How much to push/pull : LUSENET : Large format photography : One Thread

When I was reading on sheet processing I found out the the best way to "bracked" is to take two exposures, process one, see how it looks and then process the second with push/pull to get a "perfect" exposure. All this sounds good, I did that, but the question is, how do you know how much to push or pull. Let say the first sheet is slightly too dark. I obviously want to push. How much? Can use use my spot meter somehow to meter the slide on the light box? For example, assuming I have a building in the shot and I want the wall A (dark) to look like wall B (not so dark), could I just meter both walls and push the processing with the difference?

-- Sorin Varzaru (, February 20, 2001



I believe that "to push" means to develop longer than normal. You state that if your first negative was too dark you would want to push. I would think that if you have a "too dark" (dense?) negative, then you would want to do one of two things, either develop less or expose less.

Don't forget, push processing has alot more influence on the high values (in the print, dense areas in the negative) whereas adequate exposure is critical for the low values (in the print, light areas in the negative).

May I suggest this. Do a test to determine your working ISO. that would be found by making exposures of a black card in shade and finding out which gives you .10 density of negative base plus fog. Once you find your working ISO you can then do some tests to determine development time for zones 7 and 8 so that you can match your negatives to your paper. Then, once you get all of that done, you can do a test to see for yourself how much push processing you would require to move a zone 6 up to a zone 7 or a zone 8 , etc. or pull processing to move a zone 8 down to a zone 7. You need to get a foot on a rock before you start trying to push and pull. Kevin

-- Kevin Kolosky (, February 20, 2001.

I appologise, I should've been more specific. I shoot color slide film exclusivly.

-- Sorin Varzaru (, February 20, 2001.

I think the E6 process does not allow this kind of flexibility. Most of these ideas are strictly for b&w film (Zone System N+1, N-2 etc). They're not push/pull in the normal sense (ie a whole stop like ASA400 to 800), but are minor adjustments to developing times to compress or expand the contrast range of the negative. I know you can push or pull E6 film, as most pro labs will do it (for an extra charge). Check the data sheet for the film.

-- Dave Mueller (, February 20, 2001.

It's so obvious English is not my first language. I can hardly make myself understood. I know how to push/pull E6. I know how to correct a half a stop or a full stop or any number of stops for that matter. What I don't know is how to evaluate (when looking at a slide) how much is was over/under exposed. So, I'm looking at the one that I developed at the nominal ISO, I somehow (and this is the "how to" question) determin how much was (let say) underexposed, then I process the second sheet accordingly.

-- Sorin Varzaru (, February 20, 2001.

I think this is old advice, and I agree that it applies more to B&W negatives than to trannies. Modern tranny films are very good indeed, and so are modern exposure meters. If you take an INCIDENT (not reflected reading)you should not need to bracket either your exposures or your development. I never do. Incidentally, a little while ago I had to push process Provia 100 by 2 stops. My processing lab said that this was O.K. and they were right - it did not block up and the colours were fine. Contrast was slightly up, but nothing to worry about. As I see it, in theory the answer to your question of how you judge the transparency is that the exposure is correct if, assuming you are viewing them on a light box, detail is visible in both the darkest bits that are not actually black and the lightest bits that are not actually white. As the level of illumination between lightboxes varies so much you have to assess this on your own lightbox. If you are printing from the tranny then the same criteria applies, although of course there is some adjustment possible at the printing stage. So much for the theory, in practice tranny films have a very limited range compared to black and white or even to colour neg., and you often simply can't get detail at both ends. You just have to choose which is more important! Your English is fine - I just hope you can understand my answer!

-- Garry Edwards (, February 20, 2001.

Your English is fine, I re-read your question, I did not read it correctly (my fault, not yours). Unfortunately, I think the answer is experience. The only way to develop a way to measure what you want is to run a series of tests where you change the development in small amounts (maybe 5 or 10%) and record the density changes. If E6 behaves like B&W, you'll need to have frames with several values on each one, since the shadows don't expand as much as highlights, and highlights don't compress as much as shadows.

