A higher contrast blue filter for split-contrast printing

Steve Goldstein · Apr 2, 2020

For a few years now I've been using Rosco R68 "Parry Sky Blue" and Rosco R389 "Chroma Green" filters above the negative for split printing. These are the filters Steve Sherman recommended to me several years ago. The #68 filter alone gave me almost exactly the same contrast as the Ilford #5 filter with slightly shorter exposure times as determined by enlarging a Stouffer step wedge.

A while back I was looking through the Rosco swatch book and noticed that the R68's transmission tail extended into the green above 520nm, where the low-contrast emulsion is sensitive. The R384 "Midnight Blue" filter had much less transmission in the green (and less transmission overall) so I ordered one to try someday. Well, someday came today - I had a negative in the enlarger that printed almost entirely with the R68 so I figured that would be as good a time to compare filters as any.

The R384 filter is definitely slower - I had to more than double the exposure on Ilford Multigrade Classic with my V54-equipped Zone VI cold light head - but the increase in contrast was significant and immediately obvious. And it's cheap, I think I paid $6.95 for a 20" x 24" sheet.

Edit: These plastic Rosco filters aren't optical quality, that's why they need to be used above the negative.

Steve Goldstein · Jun 21, 2021

Over the last year I've been comparing my R68 and R384 blue filters for split-printing various negatives with my V54-equipped Aristo (but branded Zone VI) stabilized cold light head. In all cases I use the R389 green filter and generally the R68 has proven to be just fine; it's the one I reach for first. There were only a couple of occasions when the extra contrast from the R384 made an important difference. It's also nice that the R68 needs less exposure time than the R384 as few things are more boring than standing there for a 230 second (with R384) exposure.

But I have one super-flat negative from which I simply couldn't get a satisfactory print, even with no green filtration, on Ilford Multigrade Classic FB. A print made using the R68 (or Ilford #5) filter was uninteresting while an R384 print was better but still not entirely satisfying; both of these efforts were after selenium-intensifying the negative, which also helped. Going back and rephotographing the subject is completely out of the question. I really didn't want to go down the rat-hole of weird or heated developers just yet so I revisited the Rosco online catalog and looked again at the spectral transmission curves of every blue filter they have in hopes of finding one with even less green transmission than the R384.

The one I found was the "Permacolor P1384 Midnight Blue" filter. While both this and the R384 are called "Midnight Blue", they're quite different. The P1384 has much higher blue transmission than the R384 and a very steep cut around 490nm with NO transmission in the green. Unlike the other filters I've mentioned, the P1384 is glass (not plastic film) and is only available by special order through a Rosco distributor. I nearly fainted when I got the quote - a 6-inch (150mm) square filter was around USD100 plus tax and shipping - so I did what all sensible photographers do and bought it without telling my spousal unit the true cost.

The P1384 filter is amazing! It gives me even more contrast than the R384 and requires less than half the exposure time. It might even need less exposure than the R68 filter. I haven't printed step wedges yet so I can't really quantify the contrast improvement, but it's there in the print. Most importantly, there's finally some life in a print made from my flatter-than-Kansas negative without extensive dodging and burning, which would be difficult for this particular subject.

While I initially envisioned the P1384 filter as a special-purpose tool I now want to experiment with it for routine split printing. I've occasionally noticed that adding the blue exposure slightly darkens highlights compared to my green-only test strips. I believe this arises from the green transmission tails of the R68 and (to a lesser extent) R384 filters. Since the P1384 transmits no green the blue exposures shouldn't affect the highlights at all.

ic-racer · Jun 21, 2021

That is a great find. I did not know Rosco supplied dichroic filters until now. I have dichroic blue and green in my additive head.

john_s · Jun 21, 2021

Is there any filter that could be used below the lens that would get close to that?

Steve Goldstein · Jun 21, 2021

john_s said:
Is there any filter that could be used below the lens that would get close to that?

Sorry, that’s not something I’ve looked into. I’ve always used above-the-negative filters. I don’t know if the glass Roscos would work.

Patrick Robert James · Jun 21, 2021

john_s said:
Is there any filter that could be used below the lens that would get close to that?

The standard for blue/green below the lens filters is to use the combo of 47/58. Those are the Wratten gel numbers, but most manufacturers use the same numbers. The 47 is a deep blue and the 58 is a deep green. For whatever reason it is easier to find the 47 than the 58. You could use Wratten gels below the lens but they scratch easily so getting a round glass filter is usually the easiest. I have it both ways depending on the enlarger I am using. Glass filters for the Leitz Focomat and I put Wratten gels into the frames that come with the Ilford below the lens filters for my Minox enlarger.

