How much density can be increased while pushing?

radiant · Oct 17, 2021

When developing B&W negative film and "pushing" the film, how much one can boost the density of the negative by development?

For example: you heavily underexpose the film and your "highlights" are just around the toe of the film. How much can you increase the density for these tones?

I made a test exposing HP5 at EI 6400 and developing in Xtol 1+1 for 45 minutes (30 sec agitation cycle). Maybe not a surprise but low SBR scenes came out very thin ..

osella · Oct 17, 2021

I don’t often push film, but I’ve run into a similar issue when developing negatives for pt/pd prints in Xtol. I wasn’t giving the film enough exposure so couldn’t get the required highlight density even with very extended development times.

I’m my experience Xtol isn’t the best at getting the most possible density. I got more density using PQ universal, but there was still a limit. There is only so much silver halide to be converted in the developer and you might have found that limit.

Ulophot · Oct 17, 2021

You might try paper developer, which is more active.

Andrew O'Neill · Oct 17, 2021

I did a push test a few months ago with my main film, HP5 (EI 12800). I gave 5 stops less, and developed like hell in Xtol-R. I was shocked at how well the image turned out. Of course there were shadow areas that were lost, but overall, I was pretty happy. Probably more shocked than happy. I believe that the 5 stops was a limit, though... and I don't think I would ever do that with the type of photography that I do...open, luminous shadows.

radiant · Oct 18, 2021

Thanks for the answers!

I know it is possible to increase density from the toe area but how much? It probably depends on developer of course. Can one max out the film density that was originally "exposed" to the toe area?

FotoD · Oct 18, 2021

vedostuu said:
Can one max out the film density that was originally "exposed" to the toe area?

I would expect so. If you pre- or post-flash the film.

radiant · Oct 18, 2021

FotoD said:
I would expect so. If you pre- or post-flash the film.

Flashing is exposure.. What about without flashing?

radiant · Oct 18, 2021

@michael_r good explanation!

So there is limited amount of "stretch" for certain tones before you develop so long that fog appears on shadows. I assume (box speed) midtones can be developed to highlight densities? What about zones III or IV - any luck there?

Would it be possible to get highlight density for original toe with crazy amount of development? If we forget that fog is also increased?

radiant · Oct 18, 2021

Let me put this way: how much can you "push" a film with maintaining good density on highlights?

Of course it depends on film and developer .. but is there some kind of thumb rule or experiences - anyone?

radiant · Oct 18, 2021

Maybe put in short:
- yes, probably toe could be developed to "full" density ..
- but: fog is the enemy.

BTW: I've always thought paper doesn't gain any blackness after certain point (because we develop it fully) - I have never left the paper for that long. You learn new stuff every day!

What I'm trying to achieve is to understand how film development behaves so I can manipulate it to my liking and achieve certain look. What I have done is some long developments (double time) to achieve salt printable negatives. I haven't yet seen any fogging of shadows so that is why I was interested if by just developing for ages one could establish printable range negatives. But now I know there is limit; fogging. My experience has been that if I underexpose shadows well enough, they don't grow density at all - which is really good in terms of increasing the negative dynamic range.

For sure if you develop box speed exposed film for long, the VII will grow density. I've understood that it is not behaving completely "digital" or "clamping" - the shoulder compresses the highlights. Of course those are difficult to print but I've recovered pretty powerful skies from really dense highlights. But yeah, if you really overdo it, then the contrast of the highlights will probably fall down and compress to similar density. I've understood that there is long way to that point however.

Mr Bill · Oct 18, 2021

Hi, I've occasionally referred to this article on the internet. Although it doesn't carry out development to an extreme degree, it does show a very wide exposure range. It may help to answer some of your questions.

https://www.photrio.com/forum/threads/where-would-film-technology-be-now.171630/page-3#post-2234973

The article was intended to show the maximum luminance recording range of the Tmax films, which were fairly new at the time. Not what you are asking about, but again, maybe of some interest to you. For those who are not familiar, the x-axis (side to side) shows the relative exposure in log units, where each change of 0.30 log units is equivalent to one full f-stop. A "normal" sort of exposure, then, will be on the left side of the graph.

Nikola Dulgiarov · Oct 18, 2021

vedostuu said:
Let me put this way: how much can you "push" a film with maintaining good density on highlights?

Of course it depends on film and developer .. but is there some kind of thumb rule or experiences - anyone?

Mr Bill's reference to the family of curves is quite relevant, because it demonstrates graphically the tendencies as development time is increased. Of course, the behavior would be different for different types of developer (single agent vs superadditive/ETA, solvent vs nonsolvent, etc). Nonimage density increases, as does contrast, and I guess one can look at the relative rates to determine the 'maximum' gain in pushing. I've 'seen' examples of 4-5 stop pushing online, where the image characteristics have not been degraded as significantly as one might assume. Such extremes are better pulled off with traditional slow to medium speed films, so trying to push Tri-X or HP5 to 12800 or some similar acrobatics will still result in negatives that are hard to print, lack gradation, are exceedingly grainy, etc. For some, that might be an acceptable tradeoff or a sought-after effect.
I was once given a few rolls of 16 mm Tri-X shot at a night-club and globally in low-light conditions. I managed to recover the information in the film (on average a 3-4 stop push) by using a strong PQ developer (probably Ilford Multigrade at print dilution) and development times upward of 40 minutes. I did have the benefit of reversal processing, but nevertheless, the results were more punk than the student had hoped them to be..

