pushing film -- general confusion

[MelanieC]

Over the weekend, my research project had a booth at the Golden Gate Kennel Club dog show, held at the Cow Palace. I brought my Rolleiflex TLR with me because I thought it would be fun for dog photos and because it's a fun conversation starter. A reporter and photographer for the SF Weekly came to cover us (canine genetics merits at least a sidebar story, or so I understand), and I got into a conversation with the photographer when he asked me about my Rollei. He asked what film I had loaded in it and when I said "Tri-X" he asked me if I was going to push the film, since the light in the show venue pretty much sucked (at 2.8 my meter, which is accurate, wanted an average shutter speed of 1/30).

When I opened my mouth to answer, I realized that even though I had thought I understood what pushing film was, I really didn't. So I went online and did some reading.

If I understand correctly, the idea is to act as though the film is faster than it really is (exposing 400 at 800, for example) when taking photos, and then act as though it is slower than it really is (200 instead of 400) when developing it. Is that right?

If I understand correctly, the reason you do this is because overdeveloping will cause highlights to blow out, so you intentionally underexpose in order to give yourself more room to overdevelop. By this philosophy, you say goodbye to your shadow detail because you probably wouldn't have been able to get any anyway. Is that right?

I have a strong tendency to sort-of intentionally underexpose (in dim light, my meter might want 1/15 or 1/30 of a second, but I'll expose at 1/30 or 1/60 because I am worried about camera shake) and then develop the film normally for its rating and so far my results seem fine, or at least, they seem OK to me. Would adding a minute or so to development time be an acceptable substitute for pushing? (The way I look at it, it would be sloppy pushing?)

What I normally do is take my developer (I have only used D76 thus far), look at the tables in the film box, take the temperature of my chemicals, and develop like a robot exactly as prescribed. But, I am looking to branch out.

Nope, haven't developed that roll of 120 from the dog show yet. I know at least half of the frames are probably underexposed by a stop, but since I was using Tri-X I figure I'll be all right even developing the normal time.

 

[Simon Larbalestier]

If I understand correctly, the idea is to act as though the film is faster than it really is (exposing 400 at 800, for example) when taking photos, and then act as though it is slower than it really is (200 instead of 400) when developing it. Is that right?

If I understand correctly, the reason you do this is because overdeveloping will cause highlights to blow out, so you intentionally underexpose in order to give yourself more room to overdevelop. By this philosophy, you say goodbye to your shadow detail because you probably wouldn't have been able to get any anyway. Is that right?

Melanie there is an old saying that says "expose for the shadows and develop for the highlights" which is essentially what you are saying. You won't loose shadow detail if you factor that in when you take your meter reading at the higher ASA.

Tri-X like you say has a long exposure latitude so underexposing by 1 stop which = 800 ASA would still produce a very usable negative.

Sometimes it's a good idea to use a compensating developer (often two baths) to really control development of shadow detail and protect highlight detail.

 

[rich815]

Melanie there is an old saying that says "expose for the shadows and develop for the highlights" which is essentially what you are saying.

Agree with that, but when Melanie says:

"...in dim light, my meter might want 1/15 or 1/30 of a second, but I'll expose at 1/30 or 1/60 because I am worried about camera shake..."

She's actually underexposing by 1 stop (let alone exposing for the shadows) and likely losing all or most shadow detail with the result being bad grain and tone when she tries to compensate for the under-exposed neg in scanning or printing.

First, I'd recommend trying to shoot more at 1/15th. With the TLRs I have had great success down to that slow in a pinch, especially if you use at least a neck strap and brace the camera strap down against the back of your neck.

You could push (which IMO way too many people are too quick to do) but you will fast lose some of the best attributes of good B&W film such as smooth tonality, good shadow detail and detailed sharpness. If you find that yo uare having to shoot too much under 1/30th or 1/15th then consider another film like Neopan 1600 or Delta 3200 (which I shoot at 1000). But in a pinch Tri-X should push pretty well at least one stop.

 

[dnk512]

I am editing me previous quick responce because it was wrong. Hope this is better:

When you push you sacrifice shadows but get to use higher shutter speeds (to freeze subject motion). Then, you overdevelope to try to re-claim some of the underexposed mid greys but you also blow over your highlights. So, with the darks very dark and the brights very bright you get higher overall contrast and loss of detail on both ends (brights and darks)... But you get to use faster speeds.

 

[MadMan2k]

Well, pushing is just pretending it's a faster film in shooting and developing, as far as I know. Pulling would be the opposite.

 

[sigma4ever]

Well, my understanding just got 70% better. Thank you MelanieC. I am currently pushing some b&w 400 to 800 and will hopefully develop soon. It will be interesting to see how they come out. Just to make sure, when developing film that has been pushed by one stop, you should overdevelop by a little to increase the detail that was lost when shooting? (opposing veiws from everybody!) Just lay it on the line for me please.