Back in the day Oriental used to advise that to get the maximum contrast out of their VC papers you needed to use a Blue 47, not the standard high contrast Kodak/Ilford filters.

Hope that is the information you were looking for.

ic-racer · Jun 23, 2021

john_s said:
Is there any filter that could be used below the lens that would get close to that?

Ilford #5 filter can be used below the lens.

Doremus Scudder · Jun 23, 2021

john_s said:
Is there any filter that could be used below the lens that would get close to that?

John,

I routinely use a Wratten #47 gelatin filter under the lens when 170 magenta on my dichro head won't give me enough contrast. It gives significantly more contrast than the Chromega head an max magenta. Not sure if it would give more contrast than the Ilford #5 filter; I'll have to compare them next time I'm in that situation (which is rarely - really, we should develop our negatives better than that ).

Under-the-lens filters can be smaller, but need to be of optical quality. Wratten gels fit the bill.

Hope this helps.

Doremus

Nicholas Lindan · Jun 23, 2021

A 6x6" dichroic for $100 is a bargain. A 6x6 glass Tiffen 25a will set you back $275.

MarkS · Jun 23, 2021

When I worked for Kodak we had several specialized enlargers and printers. Those used a Wratten #98 for the blue light, a #99 for green, and sadly, I can't recall which red filter the machines had. That was for additive color printing... most of the time we printed in b/w and used the #98 filter (the lenses were optimized for blue light and we were using graded papers). God only knows where you'd find those Wrattens today but if you need the maximum contrast, a #98 is the way to go.

Steve Goldstein · Jun 24, 2021

Mark, that's interesting. I'd never heard of the Wratten 98 and 99 before your post, but found them in my 1990 Kodak filter guide. They're not listed in my 1940 handbook, my 1971-1972 CRC Handbook, or in an undated PDF I have that looks like it came from a CRC Handbook.

The 98 is stated to be the equivalent of a 47B plus a 2B. The 2B is a UV blocker that limits transmission below 400nm so there's probably no difference between a 47B and 98 in black-and-white split printing. I don't have a 47B or a 98 so I can't compare them with my Rosco Permacolor P1384 for contrast.

The 99 is stated to be the equivalent of a 61 plus a 16. The 61 green by itself transmits a bit down to around 490nm, into the blue-sensitive high-contrast region of multigrade papers (and now that I look at it so does my Rosco R389!). Adding the 16 moves the cut to about 520nm, which is in the green. So for the low-contrast exposure the combination of a 61 and a 16 (or a 99 alone, if you can find one) might provide an even lower contrast exposure. Although my R389 does transmit a bit of blue so should increase the contrast of the green exposure, I've never felt limited on the low-contrast side, but if I ever come across a Wratten 16 I'll try stacking it with my R389 and see what happens with a projected step wedge.

I've never seen curves for the Ilford filters.

john_s · Jun 24, 2021

Doremus Scudder said:
John,

I routinely use a Wratten #47 gelatin filter under the lens when 170 magenta on my dichro head won't give me enough contrast. It gives significantly more contrast than the Chromega head an max magenta. Not sure if it would give more contrast than the Ilford #5 filter; I'll have to compare them next time I'm in that situation (which is rarely - really, we should develop our negatives better than that ).

Under-the-lens filters can be smaller, but need to be of optical quality. Wratten gels fit the bill.

Hope this helps.

Doremus

Thanks Doremus, most of my negatives are reasonably easy to print with my Aristo 2-tube VC cold light head. One tube is green and one is violet. I have one favorite negative that I printed years ago on Brovira BEH,a very contrasty paper, and these days I can't do a contrasty enough print on Ilford MG with violet tube only. I wonder if a #47 might give me a bit more contrast. I should probably selenium tone the negative: i've been a bit apprehensive about messing it up though.

MarkS · Jun 26, 2021

Steve, It's not worth looking for a Wratten #98, considering what you already have done. I should have looked it up for you; I still have my copy of the Kodak filter book, and I used to teach the operation of that equipment. But not in 20 years anyway, and that job (and presumably those enlargers) are long gone now. Like my memory of the fine points! Best of luck with your quest... it does occur to me that there are high-contrast paper developers too (although I've never used any).

