Single grade FB papers

[Roger Cole]

That doesn't really show anything though. The point would be to make a print using filters (not unfiltered) and then split grade, and try your best to make them as close to identical as possible. Just making one without a filter (they may call it grade 2 but that doesn't mean it's the same as a grade 2 filter and certainly doesn't mean it's the same as any particular combination of hard and soft filter split printing) and a split grade the way you like is... it's not even apples to oranges, even if you do match some arbitrary midtone. It's apples to chicken or something.

It's clearly softer. The only semi-meaningful comparison would be to try 2.5, 3 etc. grade filters and match as close as you can across all the tones. Even then, with filters, you might well end up with a situation where, say, a grade 3 is just a bit more contrasty than the split grade while 2.5 is a bit less, while with a continuously variable VC or colorhead you could easily match an effective grade 2.85 or whatever.

This seems more a near religious belief than anything empirical so I'm bowing out. The vast majority of us do this for fun and self expression. We can and should do it however pleases us most.

 

[Craig]

Thanks Craig!

The second print is unfiltered, right?

That's right.

 

[Craig]

(they may call it grade 2 but that doesn't mean it's the same as a grade 2 filter

The ilford tech sheet says otherwise. According to it, unfiltered and a grade 2 multigrade filter are identical.

 

[Craig]

Indeed. There's nothing self-masking about VC papers, regardless if they're used for split grade or single-grade printing. That part of Craig's post just doesn't add up. There's no difference between a split-grade print or a single exposure at the same effective grade, unless burning & dodging are used.

It's not the paper that is the mask, it's the neg. Here is part of Les's explanation: https://www.photrio.com/forum/threads/split-grade-printing.813/post-11340

The density of the highlight areas of the negative act as a mask to protect the areas of soft exposure when exposing in the hard (shadow) areas, such that highlight (soft) exposure is not affected by the hard exposure.

 

[koraks]

Craig, with all due respect, and I mean no harm in the following, but that explanation doesn't jive with me. Calling the negative its own compensation mask is tautological - of course the dense areas in the negative prevent an image being formed on the high contrast emulsion unless a lot of (over)exposure is given on the blue/magenta spectrum. In the post you link to, Les explains how he likes to create punchy negatives for split grade printing, but this doesn't mean that split grade printing (without any burning & dodging) will get a result that's different from a straight single grade print.

Your experiment, while interesting, is IMO not a good illustration of the point you're trying to make because it relies on two assumptions that you'd have to validate first: (1) that the effective grade you arrived at in the split grade print confirms in reality with the theoretical approximation you arrived at through the low/high contrast exposure ratio, and (2) that the paper will indeed hit exactly grade 2 with unfiltered exposure. In reality, these assumptions may very well be off a bit, and that will skew the results. In particular, I suspect your split-grade print was effectively of a higher grade than the white light print, and that explains all the difference between these two prints, and not the fact that one print was exposed only once, and the other one was exposed twice.

A better experiment would be to print some step wedges with a split-grade approach and using a single exposure, and then determine which split grade ratio will produce the exact same grades as the single exposures. Then print a negative with a single exposure and the matching split grade exposure. The result will be two identical prints.
Fortunately, someone has already done the legwork for us: https://www.photrio.com/forum/threads/understanding-split-grade-printing.178409/post-2587061
As you can see there, @jonmon6691 demonstrated that two consecutive exposures at grade 0 and grade 5 (i.e. split grade) produces the same densities as a matching single grade exposure.

Again, the value of split grade lies in:
1: An intuitive way of working, at least 'once you get the hang of it'. But it's fairly easy to get this down and this advantage should not be underestimated.
2: A fairly quick way to dial in the desired contrast grade. A minor drawback is that you generally don't really know what effective grade that is, but frankly, who cares if the print comes out well?
3: Most importantly, the ability to burn & dodge during both exposures, which give creative control that's virtually impossible to achieve in a single grade exposure.
All this makes split grade printing a perfectly viable approach.