-- Dave Mueller (, February 20, 2001.

In theory, it seems that the method you suggest could work. In practice, I don't know of anybody who does that. Maybe the problem is a spot meter would not measure an area small enough.

You end up by knowing how much you alter the processing of the second sheet by experience. What I suggest is that you ask the lab technician for his advice to begin. After you've seen the results a couple dozens of times, you'll be able to guess with good accuracy.

A few tips: (a) to begin stick with either 1/2 or 1/3 of stops. (b) To determine the amount of push, look at the highlight areas (they can be tiny, hence a meter would be of no help), and compare them with the average tone to see how much push they can take without washing out. Since you don't push beyond +1.5 stops (results in excessive contrast and murky shadows), all you have is to decide between a few values. (c) Be careful with pulling. Film is more sensitive to pulling than to pushing. The contrast is seriously reduced, and for optimal results, you will try to avoid pulling beyond -0.5 stops. Think about that when you are exposing.

-- Q.-Tuan Luong (, February 20, 2001.

It also seems that with your suggested method the readings would be dependent on the brightess of your lightbox, not to mention problems due to its possibly non-uniform illumination. It's surprising how much of that is compensated by the brain. I measured a difference of 2 fstops across my Logan, yet to the eye it looks sort of OK.

-- Q.-Tuan Luong (, February 20, 2001.

Tuan, shouldn't the difference between the area be independent of the light intensity ? Assuming of course the light is constant across the light table. And if it's not, I guess I could move the sheet to measure above the same area or the lt.

-- Sorin Varzaru (, February 20, 2001.

Sorin, are you running this film yourself, or are you using a lab? This is important because, as was stated above, your light box intensity/color balance is going to have to match up with whatever your lab's viewing area is as well. So, yes, it probably would be best to ask for their advice as to how much to push. I work in an in-house studio and we run our own E6, so yeah it's possible to push/pull in tiny increments to either tweak your exposures, contrast, or maybe use it to "clean" up highlights. You can get by with pushing E6 better than pulling, although you can reduce contrast this way. It's just that as you do this, you also effect color balance, so it can get tricky if you're after correct color. Light tables for correct viewing (like in a pro lab) are rated for CRI (color rendering index) this is alot different than just any light box, so what may look good on yours, may look lousy at the lab. I have worked in studios in the past, that did this sort of shooting all the time, but we usually try to center all our exposures around what's normal for us, and use a std. 1st dev. time. You can really fine tune it though, like 15 sec. extra might be all you need. Maybe use the highlights as your guide first, because if you push too far, they're going to be the first to go. If you're running your own E6, I might be able to get together some times for you. I've found that it's just more predictable to learn to use polaroid and base your exposures off that (judging highlights). I just reread your original post. I think the answer to your hypothetical bldg. shot is "no" (short answer). Because trans. only hold like 5 stops, so you might want to shoot on an overcast day, or expose for the lighter wall, and use a massive amount of fill for the shaded one. If you pushed your film, you might end up blowing out your highlights. Maybe someone could suggest the merits of pre-exposure as well. Oh well, sorry for the length, good luck..

-- DK Thompson (, February 20, 2001.


A good suggestion that has been made is that you need to learn (by your own experience and eyesight) what the differences in exposure will look like on E6. I'd like to suggest a way of learning this that will eliminate guesswork once you've learned what to look for. You can do this on a smaller format such as 35mm to save film costs. A longer series of test subjects will help you see the differences...

Try shooting a subject via your normal metering method. Let's say that you consider it mid-tone. Then bracket a half stop each way, and a full stop each way. You might even go further if you like. Then do the same thing with a light-toned subject, such as a snow-covered field, and bracket the same way. Finally, do the same with a darker than normal subject. You can expand this by covering a range of differently colored subjects too. It's not important whether your subject is a particular tone for this test, but you will easily be able to see the difference that various exposures make. For example, if your first exposure looks about a stop too dark compared to what you had in mind, you'll know to push the second exposure by a stop. Keep careful notes, and examine the results. Make sure that you can see each entire series at the same time, with the same illumination.