Nicholas Lindan · Jun 27, 2021

After you reach maximum contrast making the light 'bluer' will have no effect. With blue light you are exposing all the emulsions - blue sensitive and green sensitive (orthochromatic) - at the same time and so the HD curves of the emulsions stack up over each other to produce the maximum contrast the paper can produce: "That's all she wrote..."

See http://www.darkroomautomation.com/support/appnotevcworkings.pdf

john_s · Jun 27, 2021

Nicholas Lindan said:
After you reach maximum contrast making the light 'bluer' will have no effect. With blue light you are exposing all the emulsions - blue sensitive and green sensitive (orthochromatic) - at the same time and so the HD curves of the emulsions stack up over each other to produce the maximum contrast the paper can produce: "That's all she wrote..."

See http://www.darkroomautomation.com/support/appnotevcworkings.pdf

Thanks Nicholas. I had read your article before, it's just that some people have eked out a bit more contrast than their Ilford filters can do on their own, by adding further filtration. I thought maybe I could get some more in the same way. The Aristro tube does look like it's pretty far to the violet, past blue. So to get more contrast, that leaves toning the negative, which seems to work, or maybe higher contrast developer, although I've not read of anyone's great success. I have tried undiluted standard paper developer in the past without seeing much difference.

grain elevator · Jun 27, 2021

Interesting stuff, I've had to resort to lith printing to get the desired contrast out of some negatives, a blue filter might sometimes save me the trouble...

RalphLambrecht · Jun 27, 2021

Steve Goldstein said:
Over the last year I've been comparing my R68 and R384 blue filters for split-printing various negatives with my V54-equipped Aristo (but branded Zone VI) stabilized cold light head. In all cases I use the R389 green filter and generally the R68 has proven to be just fine; it's the one I reach for first. There were only a couple of occasions when the extra contrast from the R384 made an important difference. It's also nice that the R68 needs less exposure time than the R384 as few things are more boring than standing there for a 230 second (with R384) exposure.

But I have one super-flat negative from which I simply couldn't get a satisfactory print, even with no green filtration, on Ilford Multigrade Classic FB. A print made using the R68 (or Ilford #5) filter was uninteresting while an R384 print was better but still not entirely satisfying; both of these efforts were after selenium-intensifying the negative, which also helped. Going back and rephotographing the subject is completely out of the question. I really didn't want to go down the rat-hole of weird or heated developers just yet so I revisited the Rosco online catalog and looked again at the spectral transmission curves of every blue filter they have in hopes of finding one with even less green transmission than the R384.

The one I found was the "Permacolor P1384 Midnight Blue" filter. While both this and the R384 are called "Midnight Blue", they're quite different. The P1384 has much higher blue transmission than the R384 and a very steep cut around 490nm with NO transmission in the green. Unlike the other filters I've mentioned, the P1384 is glass (not plastic film) and is only available by special order through a Rosco distributor. I nearly fainted when I got the quote - a 6-inch (150mm) square filter was around USD100 plus tax and shipping - so I did what all sensible photographers do and bought it without telling my spousal unit the true cost.

The P1384 filter is amazing! It gives me even more contrast than the R384 and requires less than half the exposure time. It might even need less exposure than the R68 filter. I haven't printed step wedges yet so I can't really quantify the contrast improvement, but it's there in the print. Most importantly, there's finally some life in a print made from my flatter-than-Kansas negative without extensive dodging and burning, which would be difficult for this particular subject.

While I initially envisioned the P1384 filter as a special-purpose tool I now want to experiment with it for routine split printing. I've occasionally noticed that adding the blue exposure slightly darkens highlights compared to my green-only test strips. I believe this arises from the green transmission tails of the R68 and (to a lesser extent) R384 filters. Since the P1384 transmits no green the blue exposures shouldn't affect the highlights at all.

if a lack of print contrast happens to you frequently, I wouldn't seek for a higher-contrast filter but developing a higher-contrast negative instead.

Steve Goldstein · Jun 27, 2021

Ralph, this is certainly not usual for me. The negative in question was an image of an inherently low-contrast subject taken on a heavily overcast day towards dusk. And being 120 film, I couldn’t adjust contrast through development without ruining the other images on the roll. In retrospect I should have shot a whole roll of this subject so I could give it more development. The subject is in Peru and I’m in the US, so while I could theoretically go back to reshoot, it would cost many thousands of dollars to do so. Hence my quest.

radiant · Jun 27, 2021

RalphLambrecht said:
if a lack of print contrast happens to you frequently, I wouldn't seek for a higher-contrast filter but developing a higher-contrast negative instead.