 

[MikeL]

I've been happy underexposing HP5 (taking image at 800 rather than 400) and then overdeveloping (develop for an additional 2min over the 400 times). Melanie, I think that's what you're looking to do?

 

[MikeL]

Here's info from the Ilford site-Pushing

 

[MelanieC]

Thanks for the info, guys. I have to admit that the expression "expose for the shadows, develop for the highlights" still confuses me, but I guess I'll figure it out sooner or later.

I managed to dig up the processing manual for D76 on Kodak's website. It says: "Use the development times in the table below to process roll films exposed at speeds higher than their normal ISO or EI ratings. When you expose the film listed in the table at a speed 1stop faster than the rated speed, we recommend that you develop them for the normal time. The underexposure latitude of these films is wide enough to give you good results with finer grain than you would obtain with push processing."

So I guess for my normal low-light shooting I'm OK with just using the normal development times like I thought.

 

[Simon Larbalestier]

My understanding is a bit different. Overdevelopment will not affect your highlights, but, help your shadows. So when you push you sacrifice shadows but use higher shutter speed to freeze subject motion. Then, you overdevelope to try to re-claim some of the underexposed shadows.

Fromm my experience, this very much depends on the type of developer you use - generally increasing development time will increase contrast therefore compressing the tonal scale so the highlights will tend to clog and shadow detail is reduced.

Developers like Microphen and Ilford's DXX are designed for pushing films 2-3 stops past their usual designated ISO without increasing contrast and increasing grain too much.

Shadow detail is preserved by placing your darkest shadow value on a zone of 2 or 3
yet you must make sure your hightlights aren't placed on too high a zone i'd say 8+ is max if your printing on conventional multigrade fibre papers.

Adjusting development time, temperature and type of developer can fine tune this to allow for better development at both ends of the tonal scale. This is more noticable in 120 and sheet film than in 35mm films. This method has always worked for me.

 

[planetjoe]

As I understand it, Melanie, you've got it about right. However, the general opinion on the meaning of a "push" leans toward two inextricably linked components:

1. intentional underexposure by x stops (i.e., "rating the film at higher EI")
2. intentional overdevelopment by x stops

Note that this practice isn't designed, I think, to get more film speed "for free", but rather to capture a reasonable range of shadow detail at low EI. I could be wrong about that last bit, though - but the process does carry an unavoidable penalty, if you consider it as such, of high contrast in the processed negative. Sometimes, I think, this isn't a bad thing, but YMMV.

I've actually been trying to reconcile Zone exposure control with "pushing", which led me to this very old post over on pnet. Perhaps you'll find it interesting.

I think the point is to achieve what is suggested, e.g. "expose for the shadows and develop for the highlights" - which I think sounds like a very Ansel Adams thing to say - even though I've never exactly understood what that really means.

I also think that Simon states a very popular practice (rightfully so) in his advice to use a compensating developer. Diafine (probably the most popular two-bath dev around these parts) will supposedly handle pushing like a champ, with certain limitations. Search RFF and you'll see LOTS of info.

As for pushing with D76, which I'm actually about to do (Tri-X pushed to 3200 (!)), my understanding so far is to follow the directions on the "box" (or the massive dev chart on digitaltruth.com) for push-development. Cut-and-dry, so to speak; pun intended.

Oh, well, I guess we'll see. Please post your results, and have a good time.


Cheers,
--joe.

 

[planetjoe]

Shadow detail is preserved by placing your darkest shadow value on a zone of 2 or 3
yet you must make sure your hightlights aren't placed on too high a zone i'd say 8+ is max if your printing on conventional multigrade fibre papers.

Ah - that's exactly the bit I didn't quite get. Now it makes sense that one would normally sacrifice highlight detail in the high-contrast negative. I couldn't get that straight; originally I was thinking, "hmm, if I place middle gray on Zone 2..." but of course that was precisely backward. Thanks, Simon.

Now that I think of it, pushing really "hurts" (depending on your developer) because negative density is logarithmic, isn't it? The curve gets so steep that you lose highlights quicker than you can recover shadow detail.

Or, something like that. Bah; it's too late for thinking.


Cheers,
--joe.

 

[MelanieC]

I guess now would be a good time to finally read up on the Zone system like I keep meaning to do. Thanks for the info, Simon!

 

[Simon Larbalestier]

I think the point is to achieve what is suggested, e.g. "expose for the shadows and develop for the highlights" - which I think sounds like a very Ansel Adams thing to say - even though I've never exactly understood what that really means. Cheers,
--joe.

I think it was Fred Picker who started the famous Zone VI brand of excellent darkroom gear who said this or maybe it was Ansel Adams in his book the Negative. Fred Picker's book (which i can't remember the title of as it's back in the UK) simplifies the zone system for 35mm and 120 films. Well worth a read.

