Pushing color 100 ISO to 400?

[kivis]

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Has anyone ever done this? I heard that doing this produces results with tighter grain than shooting native 400 ISO color film.

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[ndjambrose]

You can't push colour film in the same way as b+w.

 

Silver based film has a chemical process that extends in a linerar relationship to extended processing time. Hence longer development times can be used to compensate for under exposure.

 

Color negative is different. Extended development pretty much does nothing, as all the development happens very quickly and then exhausts itself. This is one reason why all C-41 films of any speed can be processed together. Whether ISO 800 or ISO 50, the development time is exactly the same. They can be processed together in the same tank, and for very short times - 3 mins 15 secs in new developer.

 

Longer development times can only be used to compensate for depletion of chemicals, but not for differences in exposure. Once the dyes in the film layers are exposed by processing they can't get any more exposed. Hence the process stops. Too much development beyond the natural stop point will degrade the dyes rather than improve the exposure.

 

But - and this is why people sometimes think colour negative can be pushed - the actual latitude of colur film is quite wide. Your could probably under expose by 2 stops and still have reasonable results, except perhaps in very low light. So you can shoot 100 speed at 400 but just process it normally. Latitude will take care of it.

[Mike Rawcs]

My understanding is that you can overexpose colour negative film, but not underexpose. If you overexpose you will get a denser negative, with good colour. If you underexpose you will get a thinner negative, with dull, mushy colour. I don't know how scanned film copes with over or under exposure.

 

Mike.

[nibbler]

There are no techinical barriers to pushing colour negative film. However, since there is no (practical) way of compensating for the underexposure, it becomes impractical in the real world. If you really want to push colour then use E6 film and develop it at home. Even better, just produce the desired effect digitally.

 

But using the wrong film for the given conditions does not produce `tighter` grain. What you want to do is to produce technically sharp shots with sufficient contrast. These can then be manipulated to produce grain, if that is what you want.