a mask hiding unexposed silver halide under it. Then the "soft" exposure is given to add the highlights. Development and fix follows. This is a messy procedure with lots of variables. Wasting a day in the darkroom and lots of paper is possible.

DREW WILEY · Oct 7, 2014

There are all kinds of strategies and I think people often tend to overthink or overquantify them. Lots of the time I simply use the unfiltered "white" light (which is never truly white) of my various enlargers and print VC papers as if they were just an ordinary Grade 3 paper of days of
yore. Then as I start fine-tuning the print, I might tweak it with a little blue or M light (depending on the colorhead itself) for shadow punch, or
alternately with G or Y light to fill in highlight a bit. I don't see any sense in mixing B&G light or Y&M, as this simply created neutral density,
though on one of my enlargers I do have an Aristo coldlight which emits blue-green light simultaneously. I can go back and forth between my
additive and subtractive colorheads, and even this coldlight, and basically do the same thing. Then there are times when I feel true split printing does the best job extracting what I want from the neg. All of this is so much easier to do or demonstrate than to explain or quantify.
And different brands of paper, specific developers, image stain in the neg etc etc, are all factors which can make each specific instance a bit
different problem. Sometimes I deliberately develop the negs soft and print only using a deep blue filter. All kinds of tricks, and I suspect I can
do it as well as anyone; but the main point is that's it's all fun, and whatever works, works.

MattKing · Oct 7, 2014

ic-racer said:
Why throw away science? If there is no dodging or burning during the two separate exposures, then the effects are the same as if the two exposures occurred in overlapping time. This is basic photography 101.

I don't disagree about the theory. It is just that I find it more useful not to do the tests necessary to work out the exact practice.

Some of my reluctance is due to the temporary nature of my darkroom, my use of a (relatively small) number of papers, my use (sometimes) of borrowed darkrooms, and the relative ease of adapting to the variables by using a split grade process even when there are no manipulations.

Also, I kind of like the ease of obtaining 1/4 grade adjustments.

Bob Carnie · Oct 8, 2014

Drew.. have to disagree_**** I don't see any sense in mixing B&G light or Y&M, as this simply created neutral density,***

Not so - If you add a third component then you get neutral density... ie 10 cyan, 10 magenta 20 yellow.. you will have 10 units of ND or 1/3 stop with 10 yellow.

Magenta and Yellow filters are not equal and will darken or lighten a print differently.. with Magenta being the big Kahoona...

Bob Carnie · Oct 8, 2014

Maris

This sounds very messy... but quite different... what stops the process from being contaminated after the hard exposure ??? Is there a water stop process that slows down development , then back to the enlarger.

This would need pin registration on the easal I would think.

But I must say the first thing I was thinking reading your post is the locking down dmax and locking down dmin... this is exactly how I think when making prints... I never think about what filter I am using but I rather think about. Locking down the tonal regions with appropriate filters.

Bob

Maris said:
The Emmerman process can add extra possibilities to split grade work. Here the paper is soaked in developer before exposure and then the "hard" exposure is given. This image is allowed to develop up and becomes a mask hiding unexposed silver halide under it. Then the "soft" exposure is given to add the highlights. Development and fix follows. This is a messy procedure with lots of variables. Wasting a day in the darkroom and lots of paper is possible.

RalphLambrecht · Oct 8, 2014

Dr Croubie said:
I was Split-Grade printing the other day, on my LPL 6700 Colour Diffusion head, using Magenta/Yellow controls (not the MG filters), and for a certain neg on MGiv RC I was getting the best print with 3 seconds at 170Y, then another 3 seconds at 170M.

I was thinking about it a few days later, and the question is, is this not the same as printing a single-grade? Be it 3 seconds at 170M/170Y, or 6 seconds, or however many seconds at 0M/0Y (because Cyan doesn't count anyway), or some other convoluted formula involving times and filtration?
Whatever the method and formula, the question is, can this (or indeed any, this neg just turned out a nice even number) split-grade time be converted into a single-grade single-exposure? Or is there something special about split-grade that can't be replicated in a single exposure?

Other than dodging during the two exposures independently,there is nothing magic you couldn't do with a single exposure.

Maris · Oct 8, 2014

Bob Carnie said:
Maris

This sounds very messy... but quite different... what stops the process from being contaminated after the hard exposure ??? Is there a water stop process that slows down development , then back to the enlarger...
Bob

The paper, soaked in developer goes under the enlarger and stays there as a sequence of hard and soft exposures is applied. Exposures are spaced maybe 3 minutes apart so the result of one exposure develops to completion before the next exposure. Developed silver acts as an in situ mask influencing the effect of subsequent exposures. Exposures may be subdivided into shorter increments with development allowed to take place between "flashes". A piece of developer soaked photographic paper may spend 20 minutes under the enlarger getting various hard and soft exposures with pauses for development intervals. Then it's off to the fixer.

The last time I did this I wasted a day finding out that fibre based photographic paper changes size depending on how wet it is. The slightly out of register images I got might have been "art" but they weren't the subtle split grades I was looking for.

Converting Split Grade times back into single grade?

Dr Croubie

cowanw

Bill Burk

ic-racer

Doremus Scudder

David Brown

MartinP

Bob Carnie

scheimfluger_77

ic-racer

cliveh

Bob Carnie

Bob Carnie

MattKing

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MartinP

MattKing

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ic-racer

Maris

DREW WILEY

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Bob Carnie

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Maris

Converting Split Grade times back into single grade?

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