Tri-x 400 at 25,600

[Gerald C Koch]

Jerry, I've seen and been told that about the latensification with green light, very dim and very far away. Clair Senft uses it with her Imagelink-HQ and a peroxide latensifier too.

Nobody has ever told me why it has to be a green light, the peak of human light sensitivity. B&W film is sensitive over a wider range as you know, so why green? TIA
Murray

Hi Murray,

That's a very good question. The books I have read never mention a specific wavelength to use. I assume it doesn't really matter. The sites are going to activated regardless of the wavelength used if it is within the sensitivity of the film. This is a guess but using a green safelight may be only for the users benefit. After setting up the film and the safelight you have to be able to see enough to get out of the room.

 

[2F/2F]

6400 is a 4 stop push. I would argue that you are not really "pushing to" an EI that high, just that you are underexposing that much, and developing and printing in a certain way to compensate for it. A true four stop push means that something that falls on a Zone IV equivalent density in the case of normal development is pushed up to a Zone VIII equivalent density with overdevelopment. Some common film/dev combos have trouble even getting to a true two stop push (in which a Zone VI fall is pushed up to a Zone VIII equivalent density). Getting a true three or four stop push is near impossible in most film/dev combinations that people use.

So, beyond a certain point, it is confusing calling it "pushing to such and such EI;" that point would be the point at which you can accurately compensate for highlight underexposure by overdeveloping. Past that point, you are basically just overdeveloping roughly in order to get a printable negative. It cannot really be said that you are "pushing to" a certain EI unless a tone that should have fallen on Zone VIII if normally exposed (but does not do so due to the underexposure caused by downrating) ends up back at Zone VIII density after development.

I think Athiril made the same point about the inaccuracy of pushing past a certain point in his last post, but I would put the point of accuracy and of true underexposure compensation for the mids and highs well below EI 6400 with Tri-X. I think that anything past or 2,000 or 2,500, and you are basically just developing a lot to help you out; you aren't attaining a true push "to" a certain EI.

I think it is much easier to discus pushing and avoid confusion if exposure and development are treated as two separate things. That means EIs should not be used in reference to development, only to exposure. Go past a certain point of underexposure/uprating, and you cannot really push "to" a certain EI. You just take desperate development and printing steps in order to salvage an underexposed negative.

I underexpose films past two stops all the time. It is necessary sometimes, and a lot can be done to dig a print out of such foul negatives, as Athiril has shown. But I don't fool myself in to thinking that I can truly achieve underexposure compensation through development when underexposing past a certain point. So I don't think of development in terms of pushing "to" any particular EI. I try to judge the light and the exposure I was forced to make, and then take development steps that will best give me a printable neg given where things have fallen with exposure. Simply calling this "pushing to" a certain EI is inaccurate and doesn't give this very involved process it the credit it deserves. It oversimplifies the thought processes and gets people thinking they can do things that they cannot.

 

[BetterSense]

That's what I wanted to say when I made my post, but I wasn't articulate enough to say it.

 

[Murray Kelly]

I am sometimes given to wondering if stretching credibility of a film ( to put it another way) would benefit from using microfilm developers. I have no particular evidence of this but to extend the gray scale of a film that has nothing in the shadows (by definition, it seems) would benefit from a developer that suits the pictorial rather than the usual contrasty developers we're talking about for that sort of film.

I suggest the usual suspects - H&W, Technidol, Soemarko's Lith film dev, and a couple of newer ones presented on PN. I'm sure you can all think of some others.

What, with a bit of a flash, and some ultra low contrast developer and paper, just maybe one could get a picture at ridiculous EIs?,

50 years ago, when Tri-X came out there was an article in one of the photo mags on exposing it at 12,000 and how to go about it. Could have been something for a bit of a laff? I tried, and got some shots, with which I was happy. Do 'not' ask me details. Memory hath its limits. I still have the negs.

I am broadminded enough to think the OP will have some fun and learn a lot even if he has to teach himself.

 

[michaelbsc]

Pushing works best with uniformly lit low contrast subject matter. Unfortunately, most pushers try it with very contrasty lighting like street lights or stage lighting and the results are (to my sensibilities) execrable. Stage and street lighting should be pulled - Tri-x exposed at ASA 50 and underdeveloped by 50%.

This really depends on the effect you want.

For example, I've been monkeying with some night shots, but doing long exposures to get sufficient light. But looking at the results it's clear that what I'm really looking for is *EMPTY* shadows and blown out lights to convey the feeling of night time.

So what I'm about to decide is that I really do want to push so what would be zones 4-7 in a "normal" scene become zones 2-9 in my image. And I don't care if the street light blows out; that's part of conveying the image.

Granted that this is a different effect than what you're talking about. But I am relating my findings about "learning" my materials here. I've spent time finding out that my analysis of what I wanted was totally wrong.

MB