What the story about Les McNeal demonstrates, at least for me, is that a printer can achieve at a very effective workflow and make great prints without actually understanding very well at a theoretical level what's happening in the materials they're using. That's not a mean jab at Les' intellect - far from it. It's a simple observation about how most artists work, and perhaps one of the reasons THAT they work: they're not sidetracked by digging deeper and deeper into technique, but instead figure out something that works and then just use it to their advantage. There's nothing, absolutely nothing, wrong with that!

 

[snusmumriken]

It's not the paper that is the mask, it's the neg. Here is part of Les's explanation: https://www.photrio.com/forum/threads/split-grade-printing.813/post-11340

The density of the highlight areas of the negative act as a mask to protect the areas of soft exposure when exposing in the hard (shadow) areas, such that highlight (soft) exposure is not affected by the hard exposure.

Craig, congratulations and thanks for bringing some actual evidence to the discussion. I would willingly follow suit, but am physically unable to use my darkroom just now, so it will be a few weeks hence.

Like @koraks, I don’t believe the masking effect of dense highlights in the negative explains anything. That effect must be the same whether the yellow exposure is given at the same time as the magenta one, or at a different time. So I’m sure it applies to split-grade and single-exposure printing equally.

My (regrettably common!) experience of making prints on Ilford MG while forgetting to insert a filter is that the result is actually closer to grade 2 1/2 than 2. That makes me doubt that your split-grade print is only grade 1.6, and I suspect that your estimates of the contrast grades chiefly reflect different ways of inferring what contrast grade you have applied.

The real question is whether your split-grade print could be matched with a single exposure. Studying the two leaves me feeling that I could have made the unfiltered one match the split-grade one by using a tad less exposure and a tad more contrast. I really wish I could just go into the darkroom today and put this to the test. As said, I really appreciate your own willingness to offer evidence rather than just opinion.

I do accept that using split-grade methods with dodging and burning you could achieve heightened local contrast in the vegetation and engine mechanism, but I am unpersuaded that the basic print is any different.

 

[Bill Burk]

Ok this makes perfect sense to me.

Self-masking for the high contrast exposure.

It’s like someone painted your negative with opaque. That kind of mask.

As long as you keep the high contrast layer under its threshold in the area of the negative with high density (like blocked skies), there will not be any detail in the print contributed by the high contrast layer.

Then you can expose for as long as it takes in the low contrast filter and the high contrast layer won’t reach its threshold.

But the low contrast layer can build billowy clouds. You would want to dodge the main part of the picture when you burn in the skies.

Is that what you do?

 

[Craig]

Ok this makes perfect sense to me.

Self-masking for the high contrast exposure.

It’s like someone painted your negative with opaque. That kind of mask.

As long as you keep the high contrast layer under its threshold in the area of the negative with high density (like blocked skies), there will not be any detail in the print contributed by the high contrast layer.

Then you can expose for as long as it takes in the low contrast filter and the high contrast layer won’t reach its threshold.

But the low contrast layer can build billowy clouds. You would want to dodge the main part of the picture when you burn in the skies.

Is that what you do?

In practice, that's exactly how it works for me. I expose the low contrast first, then the high contrast. I find the highlight values laid down under the low contrast filter are affected very little by the high contrast filter. There isn't much difference in the highlight value test strip with the low contrast filter only and the final exposure with the high contrast added afterwards. The process greatly reduces the need for dodging and burning, as the negative sort of does it itself.

I have found that I do get a different look than if I had made a single exposure under a single filter. I think it probably is like Les theorized about microcontrast, I have certainly seen the effect, whatever it's cause.

Koraks, I'll disagree a bit about the interpretation of the curves you linked to. If we were printing step tablets, I'd agree, that the overall tones of a single exposure and a split grade should arrive at the same place. However, a typical photograph is far from a single panel of continuous tone, so the interaction of the range of tones in a scene and how each responds in different parts of the image can create a different effect than a single exposure can. Some parts of the image will react to the #5 filter differently than others, and the same with a #0. That is where Les talked about the global contrast of the image is different than the microcontrast at specific locations within the image.