You should get a good idea of a half-stop from "ideal", a full stop from "ideal", and so on. This is basically the way that I learned how to spotmeter, and how to compensate accurately when metering a non- midtone subject. Good luck! Your English is very good, by the way :)

-- Danny Burk (, February 20, 2001.


I frequently ask my lab to push or pull Velvia and Ektachrome (E100S, E100SW, and so far only a little E100VS). Here are some of the things that I would suggest.

1. Don't worry about calibrating your light table and theirs. However, you must be consistent in your use. So always use your light table (assuming that you have a decent model), and change its bulbs before they get to the end of their lifespan. I think that my Graphic Light bulbs are rated for 3500 hours, but your brand may be different. Also try to consistently view your transparenies in the center of your light table when considering exposure.

2. You must always use the same lab, and they must run a carefully calibrated processing system. If your lab doesn't serve professionals, you may not achieve satisfactory results. I say "may not" because even some amateurs have sufficiently good technique to do this well.

3. I have used a spot meter to give me a starting point for estimating the correction. But I usually make 3 transparenies in situations in which I am unsure of the exposure or too rushed to be careful (i.e., light is fading). At any rate, make your reading on something close to mid-tone color. Having said this, I think that you'll also discover that two different exposures of the same subject may both be acceptable. This is particularly true of sunsets. Experience will improve your results.

4. I have pushed all of the above films up to 2 stops and pulled them up to 1 stop when I really wanted to see the image. These are extreme situations, and they don't always work out well. But sometimes I get usable results.

3. Finally, don't throw away the slightly under- or over-exposed images. They can be scanned for printing after correction in a photo-editing package. Or you can use them as the basis for making 70 mm duplicates for clients, thus saving your best originals for those who really want a 4x5 transparency.

By the way, I learned this procedure from Pat O'Hara several years ago.

Best wishes, Bruce

-- Bruce M. Herman (, February 20, 2001.

Thank you for all the advice you've given. For the record, I am shooting 8x10 color slide so I kind of have to keep the testing down due to the cost involved. I also do my own processing. Since I've started 8x10 a few weeks ago I only shot 7 pictures (14 exposures) and so far all my exposures were exactly as expected (no need for any of the above). That is probably due to the fact that handling a camera of this size really makes you measure twice before you "cut" :- ). I'm still working on my focusing though. I've managed to get the focus plane in the most bizare positions :-).

-- Sorin varzaru (, February 20, 2001.

I look at the extremes the highlights mostly to judge how much to push or pull. I know it isn't scientific but it works for me. If it looks like there is some grow there I might go a full stop on the push, or if I am very close to losing detail I want to retain, I stick to about a halp-stop push. Interestingly, it seems to me that an extra 1/3rd stop of exposure takes care of most of my needs to push film more than a half stop but it really depends on what the subject matter and the quality of the lighting is.

I made a very striking 4x5 image of Houston Mayor Lee Brown, a black man with very dark skin, that worked great on Velvia with a one-and-two-thirds push. The lower mid tones still had terrific depth and seperation while the mid tones "snap" and the white of his shirt is just below the "too much" threshold.

-- Ellis Vener (, February 21, 2001.


This is my preferred method for exposing color transparency when lighting remains consistent throughout the shoot. Until you gain some "intuitive" experience in evaluating and compensating exposure, I suggest you shoot at least 4 sheets of film, rather than 2...then you have extra sheets to test at compensated development times.

-- Tony Novak-Clifford (, February 21, 2001.

