Have I Had An Epiphany?

[Stealth3kpl]

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...or am I still thrashing about in the dark?

I watched this video. That wasn't anything new to me. It's what I've been doing. But then in this thread, Otto asks "I don’t understand actually why you would want ISO 200 with TriX in the first place". I've been thinking about that. Although I gave my reasons at the time, I think I've been going about it all wrong. So I've been exposing at 250, but pulling development. As, in the video, this maintains the contrast. Now I'm thinking if I'm to keep my shadows open I should have been shooting at 250 but not pulling development i.e. developing as if shot at 400. My next film I'm thinking of trying this theory, but am I wrong? Increasing development time should open up the shadows, shouldn't it? I think it will give a higher contrast negative whereas I've got it in my mind that a lower contrast neagtive might be better for scanning so I'm a little concerned about my thinking. Should I try shooting at 250 and develop for 400? 

Pete

[ianman]

I've been doing this with Portra. Exposing at 200 or 320 and getting it developed at the box speed 400. Thus overexposing. The goal being to protect the shadows. At least, that's my understanding. 

Since getting back into film, I've been using B&W at box speed... until now, I have put in some Acros which I am exposing at 400 and going to develop at 400. But yes, at some point very soon, I'm going to try deliberately overexposing some HP5 (exposing at 200, developing at 400).

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[Stealth3kpl]

I also shoot colour c41 a stop over. I can't think how I've been developing my B+W for 250 rather than 400 for so long. I'm sure developing for 400 is the right thing to try looking at my scans, but I must make more of an effort to expose for the darkest of the shadows, I think. Take this one for instance. I was quite sure I'd found the darkest incident reading to expose for, but it is still quite underexposed beneath the chin giving that grainy look when I try to bring the brightness up.

Pete

 

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Edited October 20, 2018 by Stealth3kpl

[Stealth3kpl]

I realise that for low contrast scenes, some might rate triX at 800 and increase development time 10% or so, or conversely, for a high  contrast scene rate at 250 and reduce dev time 10% or so. I guess I'm just trying to get a better range of tones in a "normal" scene, and thus find the right film speed for my way of doing things. Maybe I should just expose for 400 and vary development time. I'm just thinking out loud.

Pete

[pico]

Pete, one of the shortcomings of advising on a forum is that your ISO 400 might be my ISO 250. Really, it took me some time to reconcile hand metering to in-camera readings.

Eventually I shot Tri-X (the pre-1970 formula) at 250 and developed normally and printed in a Focomat, a condenser enlarger. So many variables.

Very best of luck.

[Stealth3kpl]

Thanks Pico. And this film is Neopan 400 which has been in the freezer for 10 years so of course, it may well have lost some speed.

Pete

Edited October 20, 2018 by Stealth3kpl

[Chuck Albertson]

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On ‎10‎/‎20‎/‎2018 at 9:47 AM, Stealth3kpl said:

 Increasing development time should open up the shadows, shouldn't it? I think it will give a higher contrast negative whereas I've got it in my mind that a lower contrast neagtive might be better for scanning so I'm a little concerned about my thinking. Should I try shooting at 250 and develop for 400? 

Pete

"opening up the shadows" is a function of exposure, not development. If there isn't sufficient exposure for shadow detail, no amount of development will add detail (only density). I don't know what developer you use for Tri-X, but by all means give the 250/400 development a try and see if you like the results - what works best for you is all that matters.

[Stealth3kpl]

11 hours ago, Chuck Albertson said:

"opening up the shadows" is a function of exposure, not development. If there isn't sufficient exposure for shadow detail, no amount of development will add detail (only density). I don't know what developer you use for Tri-X, but by all means give the 250/400 development a try and see if you like the results - what works best for you is all that matters.

Ah, yes, I'm overexposing a stop. Varying development affects contrast of the negative. Does it affect highlight development more than shadow development ? I've heard that shadow development is very quick, and highlight development is affected more by variables such as agitation and time.

pete

[Ambro51]

...thinking along another path.....consider using a yellow filter.  

