Pushing film that was exposed in sufficient light and at night?

[andrew_kenefick]

I've been reading a lot of the pushing threads lately, and I have

not, as of yet, pushed a roll of film.

My question is this:

Say you have a 24 exposure roll of film, and you go out and take 12

shots in the daytime in good light, and then you go out at night,

bump the EI rating up a considerable amount, and take the last 12

shots with the intention of pushing the film. When you actually

develop the film, how do you do it? If you develop long enough for

the night pictures to come out, won't it hurt the quality of the

shots taken in the daytime?<br>

Please help and thank you,<br>

Andrew

[stephen hazelton]

You take the whole roll at the same EI. If you DO wind up with a roll of film like that, figure out which half is more important,and develop for it, figuring to ruin the other half. You could cut the film in half in the darkroom and lose a few frames one way or the other ....IF you didn't get the ends mixed up and ruin it all!

[pete_gee]

Im sure someone will give a proper explanation, but you have to shoot the whole roll at the same rating (ie film marked as 400, with your camera set to 400, or 800 1 stop push, or 1600 2 stops pushed etc).

Film gets given an ASA rating, based on the recomended development - ie you follow the recommended development and expose it at the rated ASA then you will get (should get) correctly exposed negatives. IF you change one of the variables, you need to compensate by changing the other to make up for it. eg, you put a 400 ASA speed film in your camera and set the ASA setting on your camera to 800, you will be under-exposing it by 1 stop, so you need to compensate by increasing development time to get back the 'properly exposed' negative - but the contrast will change.

 

So as a direct answer to your question, one half will either come out too dense, and the other half correct, OR, one half too thin, the other half correct. Maybe you try for a compromise between the two? but neither half will be all that good.

 

I think going for the Dense & normal combination would be better than the normal/thin combination.

[nige_buddy]

Ideally, you take the roll out, put another roll in and use that. You can then use the rest of the 1st roll in more suitable conditions if you remmeber to write how many exposures have been used, leave the leader out or have a leader extraction tool handy.

[m0002a]

Pushing film adds more contrast (always) and more grain (usually). This may be necessary, and even somewhat desirable, in dim lighting when more speed and more contrast are needed. It will probably make your shots in the daylight a bit worse than otherwise would be the case (unless it was a very overcast day).

 

Adjusting the exposure and development to accommodate each particular situation is what the Zone System is mostly about. Ironically, the anti-Zoners are the ones who push the most often. But the anti-Zoners are right about one thing--you can't use the Zone System if the lighting conditions are not generally the same on the entire roll.

[doremus_scudder1]

Andrew, and all,

 

There is so much misinformation about "pushing" going around lately, and, since I'm home with a cold today and have some time to kill, maybe I can help the general misinformation by providing a more accurate and detailed discussion of the subject. This is long, but worth it if you don't know it already.

 

Firstly, the term "push" as it is commonly understood is a simplification. Many photographers understand it as "make my film faster by setting the ISO dial to a higher number and then develop a long time and, voila, great available light pics!".

This is useful and convenient in many cases in practice, but an more thorough understanding will help use "pushing" wisely and insure better results and less wasted time. So, here goes. A primer for potential pushers:

 

"Pushing" is used to describe a technique to get usable images from intentionally (or occasionally unintentionally) underexposed film. The situation that usually requires "pushing" is trying to photograph in inadequate light to make an acceptable normal exposure (either too dark, subjects moving to fast, or a combination of the two. In all cases, the desired aperture/shutter speed combination won't give enough light to expose the film properly). One then simply makes the photos at the desired aperture/shutter combination and attempts to compensate for the resulting underexposure of the film by increasing development time, changing developer, or a combination of the two.

 

"Pushing" consists, then, of two elements. Underexposure and Overdevelopment. It is helpful to examine these elements individually to understand better just what their effects on the final image will be.

 

First, let's look at underexposure. Imagine a subject that like an evenly-lit sheet, that has only one brightness level. By varying the exposure, one can vary the value of this one-tone subject in the negative: More exposure, the subject will be more dense on the negative; less exposure, it will be less dense on the negative. As we give less and less exposure, a point will be reached where there is no image on the negative at all. In other words, a there is a point for every film where a given exposure equals NO exposure. The dividing line between the exposure that gives no density and one that gives a little density is called the threshold of the film.

Generally speaking, any exposure below the effective threshold of the film will result in NO image at all, regardless of developer or developing time. This will be important later. (This too, is a bit of an oversimplification, since there are some developers that increase true film speed a little, but accurate enough for understanding the principles.)

 

Normal scenes contain many different brightness levels. Scenes that require "pushing", in addition to having a generally low average light level, often have an even greater range of brightness levels than normal ones, i.e. some very bright areas (usually light sources or reflections of them) and some extremely dark areas (shadows under cars at night, for example). This means that intentionally underexposing such a scene results in significant portions of it being below the threshold of the film. We know now that this means that these below-the-threshold portions will be completely without image on the negative, i.e. totally clear. These are usually the "shadow values", but, depending on the amount of underexposure, could contain some "lower mid-tone values as well.