Sorin, somehow I had a feeling that you were running your own E6. So, how are you doing it for 8x10, in a rotary proc. or what? (really just curious) If you're using Kodak chem. I may be able to give you some first dev. times for pushing/pulling. But, and this is only a suggestion, if you're just starting out with all this, you may find it easier to learn how to make a "normal" exposure and bracket with your exposures, rather than doing it in the dev. I only say this, because with all the variables involved with E6, it seems to me the simpler you could keep things, the better off you'd be. (i.e. using a std. first dev. time). Just a thought, that's all. Good luck.

-- DK Thompson (, February 21, 2001.

DK, yes I am using a Jobo CPE-2 rotary processor. It's a bit of a pain since I can develop only one sheet at a time, but it's much faster then sending it to a lab and I have full control. Much cheaper too. I can use as little as 125ml of solution for 3 sheets. Although I usualy mix 150ml to be on the safe side. I do bracket when I'm using roll film (35mm and 120) but I came to realize bracketing (+/- hlaf a stop) and std development doesn't always work well. It happened quite a few times that I screwed up so bad while metering that the bracketed shots were bad too. Other times, I wish I had something in between the bracketed values. So, as soon as I figure out how to evaluate differences in exposure, I should be able to the the second sheet perfect. I use Tetenal 3 bath solutions. 6 + 1 STEPS is too much for me :-)

-- Sorin Varzaru (, February 21, 2001.

Sounds like you have your hands full. Sometimes we even have problems with our Wing Lynch machine here as far as staying in control (as they say). We run control strips and all that good stuff to keep our color good (on a 6 bath set up), so...that's kinda why I was suggesting to keep everything simple at first. I was just thinking that if you kept all your E6 stuff consistent, you wouldn't have to worry so much about film density if you were in a trouble-shooting mode. E6 thrives on doing everything the same way, every time. I still might be able to get you some times for the Tetenal stuff, although I suspect Jobo has these on their website. So, what do you do? Reuse the chemistry you mix up and just adjust the times to each succesive run, or are you doing this one-shot all the way? Another suggestion, and this might not be practical, would be to try to get a reducing back for your camera, so maybe you could use Polaroid film to get an idea of what you're doing. You could also use 8x10 polaroid, but talk about expensive...

-- DK Thompson (, February 21, 2001.

Sorin, I've been thinking a bit more about your question, and since nobody else is jumping in here, I thought I'd ask you to clarify a couple of things. Are you reusing this chemistry after each run? If so, are you adding anymore time to your first dev. to compenstae for this? By some rough calculations (I'm not a Jobo-person...), I think you may be losing like a 1/4 stop each time you reuse the dev. I also am not sure about this, but you probably need to use at least 150ml per sheet (again, I have never used a Jobo, so I can't say for sure, I'm looking at a Jobo book right now..) you might actually need more than that, it seems like a small amt. to me, especially if it has any chance of oxidizing in use...What sorts of speed problems did you have with roll film? Have you been able to have some confidence in your development, or were things all over the place? I'm really trying to help you here, but you need to nail down your E6 before you start messing around with pushing/pulling. Maybe you could shoot two sheets exactly the same way, take one to a good lab and have them do it, and you run the other. Then, at least you could compare the results. You might not have a metering problem, as much as a developing problem. Anyways, just trying to help, I'm sure there are some Jobo people on this forum who can help you better than I. Good luck.

-- DK Thompson (, February 22, 2001.

I am compensating for reuse (6:15 for 1st, 6:30 for 2nd and 6:45 for 3rd use) and they come out identical (150ml for a sheet). I do have the E6 pretty much under control. I've been doing it for a while (for 35 and 120) and aside from major screwups (when I made mistakes because I wasn't paying attention) I get consistent results. According to the chemistry manufacturer at least 160mm should be used for a sheet but I found out that the number is fairly conservative. Since my shooting is mostly experimental at this pount I don't particularily care about colors. If I did, I'd use more chemistry.

Those were exposure issues. I can tell because I had good exposures on the same roll.

Like I said before, my problem is not the processing, is evaluating how many stops or fraction of stops I need to push/ pull to get the "right" density.

-- Sorin Varzaru (, February 22, 2001.