 

[kaiyen]

Man, this is a weird thread. I don't mean that to disparage anyone at all. It just seems to have moved in several directions at once. I am not an expert on...anything. But I generally have tried just about everything (except Pyro developers and Diafine) in the darkroom, and I tend to hang out in here, so I post when I can 🙂.

First off, pushing has nothing to do with exposure. It is, however, a relationship. First, you underexpose. That's just plain old underexposure. This sacrifices shadow detail to begin with. Right off the bat, shadow detail has been compromised. The idea of "expose for the shadows" or the various comments by White, Adams, and the BTZS folks don't count anymore, other than knowing that your shadows are gone. This is just general talk - you can mitigate this somewhat with your developer choice.

Pushing is actually during the processing step. It is when you extend development time. Technically speaking, the simple definition is that you are extending development and sacrificing highlights in order to pull your midtones into an acceptable range. Remember that shadow details are basically gone already, so it's the highlights and, by extension, the midtones that get involved here.

Therefore:

If I understand correctly, the reason you do this is because overdeveloping will cause highlights to blow out, so you intentionally underexpose in order to give yourself more room to overdevelop. By this philosophy, you say goodbye to your shadow detail because you probably wouldn't have been able to get any anyway. Is that right?

No, unfortunately that is not correct. You are not giving yourself extra room. You are merely underexposing. You do that primarily because you are forced to do so (not enough light) or because you're going after a look. Looking it as you are above is kind of backwards. You don't underexpose to allow you to develop longer. You develop longer to compensate for the underexposure.

Melanie there is an old saying that says "expose for the shadows and develop for the highlights" which is essentially what you are saying. You won't loose shadow detail if you factor that in when you take your meter reading at the higher ASA.

Not true. If TXT is a 400 speed in your developer (note that I am recognizing that you get different speeds based on developer), then metering the shadows at EI, say, 800 or 1600 won't magically give you shadow details. You are _still_ underexposing and sacrificing shadow details. Even without factoring in the toe, which is a non-linear relationship between exposure and increase in shadow density in the low-light areas of the curve, you are giving 1 to 2 stops less light to the film. Metering for the shadows in this situation just means you are more accurately underexposing 🙂. But the shadows are still gone. The film just isn't that fast.

My understanding is a bit different. Overdevelopment will not affect your highlights, but, help your shadows. So when you push you sacrifice shadows but use higher shutter speed to freeze subject motion. Then, you overdevelope to try to re-claim some of the underexposed shadows.

Development always affects the highlights. Period. Now, technically, with modern emulsions (current ones, not the t/e-grain ones), the shadows will pull up a bit with overdevelopment, but not as much as the highlights or midtones. You overdevelop to bring the midtones back. Shadows are lost and gone forever.

Well, pushing is just pretending it's a faster film in shooting and developing, as far as I know. Pulling would be the opposite.

I think "pretending" is a bit strong of a word. Pushing film, as a complete process, is the act of intentionally underexposing film in order to get the shutter speeds you need in order to get the shot (as compared to just not shooting at all...) and compensating (ie - extending) development proportionally to get the best result possible. Pulling is compensating for overexposure, usually meant to increase shadow detail and/or decrease contrast (kind of the same thing). Again, it's a complete process - you overexpose, which is a step unto itself. You haven't pulled until you use decreased development to control the highlights and keep midtones where they are supposed to be.

Just to make sure, when developing film that has been pushed by one stop, you should overdevelop by a little to increase the detail that was lost when shooting?

Stay focused, everyone! "Detail" is too vague of a word. Shadow detail is gone or significantly compromised by underexposure. You develop a little longer to bring back midtone details while sacrificing the highlight detail.

Note that this practice isn't designed, I think, to get more film speed "for free", but rather to capture a reasonable range of shadow detail at low EI

You cannot get more film speed ever. If it's 400 in developer A, then it is 400. If it's 540 in another developer, or 200 in another one, then those are the film speeds in those developers. Period. Pushing film is designed to give you a higher shutter speed or user a smaller aperture.

I think the point is to achieve what is suggested, e.g. "expose for the shadows and develop for the highlights" - which I think sounds like a very Ansel Adams thing to say - even though I've never exactly understood what that really means.

Again, this adage gets thrown out when pushing. If the idea is to expose for the shadows, then you wouldn't be underexposing in the first place. However, what it tells you is that shadow detail is controlled by exposure, and that by underexposing you have compromised shadow detail significantly. That's what it means in this context.