 

But, what about the other areas, how will they be rendered on the negative? First, lets look at the areas just above the threshold. Since so much of the shadow values have been exposed below the threshold, these would normally correspond to mid-tones. These values, by definition, are exposed just barely above where the film starts to record image information and, due to characteristics of the film are not recorded with much difference in density. In other words, these "low values" on the neg (which are really our mid-tones) have reduced separation compared to what they would have had they received more exposure. This is always true for low values on negatives. With a fully exposed negative, however, this information is usually less important to the final image since it is only the very darkest shadow values. In the case of "pushing" we now have our important mid-tones sitting here in this less-than-desirable spot on the negative scale. The high values are usually equally underexposed (except for bright light sources and reflections) but have relatively more separation on the negative since they, at least, are somewhere in the middle of the negative scale.

 

So, to summarize, underexposing gives us shadow values that are so underexposed that they do not appear on the film at all and mid-tones that make only a small density on the film and suffer from lack of separation. If we developed this negative normally and made a print we would find that if the clear areas of the negative were rendered black in the print, the mid-tones would be very very dark and the highlights would be like middle grays. If we printed to make the highlights white, there would be no black in the print. What can we do to alter this distribution of tones?

 

We overdevelop the negative! Overdeveloping does two related things. The first we are all familiar with: The more development, the more density on the negative for a given exposure. In the case of our example, this moves the high values up toward where they would normally be on a properly exposed negative. The second related effect has to do with the fact that the increase in density from overdevelopment is proportional. That means, a given amount of overdevelopment will effect the higher densities in the negative more than the lower ones. While this means that our poor, underexposed mid-tones will not be increased in density by as much as the higher values, it also means that the difference between these two values will increase. In other words, the density range (read contrast range) in the negative will increase. Overdeveloping then, can help our underexposed negative by: A) giving the negative more overall density and, B) stretching out the density range of the negative by increasing the separation between lower and higher densities (this is normally thought of as increased contrast).

 

The gratifying results of overdevelopment then are that the mid-tones have a little more density and separation on the negative and higher tones are even more expanded (this can also be bad). Printing this negative so that the clear areas of the negative are black will usually give a much more acceptable print. There are, however a lot of disadvantages to overdeveloping as well. Overdeveloping increases contrast: While this is alright if you need to increase contrast, most scenes that require "pushing" do not. Another side-effect of longer development times is increased grain.

 

Let us examine then, what we can expect from "pushing": First, keep in mind that all those areas that were exposed below the threshold of the film will be completely blank on the negative and have no detail whatsoever in the final print. That information is lost and gone forever. Most usually print these areas as pure black. The remaining information on the negative will have markedly increased contrast overall, but the mid-tone areas, which were exposed on the toe of the film, can still suffer from a lack of separation. High values can be overly contrasty. If the original scene was very contrasty, then we have done nothing but increase this contrast in the high areas even more by increasing the development time. A print from an underexposed negative that has a good range of tones from black to white may very well be unpleasantly too contrasty and harsh while at the same time having muddy mid-tones and no shadow detail. This can be a printing nightmare and it may be impossible to make an acceptable final print at all from such a negative. Finally, a print from an overdeveloped negative will show more grain. This may also be unpleasant. Some like the look of grainy prints, others prefer smoother grainless prints. This boils down to an aesthetic question

 

Finally, let's take a look at some of the misconceptions and lingo that go with "pushing" and clarify them a bit. First and foremost, "pushing" does not increase film speed (some developers, like Microphen, WILL give slightly higher film speeds. This true increase in film speed is rarely even a stop and does not qualify as "pushing" as defined as "underexposure and overdevelopment"). Photographers talk about "pushing one stop" or "shooting Tri-X at ISO 1600". This simply tells us by how much the film has been underexposed. Remember, we can't really speed up film by "pushing". We simply increase contrast and density to try to obtain a more printable negative. One also hears "I shoot HP-5 and 6400 all the time". Yes, one can set their exposure meter to 6400 and make exposures, but we should be aware that the higher one rates a given film, the more of the low values in the scene are lost, being exposed under the threshold, and the more overdevelopment will be required to render any kind of image on the negative at all. Pushing 5 stops roughly results in the bottom half of the values in a given scene being exposed below the threshold, leaving only the top half (i.e. the brightest values) for us to make a print from. This is acceptable only if one is willing to live with LOTS of contrast, grain and lost information. Most of us aren't. Lastly, the term "pushing" itself is somehow deceptive. If we understand it as "underexposure and overdevelopment, then fine, but in reality all we are "pushing" are the limits of the medium: we "push" information out of the negative on the low end, "push" the contrast up too much on the high end and "push" the grain up to maximum size.

 

In closing, it is interesting to note that Zone System photographers never speak of "pushing". They (myself included) expose to get as much shadow detail up on to the straight-line portion of the film curve as possible and develop to achieve an "ideal" contrast range. Overdevelopment is a tool for increasing contrast only. True, we "Zonies" don't spend a lot of time taking available-light photos; the goals being usually smooth-grained prints with lots of shadow detail and tonal gradation. However when confronted with a low-light situation and the possibility of a meaningful photograph, Zone System photographers will "push" along with the best. What Zone System practitioners and the best "pushers" usually realize, however, is exactly what to expect from the combined effects of underexposure and overdevelopment. I hope this more detailed treatment of the topic helps those of you in the beginning stages of the photographic journey to better understand what is known as "pushing" and, therefore, help save you time, effort and, most importantly, come away with better images.

 

Regards,

 

[phule]

Doremus,

 

If this is what we're blessed with when you get sick, I think you should go out into the cold without a coat on more often! :)

[mike_scarpitti]

Andrew, there is little to add to what Doremus has written. Don't push. It's a foolish pastime. If it's too dark to take pictures, let it go. Learn to accept the world as it is: imperfect. Make good pictures, and if that's not possible, don't bother.

[andrew_kenefick]

Doremus,<br>

That was the most thorough explanation I have been able to find on the internet regarding this topic.<br>

Thank you and everyone for their responses,<br>

Andrew

[roger krueger]

Doremus: Thanks immensely for a clear, concise explanation.

 

There are some other issues I would raise, however.

 

First his explanation assumes you stay with normal "straight-line" development. Compensating development, using dilute developers with limited agitation, can boost your midtones, and to a limited extent, your shadows, while controlling runaway highlight contrast.

 

It does this by relying on the developer becoming locally exhausted in the highlight areas, stopping or slowing development there, while continuing development in less dense areas. I've found this to give much better push results than simply doing normal development for a longer time.

 

The downside is that limited agitation can give strange results on high-contrast edges, and can cause streaking with some films. I've also seen reports that would lead me to believe limited agitation doesn't work well with "swizzle stick" agitation.

 

In most cases film records a great deal of shadow detail that never actually shows up in the final neg. This is because the anti-fog chemicals that help keep the developer from developing completely unexposed silver also impair the ability to develop slightly exposed silver. In normal circumstances this is a good trade-off, because the more fog, or base density you have, the longer it takes to print. In a normally-exposed negative there are few or no areas that fall into this slightly exposed category.

 

But in a pushed neg, you need all that info. Mike Maunder at Speedibrews in the UK has come up with a speed developer that apparently concedes quite high base density to deliver high speed with shadow detail and modest contrast. Getting delivery to the U.S. is problematic, however, but I'm hoping to receive my first packet in the next couple of weeks.

 

Different films deal with this issue of barely-exposed shadow detail differently too. I've found that sufficiently extended development can get very, very nearly as much shadow detail out of TMY as out of Delta 3200/TMZ, even though it's over a stop slower. The faster films make it much simpler to control runaway highlights, but don't really improve the shadow situation that much.

 

Another biggy in a push situation is the need to develop immediately. Just barely exposed shadow detail tends to fade as the exposed roll sits undeveloped.

 

If you add format into the equation, pushing can yield LESS grain--say I meter a scene at 1/60 at f1.4 and EI400. That's wide-open for the fastest lens I can afford. Now if I move to my 6x9, my fastest lens is an f2.8, I need a 2-stop push to keep the 1/60th shutter speed. But the reduced enlargement needed yields a print with much less grain, and sharpness that rivals 100-speed 35mm.

[lex_jenkins]

<i>"True, we "Zonies" don't spend a lot of time taking available-light photos...However when confronted with a low-light situation and the possibility of a meaningful photograph, Zone System photographers will "push" along with the best."</i><p>

 

That's what I thought. ;><p>

 

There appear to be differences of opinion over what constitutes "a meaningful photograph."<p>

 

For some, the subject matter determines whether a photo is worth making. Exposure and processing may then be adjusted as needed.<p>

 

For others, if any deviation from correct exposure and processing is required then *no* subject matter of any kind is worth a single frame.<p>

 

To me the latter seems to me an unnecessary stricture. However, to each his or her own.<p>

 

Which is the only point I absolutely insist on here: To each his or her own.<p>

[doremus_scudder1]

Roger,

 

Thanks for filling in the some of the blanks in my "primer". I'm sure there are many more as well, since photochemistry is much more intresting, mysterious and complicated than the simplifications we use to try and understand it. If I were still doing theater photography, I'd be standing in line to try that new developer!

 

This has become one of the more interesting threads on this forum in a while.

 

Regards,