Okay...hmm...I was going to ask if you had access to a densitometer, and have ever thought about running control strips, BUT, I'm not exactly sure how to answer your question. I think I understand what you're asking here, but I just don't know how to answer it. It may be a purely subjective thing, how it looks to you, not something written in stone. Let me think about this a bit, and discuss it with "the E6 guru" here...

-- DK Thompson (, February 22, 2001.

Sorin, here's something you can try, although it might use up several sheets of film, we were thinking what might help you would be to make a ringaround of different exposures. Like set up a nice evenly lit shot, where the light isn't going to be changing rapidly, and maybe include some good tones for reference. Like a gray card, a white, black, and maybe a specular highlight. Meter for a normal exposure and bracket in third stops up to +1 over, and -1. So, that'd be like 7 sheets total. Then run all this film, take good notes, be consistent. Now, you should have a visual reference for your process, and when you're looking at a CT on your light table, you can consult the ringaround as to which direction to go. This should also tell you just how consistent your E6 is as well. Of course, you could also do this with roll film, as someone else has already suggested earlier, but at least with the sheet film, it'd be what you were using anyway. To make it a little simpler at first, I'd suggest sticking to one kind of film. Hope this helps in some way.

-- DK Thompson (, February 22, 2001.

Be careful with your lightbox, I've found many of the new smaller items on the market are so bright they will make the slide looking brighter (also looking better because of good shadow detail) that is possible for good printing or reproduction results. As is earlier said, look for the highlights, there should always be some definition in them.

As I feel it, the E-6 process is standardized more for film speed than for good tonal result and natural reproduction. If you expose for only half of the film speed and develop for that (in a normal pro E-6 it means 5 minutes instead of 6 minutes) you'll achieve a larger exposure latitude and lower contrast. After getting accustomed with this you'll find a film developed "normally" very harsh and contrasty. I shoot myself only 8x10 slide film, making lightjets and cibas, and done this pulling for years. Couldn't never think of getting back to the standard developing scheme. For ten years I developed E-6 daily with big d-a-d machine as I owned a custom color lab and got from this work a lot of references over time.

-- Jan Eerala (, February 23, 2001.

Jan, in your experience, how much do you gain in latitude by pulling a stop? I like too shoot Astia. Speaking if Astia, anybody here knows what is it's latitude when processed normally. It seems to be a lot more then Velvia.
DK and everybody else, thank you for all your help. I'll let you know if I come up with a reproductibile procedure.

-- Sorin Varzaru (, February 23, 2001.

Sorin, I was starting to feel like I was interrogating you about your proc. techniques! Sorry about that, but for me E6 isn't exactly as enjoyable as b&w...I love running our own film in-house, while a set is still up and all that, but it can be a real pain sometimes.It seemed so much easier when we just sent out. I'm glad you asked that question about what Jan was saying because I was wondering about that myself. It sounds like the old b&w wisdom of exposing for the shadows, and dev. for the highlights. I've only shot Astia a couple of times, our main film is Provia 100. Compared to Velvia though, Astia should be a very neutral, low contrast film. I know you've said that you don't want to do much testing, and I understand why with film costs, but even if it's just shooting gray cards, this should give you someplace to you'll have the card in your hand for reference...

-- DK Thompson (, February 23, 2001.

If you half the film speed, you'll have to expose about one f-stop more. Because changes in development times have more effect on the highlights, the one f-stop will give about the same amount of light to the shadows. On the other hand, shorter developer time prevent highlights from beeing blocked, so there will also be more definition in the light end. When compared side by side the differences are so clear and logical, that I have never felt any need to measure the densities. There sure are differences between different films, but generalising, I'll say the exposure latitude expands with one and half to two stops.

Pulling E-6 is a critical thing, because if you do it even a little too much, you'll get a greenyellow colorshift. Often this shift can be better, because slide films generally creates some magenta when exposed in natural light. I am very critical with the colors in my own work, so I use most often a 81B filter (in rear of lens) with EPR- 64 film, which I prefer in outdoor use. I must also apologize for my limited english, but hope you got the main thing. Jan.