I ran out of time yesterday to attempt to match the global contrast of my two prints, but I have done that previously, and for lack of a better word the split print had more "sparkle".

A big advantage I have found is that I can arrive at a pleasing print much faster and with less waste than I can with a single exposure, that is valuable to me. I have never been able to perfect burning in around complicated shapes, such as if I was to burn in the sky above the locomotive. I have not had it look like it wasn't burnt in, rather than having it look natural and a single exposure. I can achieve a natural looking print much easier with split grade. I don't know the science behind it, but I know it works.

Perhaps the best thing is try it for yourself and see what you can do. Then you have actual prints to evaluate, rather than inages undoubtly processed by a scanner and affected by monitor calibration etc.

 

[Doremus Scudder]

The ilford tech sheet says otherwise. According to it, unfiltered and a grade 2 multigrade filter are identical.

This depends entirely on the color temperature of your light source and the proportion of blue vs green components. Sure, most tungsten halogen light sources will render somewhere close to a grade 2 print when used unfiltered, but the variation in that from bulb to bulb might easily be a grade in either direction. Use the #2 filter and compare that to an unfiltered print where a given density matches and see.

It's not the paper that is the mask, it's the neg. Here is part of Les's explanation: https://www.photrio.com/forum/threads/split-grade-printing.813/post-11340

The density of the highlight areas of the negative act as a mask to protect the areas of soft exposure when exposing in the hard (shadow) areas, such that highlight (soft) exposure is not affected by the hard exposure.

I don't buy Les' explanation. Why in the world would a high-density area in the negative mask blue light more than green? It's not like it's acting as a color filter or anything (with the possible exception of negatives developed in staining developers). And, even if there were a masking effect that was wavelength dependent, why would that only work when you give two separate, filtered exposures and not when both wavelengths were present at once? It just doesn't make sense. The laws of physics work whether the blue light exposure is given separately or together with the green.

To repeat: the paper doesn't care if it gets the blue and green light exposures separately or together. How could it?

Ok this makes perfect sense to me.

Self-masking for the high contrast exposure.

It’s like someone painted your negative with opaque. That kind of mask.

As long as you keep the high contrast layer under its threshold in the area of the negative with high density (like blocked skies), there will not be any detail in the print contributed by the high contrast layer.

Then you can expose for as long as it takes in the low contrast filter and the high contrast layer won’t reach its threshold.

But the low contrast layer can build billowy clouds. You would want to dodge the main part of the picture when you burn in the skies.

Is that what you do?

Yes, the high-density areas of a negative will keep the blue-light exposure from reaching threshold exposure, assuming the exposure time is short enough that not enough blue light makes it to the emulsion. That should happen whether or not there were green light passing through the negative at the same time. How can varying the proportion of blue to green in a single exposure be different than giving the same proportion of blue to green in two separate exposures.

The only possible explanation that I can think of for a difference is that intermediate wavelengths between the extremes of blue and green have an effect on the paper's contrast response that isn't there when only using pure blue and pure green. I find that hard to believe, however, since the color-sensitive elements in the emulsion would have to be, in essence, a separate cyan-sensitive component that doesn't get exposed when using split-grade techniques that does get exposed when using single-filtration. If this were, indeed, the case, then a single exposure using only discrete green and blue wavelengths, as in an RGB color head or using well-filtered green and blue LEDs, would yield different results than exposing using a halogen bulb and Ilford's MG filters. Has anyone experienced this?

I don't seem to be able to find the spectral response curves for the individual components in VC papers anywhere easily. Anyone out there have them?

Doremus

 

[Craig]

I don't seem to be able to find the spectral response curves for the individual components in VC papers anywhere easily. Anyone out there have them?

