Olympus-OM
[Top] [All Lists]

[OM] lens and film contrast

Subject: [OM] lens and film contrast
From: "William Sommerwerck" <williams@xxxxxxxxxx>
Date: Sat, 8 Jun 2002 19:19:31 -0700
"Too much contrast at multiple stages of the image chain can be a problem.
Use a contrasty lens with contrasty film with sun and sand or
snow and it's problematic to capture any highlight and shadow detail."

This remark shows a misunderstanding of what lens and film "contrast" are.
They're not the same thing.

When we say that a given photographic material is "contrasty," what we
really mean is that it has a short tonal scale. The original three-strip
Technicolor is an excellent example of such a "high-contrast" material.
Scenes shot under bright sunlight are downright garish, with little shadow
detail and the highlights on the verge of burning out.

Lens contrast is an altogether different matter. A lens can only degrade
image contrast, either by having a poor MTF at low spatial frequencies, or
by scattering highlight light into the shadow areas. A lens that does either
of these things is _not_ a good lens, even if it provides the kind of images
we prefer.

If you want low-contrast images, it makes more sense to:

>> choose color materials with a longer tonal scale
>> overexpose and underdevelop black-and-white materials
>> use a weak fog (or similar) filter on the lens

Unless I were buying a special-purpose lens (such as a soft-focus portrait
lens), I can't imagine why I would want a lens that wasn't as sharp and
contrasty as possible. You can always degrade what's good, but you cannot
put back what isn't there.


< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz