contrast modification through over/under exposure ?

[bonk]

I have a little noobish question: How does the contrast of over/underexposed negative film and positive film change? Can I influence contrast by modifying the exposure of the film ? I have searched through Fred Pickers's "Zone VI" and Ansel Adams' "The Negative" but couldn't find as hint on this one.

 

[Donald Miller]

Underexposing and overdeveloping will increase contrast. Overexposing and underdeveloping will decrease contrast for negative films. This is within reasonable limits, of course...extreme underexposure will lead to no image. Extreme overexposure will lead to excessive density and the density piling up and blocking on the shoulder of the film's curve.

 

[smieglitz]

The contrast of the film is mainly influenced by changes in development. More development gives increased contrast and less development gives decreased contrast. Both overexposure and underexposure lower contrast.

Having said that, you can change contrast through exposure errors that have important parts of the scene fall on the toe or shoulder of the curve. These areas have inherently lower contrast than the middle straight-line portion of the curve. Wherever the curve is arched, the contrast is lower than the adjacent straight portion.

Underexposure and overexposure push areas of constant (hopefully "normal") contrast into these lower contrast regions and affect the detail that should be present in them.

Joe

 

[Chuck_P]

I have a little noobish question: How does the contrast of over/underexposed negative film and positive film change? Can I influence contrast by modifying the exposure of the film ? I have searched through Fred Pickers's "Zone VI" and Ansel Adams' "The Negative" but couldn't find as hint on this one.

You'll need to take a closer look at those two books. We have all been new at one point so keep plugging away. Modifications in exposure (i.e., something different than a proper reflected or incident reading) generally imply some modification in subsequent development.

The concepts mentioned by Mr. Miller should well understood as they will be the foundation of your understanding about exposure and development. If you are getting into the zone system, Picker and Adams' book are two good sources (though some find Adam's book difficult to understand, I suggest it will be as difficult as you make it).

good luck
Chuck