Update on the Pyro Study

[sanking]

Some weeks ago I announced that Kirk Keyes, Tom Hoskinson and I would be doing a study of staining versus non-staining developers. We are convinced that such a study should be useful because there is so much confusion, myths and uncertainties out there about this subject.

It took a while to get the study started but finally after gathering materials I began my initial part of the study, which deals primarily with the use of sensitometry with these two types of developers. As some of you know, my opinion is that negatives developed in staining developers will print on graded sliver papers with the same, or very similar, reproduction of tonal values, as negatives developed in non-staining developers, if the two types of negatives are developed to the same effective CI. This assumes of course that the readings by densitometer will be done in a Mode or with a cut-off filter than closely approximates the spectral sensitivity of the paper. For graded papers this sensitivity is in the blue band of wavelength.

At this point I have carried out extensive testing with two different staining developers and four different films, two traditional emulsions and two T-grain emulsions. As a result of these tests I am able to state as an absolute fact about which there should be no discussion that graded silver will print the same with staining and non-staining developers when both are developed to the same effective CI.

As clear evidence of this fact I am attaching two sets of curves. One is a family of curves using the same film but four different developers, two staining and two non-staining. The time of development was such that a close range of negative CI was obtained, ranging from .63 to .65, specifically as follows. The CI for all of the negatives, whether developed in a staining or non-staining developer, was determined by reading with a densitometer using a broad band blue aperture, and the plots were made using Phil Davis' Winplotter program.

Blue Curve .63
Red Curve .65
Black Curve .66
Green curve .67.

The other is a set of paper curves made on Ilford Galerie FB #2 paper from the four negatives. If you look carefully at the curves you will see that they are virtually identical, the only difference being a slight difference in contrast that results from the range of negative CI from .63 to .67.

Since this is an on-going project I won’t identify the film and developers here, but it will all be included in the study, together with results from the other three films, which I will state here for the record show the same kind of result.

The next step is to try to make some sense out of the use of staining developers with VC papers.

Sandy

 

[noseoil]

Sandy, first thank you for this study. It will be interesting to see what happens with respect to VC papers and staining developers. Hopefully it will shed some light on the staining / non-staining grade printing debate.

I'm curious about the Ilford Galerie FB grade 2. Is it close enough to the old grade 2 azo for enlargement with the same negative? Thanks, tim

 

[Gerald Koch]

Thank you for undertaking this study and the large amount of work involved. I eagerly await your final results.

Jerry

 

[sanking]

Sandy, first thank you for this study. It will be interesting to see what happens with respect to VC papers and staining developers. Hopefully it will shed some light on the staining / non-staining grade printing debate.

I'm curious about the Ilford Galerie FB grade 2. Is it close enough to the old grade 2 azo for enlargement with the same negative? Thanks, tim

I was also very surprised by the long exposure scale of Galerie FB Grade 2. It does appear to me that a negative developed to a DR of about 1.50 (or CI of about .67-.70) for printing on the old AZO 2 would print well on this paper. I was quite surprised by the results but after testing both a TP 45 step wedge and some real negatives developed to a DR of about 1.5 the long ES seems to be real.

Just by way of explanation, the Stouffer TP 45 step wedge has 21 discrete steps of density, each different from its neighbour by about +/- log 0.15 steps. Starting at Step 1, which has a density of about 0.05, the density increases by log 0.15 for every step. For example, Step 2 has a density of approximatley 0.20, Step 3, 0.45, Step 4, 0.60, etc. If you contact print the Stouffer TP 45 directly to a piece of Galerie FB Grade 2 (exposing so that you get several steps of maximum density and several steps of paper white) and develop the test in D72 (like Dektol) 1:2, you should count 11 steps of different density (at least I did), ranging from the first absolute maximum black to paper base white. Eleven steps would correspond to an exposure scale of 1.65 (11 X 0.15). However, in silver printing we generally set the plot for 90% of Dmax, which adjusts the ES back to about 1.50.

Sandy

 

[Michael Kadillak]

Sandy, first thank you for this study. It will be interesting to see what happens with respect to VC papers and staining developers. Hopefully it will shed some light on the staining / non-staining grade printing debate.