Nicholas Lindan · Oct 18, 2021

You can develop TMX to high density, but you need a scene with a high SBR. You can overexpose and overdevelop to get high density, but you get fog as lens/camera flare gets developed up into the mid-tone zones, not to mention chemical fogging.

I use reversal processed lithography (aka line or pre-press) film to make enlarged negatives for alt process. It produces a negative with lots of density and holds shadow detail.

I haven't tried using lith film in a camera but it should work - develop in dilute Dektol as used for reversal processing 1st developer. Lith film can be processed under red safelights making things a bit easier.

EI is probably in the range of ~3, I seem to remember reversal exposure times were comparable with paper.

I think enlarged negatives are the way to go for cyanotype/salt/van dyke prints. There also seems to be lots of folks using ink-jet prints to make enlarged negatives.

radiant · Oct 18, 2021

Nikola Dulgiarov said:
Mr Bill's reference to the family of curves is quite relevant, because it demonstrates graphically the tendencies as development time is increased.

Yes, that I'm familiar with. It doesn't however directly show underexposed behavior - but maybe we can look at the changes at the toe because that is the exposure dynamic range of the film when underexposing heavily. However that doesn't look that promising, at the toe area the density is not increasing as I would expect. The graph shows quite well that even a bit of more exposure from toe area makes huge leap in density.

I believe people are many times fooled of the heavy push performance when they do not realize how much scene SBR has to do with it. If your SBR is for example 5-7 stops, then your highlights get a decent amount of exposure and in longer development those gain density easily. Surely your shadows are blocked but then one might have shot such scene where shadows don't matter in terms of outlook.

I think true pushing capabilities should be measured with max 1-2 stop SBR. And measuring quality can also affect; I don't think many of us can constantly measure by ISO standards - so one might actually push only 1-2 stops by measurement error and get decent results because all of this. Of course you can do everything very sideways but then you can just explain "there must have been something wrong here"

I've done my own tests too but I don't want to post those because I don't want to guide this discussion to push processing itself. I am interested in how the film works and how much we can really squeeze out of B&W negative film. This is some sort of Dark Zone Theory I'm after here

radiant · Oct 18, 2021

Nicholas Lindan said:
I think enlarged negatives are the way to go for cyanotype/salt/van dyke prints. There also seems to be lots of folks using ink-jet prints to make enlarged negatives.

I'm not after huge density only. I'm interested how far can you develop an heavily underexposed parts of film (caused by underexposure).

I've been printing salt prints with UV enlarger now, I think that is really winner option for alt. But I am neither after negatives suitable for alt.processes in this topic

radiant · Oct 19, 2021

Sorry if I was being quite strict but I think the topics drift too easily.

RalphLambrecht · Oct 19, 2021

vedostuu said:
When developing B&W negative film and "pushing" the film, how much one can boost the density of the negative by development?

For example: you heavily underexpose the film and your "highlights" are just around the toe of the film. How much can you increase the density for these tones?

I made a test exposing HP5 at EI 6400 and developing in Xtol 1+1 for 45 minutes (30 sec agitation cycle). Maybe not a surprise but low SBR scenes came out very thin ..

Olea test can determine the precisely. Id photograph a Stouffer step wedge five times. Then develop them that for 5 1/2 8,11, and finally 16 minutes. Measure of the densities and extrapolate the curve.

radiant · Oct 19, 2021

RalphLambrecht said:
Olea test can determine the precisely. Id photograph a Stouffer step wedge five times. Then develop them that for 5 1/2 8,11, and finally 16 minutes. Measure of the densities and extrapolate the curve.

Yes, that I will do. I only have T2115 and it is a bit tricky to measure the correct exposure, but maybe shoot some "blank" frames against white with correct exposure.

radiant · Oct 19, 2021

michael_r said:
I’m still not sure I’m understanding what you’re looking for so if this post inadvertently drifts the topic feel free not to pursue it . However if you are interested, a while ago, as an experiment in maximum emulsion/shadow speed I “formulated” a developer specifically for the TMax films which extracted as much underexposed information as I think is possible. The principle was an ultra-low contrast developer that essentially linearizes the toe to the extent there is almost no toe.

Something else you can look into for extracting maximum toe detail is divided development, which also has a “linearizing” effect and can enable you to get as much real emulsion speed as possible without the excessive highlight densities associated with normal pushing.

Your experiment sounds interesting but it might not be what I want.

Maybe I put this way in this point: how much can I underexpose film while maintaining the darkroom printability. In what point I cannot in any means get grade 3 printable negative? I think this means what I've tried previously describe; to increase density in the highlights in way that we end up grade 3 negative.

I am not talking about normally exposed negative at all; this is about hard underexposure - as much as possible. But what is the limit? If my "highlight" is at Zone I or II, how far can I develop those without fog attacking my shadows?

RalphLambrecht · Oct 19, 2021

vedostuu said:
Yes, that I will do. I only have T2115 and it is a bit tricky to measure the correct exposure, but maybe shoot some "blank" frames against white with correct exposure.

That works in a pinch.

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