What is push pull in film?

[leicatwins]

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Hi, I am still learning about film photography. I read somewhere about "push" and "pull" of ISO of certain film. What does it effect? Why people do it? I know my friend likes to use an ISO different from the actual one.

 

Thanks for any share of knowledge.

Difi

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[rubenkok]

Hi Difi,

Maybe this is some help:

Push processing - Wikipedia, the free encyclopedia

All the best

Ruben

[leicatwins]

Thanks Ruben

[Kent10D]

As the Wikipedia entry that Ruben linked to says, photographers push film when they need a higher speed for low light work or so they can use a shorter exposure to stop fast action. It also produces a more contrasty look, if that's what you want for artistic purposes. "Pushing" the film implies underexposing it, and then over-developing it to compensate.

 

The reasons for pulling the film are obviously going to be different. When you "pull" a film you're essentially overexposing it, and then under-developing it to compensate. This has the effect of bringing out more shadow detail than you'd get with normal exposure, sometimes at the expense of highlight detail. Quite a few film shooters pull Tri-X, treating it as an ISO 200 film. This results in a tonal range that some people prefer.

 

Lots of room for experimentation ... which is part of the fun of using film.

[innerimager]

When applying this to chromogenic B&W- When folks use XP2 and set it at ISo 200 in camera rather than 400, do they then ask the lab to develop it at Iso 200? When I set it at 200 I have been developing normally and basically getting a +1EV exposure compensation. Thanks...Peter

[Michael Hiles]

When applying this to chromogenic B&W- When folks use XP2 and set it at ISo 200 in camera rather than 400, do they then ask the lab to develop it at Iso 200? When I set it at 200 I have been developing normally and basically getting a +1EV exposure compensation. Thanks...Peter

 

XP2 is processed in C41 (colour negative processing), almost always done by a lab in a commercial machine. In that case there is no opportunity to adjust the process. In addition, Ilford in ther data sheet say that XP2 can be successfully exposed for a wide variety of ISO ratings (50 to 800) - and should always be processed the same way, regardless of the exposure rating. So no tinkering and no decisions.

 

For what it's worth, I use XP2 almost exclusively, and I expose as for 200 ISO. I came to this conclusion by doing a standard film speed test, the one found in all Zone system explanations. The idea is to expose so that the darkest part of the scene produces a perceptable density on the negative. That way you will retain the details in the dark part of the scene, and in almost all cases get a negative with maximum information for printing. It also - in XP2 - has the advantage of slightly reducing the effect of grain. And the negatives scan very well and print georgeously.

[innerimager]

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Thanks a lot Michael. That's exactly what I thought, I just wanted to have it confirmed. I'm very happy with the results I'm getting from XP2 at 200 iso, and plan on trying 800 in certain situations. best....Peter