This is so true. If one likes more contrasty photos, then please don't be as stupid as me and develop "by the book", make sure your negatives are contrasty to begin with.

Nicholas Lindan · Jun 27, 2021

I have one negative of a high school girlfriend taken by the light of a rather distant single candle. It was the classic "available darkness" shot. It could only be printed on Brovira grade 6 (and even that was not quite enough). Utterly impossible to print on MGIV. So I know the desire for more contrast.

Back in the dawn of time the solution was chromium intensifier. But I could never get that to work to my satisfaction.

The modern solution would be a really good scan of the negative and cranking the curves in Photoshop. Hmmm, I think I'm going to see if I can find that negative.

ic-racer · Jun 27, 2021

High contrast paper developer is the answer, as suggested already.

Doremus Scudder · Jun 28, 2021

There are a few things you can do to get more contrast out of a flat negative.

Using a contrastier print developer and finding the filtration that gets you maximum contrast out of your VC paper have been mentioned.

If those things don't work you can intensify the negative. There are a couple of ways to do this without resorting to chromium intensifier (if you can even get it these days...).

If your neg would benefit from an approximate one-Zone increase in contrast and it was not developed with a staining developer to begin with (e.g., Pyrocat or PMK), then you can selenium intensify the negative. As mentioned, this gets you 1/2 - 1 grade of change and won't work well with negatives originally developed in a staining developer (it removes the stain).

If you think you'll need more contrast and/or your negative was developed in a staining developer, then I'd recommend bleach/redevelop, using a staining developer like Pyrocat or PMK to redevelop with.

My procedure for bleach/redevelop is simple:

15g potassium ferricyanide
15g potassium bromide
1 liter of water

Presoak the neg in water for five minutes, then bleach until the image is completely gone. A very faint tannish-looking residual image will remain. Rinse the bleach off then redevelop in the (staining) developer of your choice. Don't worry about over-developing, you need to develop to completion. Err on the side of longer. Your "normal" time plus 10% or so will do just fine. You can do it all with the lights on. Save the bleach solution for future use; it lasts forever.

This gives a gratifying amount of contrast increase.

Best,

Doremus

MattKing · Jun 28, 2021

For clarity, the various negative intensification options work well with well exposed, under-developed negatives.
There isn't a lot that helps with negatives that are low in contrast because they have been under-exposed.

Doremus Scudder · Jun 28, 2021

MattKing said:
For clarity, the various negative intensification options work well with well exposed, under-developed negatives.
There isn't a lot that helps with negatives that are low in contrast because they have been under-exposed.

Matt makes a good point here.

I'd like to add, though, that I've seen a gratifying increase in shadow detail when using the bleach/redevelop method. It won't save featureless shadows - nothing will - but it does boost the low values that are there proportionally.

Doremus

DREW WILEY · Jun 28, 2021

Use real glass filters below the lens. Don't use polyester pseudo-gels down there, or similar VC printing filters, or the sharpness will be compromised. Tiffen still makes a deep blue glass 47 filter in multiple sizes. I've actually gotten fully rich VC prints using deep blue only exposures from negs with just the yellowish pyro stain being visible, and not any silver density itself apparent at all. That should tell you something. You wouldn't think anything was even any exposure there unless you viewed the neg atop a lightbox through a blue filter first.

That was a special direct pyro developer tweak (no bleaching step to remove the silver) that worked only with a previous version of HP5. I don't know why that was the case, but it rendered elegant prints.

A higher contrast blue filter for split-contrast printing

Steve Goldstein

Steve Goldstein

ic-racer

john_s

Steve Goldstein

Patrick Robert James

ic-racer

Doremus Scudder

Nicholas Lindan

Advertiser

MarkS

Steve Goldstein

john_s

MarkS

Nicholas Lindan

Advertiser

john_s

grain elevator

RalphLambrecht

Steve Goldstein

radiant

Nicholas Lindan

Advertiser

ic-racer

Doremus Scudder

MattKing

Moderator

Doremus Scudder

DREW WILEY

A higher contrast blue filter for split-contrast printing

Advertiser

Advertiser

Advertiser

Moderator

Privacy & Transparency

Privacy & Transparency