-- Jan Eerala (, February 23, 2001.

Jan, thanks. I may try that next time we shoot a contrasty scene. We routinely shoot things like old dark wooden washstands with marble tops...alot of flagging off lights. Maybe we can squeeze out a bit more latitude this way? So, you're just cutting back about a minute in the first dev. right? I guess the actual amount of that pull would rely on the type of chrome film you were shooting though. (Kodak vs. Fuji) We can figure out the color shift. We really only mess around with the densitometer if our color starts getting way off. As we're using a Wing-Lynch (one-shot) it's not like we have the same controls that you probably have in a tank line. Thanks for the tip, it might save the day for us sometime.

-- DK Thompson (, February 23, 2001.

DK you really should be running color control strips with your process and charting the results, at least daily if not with every run. I used to run a one shot E-6 process at the studio I apprenticed at (we used a Merz processor) and keeping a line that was in control was vital to superior processing and eliminating that that as a variable when odd color things would happen. It saved a lot of time.

Another tool you can use to reduce contrast are the Tiffen "Ultra Contrast" filters. These can lower the subject contrast without any obvious diffusion effect, but I don't advice that using them as a substitute for good lighting inthe first place. Still I'd rather use the UC filters than pull process E-6 or C-41.

-- Ellis Vener (, February 24, 2001.

Ellis, yeah I know that's a bad habit...we really don't have that much of a problem with control. It's frustrating in a way with a one-shot machine, because so much of your "control" is lost anyways. We have to occasionally correct the pH of certain solutions, and we're really meticulous with mixing, as far as no contamination (everything in it's mixing containers), and we check sp. grav. with hydrometers. We had the most problems, for about a year at least we seemed to be running about 5 pts. magenta, we were running plots daily, and were on the phone with Kodak/Fuji guys alot. We got it down finally to 2.5 pts., and then Kodak changed their chemistry to the new 1.5 liter kits (we have a 5 gal. Wing Lynch), and we get this chem. really cheap on a state contract. So, we had to retune it all to this new stuff. But actually it seems to be so much better. There are some new changes in the process (ha ha, don't you hate it when they do that?), so our card won't work exactly the same (we have to step over a wash between the color dev. and the pre-bleach!), but this new stuff runs really good. So, long story I guess (boring too), but we've gotten a bit lazy. The biggest problem we have now, is with our Intellifaucet, which has gotten real buggy...

I'll look into the filter. Both of us (2 photographers) did our prerequisite stint in the High Point furniture studios, so we do some fancy flagging of the lights with all sorts of home-made dots & fingers...but we shoot strobes instead of the hot lights you'd find over there. Some antiques can really suck up alot of light, it's amazing really. Thanks for the advice, I'll chastise my boss on Monday about the E6 proc. control!

-- DK Thompson (, February 24, 2001.

Ellis, Okay we ran our first control strip since last November today. My boss saw the little comment I made the other day so...anyways the strip came out almost perfect. The speed in the blue (LD) was a little off, but it was still within tolerance according to Kodak. The film's been looking great, so I guess we'll run more strips and see if this is a trend.

The problems were were having earlier were centered around the purity of the nitrogen we were using, the pH of the color dev. and a pre-wet on the machine. Once we got all this hammered out, our film has been looking real good. It is interesting that Kodak has reformulated their smaller E6 kits. Since they've eliminated formaldehyde from the stabilizer, they now skip the wash between the color dev. and the pre-bleach. I've talked to a few people who still run their Wing Lynch machines this way, but according to Kodak, the pH is very important of the color dev. carried over to the pre-bleach. They said it would affect the long term stability of the magenta in the film, and that the new final rinse is really close to just photo-flo... Is there anyone out there in this group who's running E6, especially in a Wing-Lynch??

-- DK Thompson (, February 27, 2001.

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