I'm curious about the Ilford Galerie FB grade 2. Is it close enough to the old grade 2 azo for enlargement with the same negative? Thanks, tim

Amazing that this paper would print to this density range. What kind of tonalities does Galerie FB Grade 2 exhibit? Is it warm or cold and what developer do you use with it. Have you contact printed with it? Might be a great proof paper for Azo grade 2 as well.

Thanks to Sandy and the rest of the research team for all of this hard work. I hope that these conclusions academically conducted and well documented will take all of the emotion out of this subject once and for all.

Cheers!

 

[Jim Fitzgerald]

Sandy, thanks to you and your "team" for doing this. I always value your testing data and results. I love the Pyrocat HD and the results that I get. Keep up the good work!

Stay Focused....or Soft Focused!!

Jim

 

[Jim Noel]

Sandy,
Thanks for doing the study. I too am amazed at the scale of the paper. It will be interesting to read the results by the other testers as time moves along.

One of the things I really appreciate about Pyrocat HD is the very clear film base and the resulting shorter printing times. I intend to continue using it even if no other advantage is evident from the tests.

Jim

 

[Donald Miller]

Sandy, Thanks for doing all of this work. It must be daunting when you get into VC materials.

 

[don sigl]

Sandy:

A few years back I read this article on determining density readings for staining negatives: http://www.unblinkingeye.com/Articles/Densi/densi.html
I own a UV densitometer and note that the density readings under a UV filter are higher for pyro negatives than if Iread the negatives under a blue filter. Do you think using UV readings would change your results?

Regards,

 

[ongarine]

Thank Sandy and all the staff working on the Pyro negatives printed on VC papers.
Hope this helps all the people, me first, to have a better approach with VC paper in darkroom with pyro negatives to print.
About printing paper for the tests: consider also Emaks fiber grade 2 (know under many brand in UE and US) you could have nice surprises.

 

[sanking]

Sandy:

A few years back I read this article on determining density readings for staining negatives: http://www.unblinkingeye.com/Articles/Densi/densi.html
I own a UV densitometer and note that the density readings under a UV filter are higher for pyro negatives than if Iread the negatives under a blue filter. Do you think using UV readings would change your results?

Regards,

I am very familiar with that article by Bob Herbst. Bob's work with UV densitometers was very important in revealing just how much difference there is in effective printing contrast with stained negatives between Blue and UV measurment when printing in Pt./Pd. (or other alternative processes).

Without question the readings of a stained negative with a densitometer will be higher in UV mode than in Blue mode. Therefore, if you are printing with processes that have high sensitivity to UV radiation (basically, most of the alternative processes, including albumen, carbon, kallitype, Pt./Pd. salted paper, vandyke, etc.) you will get a much more accurate idea of the effective printing CI of your negative by taking the reading in UV mode.

My densitometer, which is a Gretag D 200-II, takes measuring tubes corresponding to a fairly wide range of center wave lengths, ranging from UV at 373 nm to red at 638 nm. I personally have tubes for UV, with the center band length at 373 nm, blue with the center at 458 nm, and green with the center band length at 555 nm.

If your densitometer readings are to provide an accurate indicator of the effective printing contrast or CI of your negatives it is essential that the readings be taken through a filter that closely approximates the spectral sensitivity of the process. Graded silver papers are most sensitive to blue light in the 400-500 nm range so that is the color filter you should use to measure negatives that are to be printed on these papers. The theory is sound, and it works in practice. Same is true for UV sensitive alternative processes. You measure with a filter centered on UV light at about 375 nm and you get a very good idea of the effective printing contrast of the negative.

VC silver papers are much more complicated because they have sensitivity both to blue (high contrast) and green (low contrast) light. This has implications not only for densitomter readings, but also for the color of exposing light source.

Sandy King

 

[Kirk Keyes]

This has implications not only for densitomter readings, but also for the color of exposing light source.

Speaking of which - what color source are you using for the prints? I can send you my Minolta Colormeter II to measure the color temp if you like.