[Stealth3kpl]

2 hours ago, Ambro51 said:

...thinking along another path.....consider using a yellow filter.  

What is your thinking here?

Pete

[Ambro51]

You’ll make subtle changes is the image contrasts/ shading that may fit your needs.  Try it.

[adan]

Just for the record, there is quite a difference between how chromogenic (C-41) films react to overexposure and normal development, compared to all-silver B&W films.

When C-41 film is developed, the final image is formed of soft-edged translucent dye clouds. The more the exposure, the more those clouds grow and overlap and blur together (reduced graininess). That - BTW - includes the "monochrome C-41" films like Ilford XP2 or Kodak TMax CN.

With pure-silver films, the hard-edged silver grains themselves just get bigger and bigger with more exposure (more graininess).

As to the original question: Bottom line, developing silver film as though it was exposed at 400 when it was really exposed at 250 (always allowing for Pico's point - whose "250?") will mean increased contrast and density overall. Which will kind of spoil the idea of exposing for "more open shadows."

Because development acts on the film density by multiplication. Take a neg exposed at 250 and develop it for 250, and you perhaps get an open shadow density of 0.4, and a highlight density of 0.9. (a difference between the densities of 0.5). Give 50% more development as though for ISO 400, and you'll get densities of 0.6 and 1.35 (a difference of 0.75). The highlights have increased in absolute density more than the shadows have - so much for "open shadows".

By the time you've increased your scanner exposure to penetrate that higher highlight density, your shadows are dark again, and less open. (Of course, you can spend a lot of time in post-processing to try and open them up again).

Thus the mantra "Expose for the shadows, AND develop for the highlights (because development won't help/hurt the shadows as much)" And pulling the development is "developing for the highlights." To keep them from getting too dense. The two go together.

All that being said, the difference between ISO 250 pulled development and normal 400 development is not all that large (should be about 0.8:1), and won't "ruin" a negative. But if you were doing some serious Zone System work with a contrasty subject; that called for, let us say, an N-3 development (maybe 38% or "normal" - a three-stop pull) - but give it the normal (N) development, you'd end up with an ugly negative - dense to the point of being blocked in the highlights (in digital terms, "blown") and perhaps even unscannable, and excessively grainy.

[pico]

One day I am going to experiment with gross over exposure and development to push the image up and over the upper shoulder - using 4x5 film. Certainly print times will be terrible. Do you think it might lead to an interesting look regarding shadows and highlights?

 

[Stealth3kpl]

52 minutes ago, adan said:

Just for the record, there is quite a difference between how chromogenic (C-41) films react to overexposure and normal development, compared to all-silver B&W films.

When C-41 film is developed, the final image is formed of soft-edged translucent dye clouds. The more the exposure, the more those clouds grow and overlap and blur together (reduced graininess). That - BTW - includes the "monochrome C-41" films like Ilford XP2 or Kodak TMax CN.

With pure-silver films, the hard-edged silver grains themselves just get bigger and bigger with more exposure (more graininess).

As to the original question: Bottom line, developing silver film as though it was exposed at 400 when it was really exposed at 250 (always allowing for Pico's point - whose "250?") will mean increased contrast and density overall. Which will kind of spoil the idea of exposing for "more open shadows."

Because development acts on the film density by multiplication. Take a neg exposed at 250 and develop it for 250, and you perhaps get an open shadow density of 0.4, and a highlight density of 0.9. (a difference between the densities of 0.5). Give 50% more development as though for ISO 400, and you'll get densities of 0.6 and 1.35 (a difference of 0.75). The highlights have increased in absolute density more than the shadows have - so much for "open shadows".

By the time you've increased your scanner exposure to penetrate that higher highlight density, your shadows are dark again, and less open. (Of course, you can spend a lot of time in post-processing to try and open them up again).

