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It seems that many people are very eager to push their film. If you check sites such as Flickr or other communities discussing film photography, it can feel like almost as many people are shooting at a higher ISO and then pushing in development as there are using the box speed and standard development times, if not more. The websites of film producers and vendors boast about the ISO to which film can be pushed. Labs sometimes offer an option to push by one stop or even more while possibly no option for pulling is available.

What I'm wondering is, if push processing seems to deliver such desirable results, why wouldn't film just be rated at a higher ISO and its reference development times increased accordingly? Are the suggested speeds and dev times "safe" options that are the most likely to get a good exposure or sit in the comfortable middle of the film's latitude? Or is pushing simply popular to get the benefits of a higher film speed at the cost of image quality and with more potential risk for bad end results?

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    \$\begingroup\$ Push processing is over represented online because people who do push processing are more likely to have problems that require discussion to find solutions. They are also more likely to be generally enthusiastic about the process, so more likely to go online to discuss it. – Similarly for cross processing, alternative processing, pinhole photography, etc. They are all not that common, just over represented in discussions. \$\endgroup\$
    – xiota
    Dec 19, 2018 at 23:01
  • \$\begingroup\$ @xiota Excellent point. I had a feeling that there might have been some confirmation bias involved. \$\endgroup\$
    – G_H
    Dec 20, 2018 at 9:18
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    \$\begingroup\$ Also, not everyone discussing push processing actually does it often or at all. It's very much like smallpox. People still study it, and doctors could diagnose if they had to, but no one's actually seen a case since the late 1970s (despite claims otherwise). \$\endgroup\$
    – xiota
    Dec 20, 2018 at 11:32

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The optimal results using any film will be at ~box speed with standard development. I say ~box speed because even the box speed might be slightly off for a batch. In critical film work, one often buys film in bricks or batches so that a roll can be shot at varying ISO's, processed, and then the best ISO chosen for the rest (best being determined by film density). It's not uncommon to change the rating by 1/2 stop.

Pushing does come with tradeoffs and it would be silly to think otherwise. But, people like to be able to "get away" with things. If you can push a film +1 with only a very slight degradation in range and grain, then you've found a way to get faster shutter speeds when you need them.

Also, films react differently to the process, allowing one to experiment with "looks." As xiota notes in the comment, there are so many possible combinations that people discuss it at great length. The same is true on the opposite end if you search for Stand Development.

In my own experience in pushing 135 Ilford Delta 3200 to 1600, 3200, 6400, and 12800 and developing in DD-X...it looks like absolute garbage past 3200. I'm really not even a fan of it at 1600. But, shot in 120 at ISO 800 and souped in Rodinal...that I like. I mention this just to show that no, not all pushing gives desirable results. Also, if a lab is touting it, it's just to make more money off of you as they typically charge more for the process. If a film vendor touts it, take it with a grain of salt. Delta 3200 actual box speed is around 1200 but it's "meant to be pushed." I have found the results dissatisfying pushing to the "box speed" and using the recommended developer. YMMV.

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    \$\begingroup\$ Also, ISO is set according to a standard, and many development processes are standardized. If companies arbitrarily labeled films, it would defeat the purpose of having the standard. Pushing and pulling is intentionally going outside of those standards. \$\endgroup\$
    – xiota
    Dec 19, 2018 at 23:08
  • \$\begingroup\$ Outstanding answer. It's an interesting observation about people liking to "get away" with things. I could be mistaken, but got the impression that some people seem eager to jump onto push processing to make the process "their own" or feel like they're discovering something, rather than just following the manufacturer's recommendation. Maybe it's also related to some ISO ratings having been less available for a while. \$\endgroup\$
    – G_H
    Dec 20, 2018 at 9:27
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    \$\begingroup\$ @G_H thanks. That observation about getting away with things comes from high school for me where we all competed to get the best sports images of either the high school team on the terribly lit field at night or anything in the terribly lit gym. It became a point of pride to get away with a good shot having had to severely underexpose the film. \$\endgroup\$
    – OnBreak.
    Dec 20, 2018 at 14:49
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    \$\begingroup\$ It's a pedantic point, but remember that a film only has one ISO - it is measured by laboratory testing. When shooting the film at any other rating, you're using an EI (exposure index). So... Tri-X, an ISO 400 film, shot with a one-stop push, is shot at EI 800. (You'll notice a box of T-Max P3200 or Delta 3200 shows "EI 3200" on the box, because the laboratory ISO of each film is actually ISO 1000.) \$\endgroup\$
    – Jim MacKenzie
    Dec 20, 2018 at 19:38
  • \$\begingroup\$ @JimMacKenzie I don't think it's pedantic - it's a difference that should be understood by those pushing / pulling. Do you know what those laboratory tolerances are? As I stated, when actually testing a roll in a brick, I often ended up changing the ISO I used by a bit. The lab might design for ISO 400, so what's it mean when I test out a roll only to find I'll be shooting it at ISO 320? Was it at 400 at the lab and since changed or was the 1/3 stop within the testing tolerances? \$\endgroup\$
    – OnBreak.
    Dec 20, 2018 at 20:34

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