Doremus

https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Contrast-control-for-Ilford-Multigrade.pdf

 

[Doremus Scudder]

https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Contrast-control-for-Ilford-Multigrade.pdf

This doesn't show what I'm referring to. What's needed is the spectral response of each of the three color-sensitive components of the emulsion with bandwidth and peaks for each. We need to see if there is any overlap in sensitivities and how that might affect the final outcome when the negative is exposed to a continuous-spectrum source, like tungsten light, in which there would be intermediate wavelengths between whatever wavelength we choose to name blue and that we choose to name green.

Ilford also doesn't define what they call blue or green, nor how narrow or wide (or even overlapping) the bandwidths for those colors are.

Obviously, there is quite a bit of overlap in the spectral sensitivity of the three components, since all three react to both blue and green. The real question is, is there a difference when using just "extreme blue" and "extreme green" when compared to using an exposure that contains intermediate wavelengths. Only if this makes a real difference would there be a potential advantage to split-grade printing for the base exposure over a single, intermediately-filtered exposure.

Doremus

 

[Craig]

The real question is, is there a difference when using just "extreme blue" and "extreme green" when compared to using an exposure that contains intermediate wavelengths.

My experiences is this is the case. Try it for yourself and see what you get.

 

[snusmumriken]

The only possible explanation that I can think of for a difference is that intermediate wavelengths between the extremes of blue and green have an effect on the paper's contrast response that isn't there when only using pure blue and pure green.

I don’t know how all colour heads work, but surely nothing that relies on filters is going to produce ‘pure’ blue or ‘pure’ green? Same with under-lens filter kits - yet split grade techniques are practised with those.

 

[Patrick Robert James]

I think at this point I've pretty much printed about every which way one can print a photograph. I've used various light sources, blue/green, magenta/yellow, dichroic CMY heads, VCCE heads, single filters; various enlarger types, condenser, diffusion, hybrids, blah blah blah.

Split printing is the easiest way to arrive at an acceptable result. I've printed that way for the most part since the 90s regardless of the enlarger/light source. Last year I picked up a Zonemaster meter from RHDesigns because I was tired of test strips. I don't want to see another one the rest of my life. Lol. Now I just use the Zonemaster to place tones which gives me a contrast grade to start. I now print the exact way Doremus described earlier in this thread. In other words, you have two experienced printers arriving at the same conclusions independent of one another even though they produce different work. That says a lot I think.

The ultimate test for everyone though is if you are satisfied with your prints then you are doing ok.

 

[Patrick Robert James]

I don’t know how all colour heads work, but surely nothing that relies on filters is going to produce ‘pure’ blue or ‘pure’ green? Same with under-lens filter kits - yet split grade techniques are practised with those.

I've printed with pure blue and pure green filters quite a lot. I use a Blue 47b and a Green 58. Same difference really except it is very difficult to see the blue exposure due to the way our eyes work. Magenta and yellow add red to the blue and green which makes seeing the image on the easel far easier, though the red light does nothing. In essence Blue and Green are cut filters. they only allow those wavelengths through.

Back in the day I think it was Oriental that advised using a Blue 47 to get more contrast out of their paper vs. using the Ilford #5 filter. That could have been something unique to Oriental or it might have worked with other papers too. I never bothered to find out. If I know I need the max contrast I use a blue filter. Does it make a difference? To be honest I don't know because I can't be bothered to test it.

I've often though over the years of using blue/cyan/green filters (or even more finely cut filters) to really fine tune contrast and tone, but without the exact technical details from Ilford or whoever in regards to the exact sensitivity of the different emulsion layers, I don't see a point to pursuing it. I don't really think it would make a damn bit of difference really. Life is short and getting shorter and my prints are good enough....

 

[Pieter12]

I don’t know how all colour heads work, but surely nothing that relies on filters is going to produce ‘pure’ blue or ‘pure’ green? Same with under-lens filter kits - yet split grade techniques are practised with those.