Thus the mantra "Expose for the shadows, AND develop for the highlights (because development won't help/hurt the shadows as much)" And pulling the development is "developing for the highlights." To keep them from getting too dense. The two go together.

All that being said, the difference between ISO 250 pulled development and normal 400 development is not all that large (should be about 0.8:1), and won't "ruin" a negative. But if you were doing some serious Zone System work with a contrasty subject; that called for, let us say, an N-3 development (maybe 38% or "normal" - a three-stop pull) - but give it the normal (N) development, you'd end up with an ugly negative - dense to the point of being blocked in the highlights (in digital terms, "blown") and perhaps even unscannable, and excessively grainy.

Once again, thanks for taking the time to explain this. I think I'll try exposing at iso 400 but metering more carefully, then develop for 400.  I think I've been barking up the wrong tree.

Pete

[Stealth3kpl]

Is pushing TriX to 1600 a myth? In doing so, the film is underexposed. The increased development time increases contrast in the image. 

Getting confused

Pete

[ianman]

Pushing Tri-X to 1600 is only 2 stops. I've heard of people pushing it to 3200. Yes, the result, after a longer development time,  will be more contrast and more grain.

[adan]

If you use the ISO (International Standards Organization) standard or definition for determining ISO film speed:

For black-and-white negative film, the "speed point" M is the point on the curve where density exceeds the base + fog density by 0.1, when the negative is developed so that a point N where the log of exposure is 1.3 units greater than the exposure at point m, has a density 0.8 greater than the density at point m.

(translation: the speed of a film is that "ISO" that will produce "normal" shadow detail with "normal" development and a "normal density range" to the whole negative)

.....then yes, it is technically a myth. No amount of pushed developing of TX exposed at 1600, will result in the same or "right" amount of shadow detail as TX shot at 400 and developed normally. For the same reason already noted - additional development is multiplicative. It will mess up that M=0.1/N=0.8 density relationship.

Some compensating techniques or developers can squeeze out the absolute maximum amount of shadow detail to meet the ISO test, but not really more than 1/2 stop or so (ISO 640, maybe) to satisfy the ISO definition. Silver photography is magical, but it can't fight physics. Not enough photons = not enough silver.

_________________

HOWEVER, if your standard is "a usable picture in dim light," you can throw the ISO technical definition out the window, and just use the definition "I got a usable picture." And in that case it is not so mythological. Ideally, one would call it an EI (exposure index) rather than an ISO (since it doesn't meet the ISO definition).

Ideally, a "good push" would mean that a gray-card gray (not a shadow tone) comes out with about the same silver density as an unpushed negative, and about the same total amount of silver in the negative, but redistributed (less than normal in the shadows, about normal for a gray-card gray, and more than normal in the highlights).

A "heroic push" as in the sample below, means a negative that with "heroic" measures in the darkroom (high-contrast paper, dodging, burning, maybe ferricyanide bleaching) can still produce a final picture. Just barely enough silver in the film - with any amount of film development - to coax out the necessary tonal distinctions to reveal the subject. I shot with a 28mm f/3.5 lens, under the "available darkness" of one 500-watt floodlight 40 meters/yds from the subject (back over my shoulder). I didn't really "pick" an EI for my TX - I just shot to avoid camera shake; 1/15th at f/3.5. Then I took an incident meter reading (which showed that that exposure in that light was about equivalent to EI 4000). I then just developed the film for "infinity" (30 minutes or so), and accepted the very thin neg that resulted (see simulated neg densities in the "negative" version).

Definitely not really ISO 4000, or even close, according to the amount of shadow detail/density the ISO standard calls for - but just enough mid-tone/highlight density for a dramatic picture.

In any case, you will start to see the classic "charcoal and chalk" look of pushed film with more than a 1-stop "push" -  a few mid-tones that are "about right," with increasingly inky black shadows and nearly blank white highlights everywhere else. Contrasty.

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