The only but rather major caveat to all this, and one to which I think I have alluded already, is that developer choice plays a signifant role. First, some developers will give you more speed right off the bat. Microphen gives me about 540 for TXT, for instance. That helps - I'm not pushing as much when I shoot at 800 or 1600. Microphen is also good for pushing, as it is a low fog, low contrast developer. I shoot TXT at 1600 (1.6 push) and develop for 16 minutes and it's still got controlled highlights with excellent midtones. I could probably go to 20 and the highlights still wouldn't be too far out there.

Technique comes into play, as well, as others have also mentioned. Higher dilution with less agitation (compensation, which happens with _all_ developers with this technique) will increase shadow detail while controlling highlight detail. BUT - if you underexpose by, say, 3 stops, no amount of compensation will save that. Or, just in case merciful's 12800 EI TXT example comes up, no amount of compensation will bring back the amount of shadow detail that you would've had at 400 or whatever your developer gives you.

Okay. That was a long post. I hope it made some sense.

allan

 

[telenous]

there is an old saying that says "expose for the shadows and develop for the highlights" QUOTE]

Simon, that old saying confuses me too. The way I read it, it means that you should (over?)expose the frame in order to capture as much shadow detail as possible, and then (under?)develop so that you tame the highlights back to zone 8. Effectively that amounts to pulling! But it obviously is meant to say the converse if whoever said it first offered it as an advice to pushing. I am trying to see if there is some ambiguity in it, so that it can have the converse meaning, but I fail to see it 😕 I guess I may be missing something.

Anyway, like others here, when I push the film I essentially underexpose it one stop and then compensate in (extending) developing time. Depending on the film/developer I use, the process is more or less succesful. In my limited experience HP5 and TriX push well, T-grain films don't. From the developer side of the equation DDX and Microphen are good push developers, Rodinal less so.

I have found it useful to bear in mind an advice that I was given some time ago in this very forum: a pushed film is essentially underexposed and overdeveloped. You do not get the extra speed out of the film and that is why you lose shadow detail. With a fast developer like Microphen you are starting better off by regaining about 2/3 of the speed, without going overly contrasty.

 

[kaiyen]

The way I read it, it means that you should (over?)expose the frame in order to capture as much shadow detail as possible, and then (under?)develop so that you tame the highlights back to zone 8

No, it means that you should expose properly, based on your EI, then close down by 2 stops, to get the proper shadow detail. Shadow detail is in zone III, remember.

allan

 

[Simon Larbalestier]

Man, this is a weird thread. I don't mean that to disparage anyone at all.

really? it sounds like it to me.

Not true. If TXT is a 400 speed in your developer (note that I am recognizing that you get different speeds based on developer), then metering the shadows at EI, say, 800 or 1600 won't magically give you shadow details. You are _still_ underexposing and sacrificing shadow details. Even without factoring in the toe, which is a non-linear relationship between exposure and increase in shadow density in the low-light areas of the curve, you are giving 1 to 2 stops less light to the film. Metering for the shadows in this situation just means you are more accurately underexposing 🙂. But the shadows are still gone. The film just isn't that fast.

I don't see it this way at all not when you place the readings on a zone scale but then i chose to follow Fred Pickard's method of metering and then adapted this to work with the Pyro developers so i'm able to get good shadow detail and good highlights at speeds between 400 and 1600 ASA which suits my particular way of working.



[/QUOTE]The only but rather major caveat to all this, and one to which I think I have alluded already, is that developer choice plays a signifant role.

allan[/QUOTE]

This is the only point you've made that makes any sense to me.

Still we all reach our results in different ways and utimatley we choose the pathway that works best for us. So it is quite natural for there to be offered different ways of working when responding to a thread like this 🙂

 

[vicmortelmans]

Interesting discussion. I went through the process of trying to understand pushing a while ago, so maybe this is a good opportunity to cross-check my findings.

If you know about a film's characteristic curve mapping density to exposure, it's quite easy to visualize. The curve has a toe at the shadow-end and a shoulder at the highlight-end. You must imagine that someone's standing on the curve's toe, so it can't move (that 'someone' is your choice of developer). You can however move the curve by changing development time. Increasing development will make it steeper (N+1, N+2). Because the curve has a maximum (the maximum density of the film), the shoulder will not lift, but rather move the left side when increasing development, thus also making the area between toe and shoulder smaller (this is the increased contrast).

I've made some graphs on this, which can help:

http://users.pandora.be/vicmortelmans/fts/development/index.html

Groeten,

Vic

 

[Pherdinand]

Melanie - how about "sacrificing" a roll or two, and testing it for yourself. These things depend on a lot of details incl. HOW you do the developing (how you measure the time, how often and how strong you shake the soup etc) so the results of other people can work only so-so for you.
Certainly, underexposing a BW neg and developing as normal should result in thinner negative (less dark) but not necessarily worse; especially, that scanning film goes better with thin negatives.

OTOH, be sure to try a very fast film for comparison, like the delta 3200 in your Rolleiflex will look great.