LED heads should be able to produce narrow wavelengths eliminating too much contamination. https://heilandelectronic.de/files/Heiland_Enlarger_Head_Report.pdf

 

[Doremus Scudder]

Both LED heads that have blue and green sharp-cut LEDs and RGB heads that rely on red, blue and green sharp-cut light sources (tubes or filtered bulbs or whatever) can produce a really limited wavelength blue and green. Using the #47 and #58 filters does the same. Even the most extreme MG filters will do much the same. A deep magenta filter passes only blue and red; green is almost entirely eliminated. Similarly, a deep yellow filter passes only red and green; blue being eliminated. It's the filters in between, like #1, 2, 3 MG filters or partial filtration with dichroic heads that mix both blue and green together in a broader spectrum that is more continuous.

FWIW, I get a contrastier result on VC papers using a #47 blue filter than I can with max magenta on my two Chromega heads, so the 170M setting on my heads must pass some light a little closer to green. I use that occasionally only.

 

[snusmumriken]

OK, so where does this leave under-lens filter sets used with a tungsten bulb? Are they sharp-cut filters? Does the effect @Craig reports apply to split-grade printing using them?

 

[Pieter12]

OK, so where does this leave under-lens filter sets used with a tungsten bulb? Are they sharp-cut filters? Does the effect @Craig reports apply to split-grade printing using them?

According to Ilford’s tests (see post 91) comparing under the lens filters with their Multigrade head and Heiland’s LED head, the filters actually perform the best.

 

[koraks]

Koraks, I'll disagree a bit about the interpretation of the curves you linked to. If we were printing step tablets, I'd agree, that the overall tones of a single exposure and a split grade should arrive at the same place. However, a typical photograph is far from a single panel of continuous tone, so the interaction of the range of tones in a scene and how each responds in different parts of the image can create a different effect than a single exposure can. Some parts of the image will react to the #5 filter differently than others, and the same with a #0. That is where Les talked about the global contrast of the image is different than the microcontrast at specific locations within the image.

Craig, density is density, regardless if it's part of a step wedge or an image. There are no magic "interactions" that trick the paper into behaving differently on a step wedge or an image, or that makes the paper do inexplicable magic if you give two consecutive blue + green exposures vs a single exposure with both colors in the same ratio.

There's no smoke and mirrors. I don't know what Les believes or what he has tried to explain in the workshop you took, but I do know it has somehow left you confused. Don't worry though; it's really more straightforward than you appear to think!

 

[Craig]

if you give two consecutive blue + green exposures vs a single exposure with both colors in the same ratio.

Those would be the same. However, that's not what we are talking about in split grade vs conventional printing. We are talking about two distinct exposures of narrow wavelength blue and green, vs a single exposure of a full spectrum source ( the tungsten bulb). The multiple emulsions in the paper can respond differently to those two light sources as Ilford alluded to in the Contrast Control document.

 

[MattKing]

There are no magic "interactions" that trick the paper into behaving differently on a step wedge or an image, or that makes the paper do inexplicable magic if you give two consecutive blue + green exposures vs a single exposure with both colors in the same ratio.

Given the fact that there is usually a cyan sensitive layer as well, there is a possibility that the combined exposure will get you over the threshold when the individual exposures will not.

 

[snusmumriken]

Those would be the same. However, that's not what we are talking about in split grade vs conventional printing. We are talking about two distinct exposures of narrow wavelength blue and green, vs a single exposure of a full spectrum source ( the tungsten bulb). The multiple emulsions in the paper can respond differently to those two light sources as Ilford alluded to in the Contrast Control document.

But nobody seriously prints on MG paper with an unfiltered tungsten light source, do they? Am I misunderstanding you?

 

[MattKing]

But nobody seriously prints on MG paper with an unfiltered tungsten light source, do they? Am I misunderstanding you?

If anyone would, cliveh would

 

[Craig]

But nobody seriously prints on MG paper with an unfiltered tungsten light source, do they? Am I misunderstanding you?

Why not? I've done it plenty of times if my negative fits onto a grade 2 contrast range and gives a print I like. Why introduce filters with the resultant loss of light if I don't need to? I'll leave the filters set to 0 in my colour head and then they are completely out of the light path.

As I mentioned, the Ilford Multigrade paper tech sheet says that unfiltered is an identical contrast range to a Multigrade 2 filter.