Kirk

 

[sanking]

Speaking of which - what color source are you using for the prints? I can send you my Minolta Colormeter II to measure the color temp if you like.

Kirk

For the prints on graded silver paper I used a small tungsten lamp, a Philips 7.5 watt night light, white frosted. Since the paper is sensitive only to blue light from about 400-500 nm, and to UV down to about 375 nm, the color of the light does not affect ES. I actually tested this by exposing with Blue (470 , UV (cut-off below 400 nm) and green (58) cut-off filters. The resuslt wasnNo exposure at all with green filter, and longer exposures with either blue or UV cut-off filters (but no change in exposure scale with either stained or non-stained negatives).

Since the small Philips tungsten bulb puts out both blue and green light I will probably continue with it for the VC tests. It might be less trouble and expense for you to pick one of these up at a Home Depot or Lowes and test it yourself rather than send me the meter?

Sandy

 

[Kirk Keyes]

It might be less trouble and expense for you to pick one of these up at a Home Depot or Lowes and test it yourself rather than send me the meter?

It might be, but then it might not be quite the same as an actual measurement.

Is this the bulb? Philips night light I saw other bulbs there that were nice, shperical bulbs, but they were blue or green, and not white.

I would expect a bulb like this to be relatively low in color temp, especailly compared to someone with a enlarger that uses halogen bulbs. My Saunders 4500 temp measures around 3300 K, if I remember right. A low wattage incandescent bulb like your nite lite could be as low as 2700K or less. That would make it quite a bit yellower than the enlarger, thus less blue light. I've got a spread sheet at home that graphs black box temps, I'll see if I can make a graph to compare later.

Kirk

 

[sanking]

It might be, but then it might not be quite the same as an actual measurement.

Is this the bulb? Philips night light I saw other bulbs there that were nice, shperical bulbs, but they were blue or green, and not white.


Kirk

That is not the one, and I was not able to find it at the Philips site. But I have another one and there are more at the store so can send you an identical bulb if necessary.

The issue of how color temperature of the light source works in conjunction with VC filters to control contrast (with the added complication of stain) appears to be fairly complicated.

Sandy

 

[Kirk Keyes]

But I have another one and there are more at the store so can send you an identical bulb if necessary.

That would be cool. It would be interesting to compare with my enlarger.

Kirk

 

[sanking]

That would be cool. It would be interesting to compare with my enlarger.

Kirk

I have been tryng to contact you by email today but my mail server program is down. You have my email so just send me your address and I will get the bulb out to you right away. I have some more comments and questions in the email and hopefully it will go out soon.

Sandy

 

[lee]

Sandy,

have you seen any of the pinholing issues yet with Pyrocat and Hp5+? I would like to use that film in largeformat but have been reluctant to do so because of the pinholing.

lee\c

 

[sanking]

Sandy,

have you seen any of the pinholing issues yet with Pyrocat and Hp5+? I would like to use that film in largeformat but have been reluctant to do so because of the pinholing.

lee\c

Lee,

Go look at that pinhole thread in a few minutes. I do have something to say about it.

Sandy

 

[Kirk Keyes]

My Saunders 4500 temp measures around 3300 K, if I remember right. A low wattage incandescent bulb like your nite lite could be as low as 2700K or less. That would make it quite a bit yellower than the enlarger, thus less blue light. I've got a spread sheet at home that graphs black box temps, I'll see if I can make a graph to compare later.

Sorry - no time for a graph these days, but looking at my blackbody spreadsheet calcs, I get that a 2600 K light has about 9% of it's output in the blue range and about 30% in green, while a 3200 K light has about 15% blue and 33% in green. It seems like that could be a significant difference with a VC paper. As to how many CC yellow that is, I'm not sure.

(These are probably overly simplistic approximations on my part, as I pretty much just normalized the black body output to make the maximum intensty equal to 1, and then integrated the area from 400-500 nm as blue, 500-600 as green, and 600-700 as red. As a check, for 5500 K, I get a pretty equal balance between these 3 colors with 32.5% B, 35% G, and 32.5% R. But it should give a idea of the differences in color at different temps.)

Kirk