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Re: [OM] lens and film contrast

Subject: Re: [OM] lens and film contrast
From: "John A. Lind" <jlind@xxxxxxxxxxxx>
Date: Sun, 09 Jun 2002 10:36:00 -0500
At 04:55 6/9/02, Roger Wesson wrote:
I disagree!  If photography is an art and not a science, then the only
criterion for deciding what is a good lens and what isn't is whether you
like the results it gives you.

Roger

It's --== both ==--.

The Art is visualized in the mind of the photographer. The Science is in the equipment film and processing used to realize the vision. For the Art to be effectively and efficiently achieved, the photographer must understand the Science so that Cause->Effect is repeatable, reliable and controllable. These are the underlying First Principles used by Ansel Adams in creating the Zone System as presented in his trilogy (The Camera, The Negative, and The Print).

Whether or not a lens has a high MTF at the low, middle or high spatial frequencies is objective. Whether this is a Good Thing or Bad Thing is subjective based on the vision of the photographer _for_the_task_at_hand_.

In working to realize a visualization, the _system_ must be considered, from lens->body->film->processing->enlarger->print material. It is very rare if everything fits _all_ the criteria exactly. This requires conscious trade-off decisions with priorities for the imagery (e.g. shutter speed versus aperture for exposure, or how hard a film will be pushed to get a usable exposure versus the increase in grain and contrast that results).

Exemplia gratia:

(a) I have a night cityscape made using Kodak's Portra 160NC. It is printed on Kodak Professional Metallic Paper. The print material has less latitude than the negative. It is printed to maintain detail in specific highlights while relinquishing some of the deeper shadow details _in_the_print_ whereas both are present in the negative. I selected this print material specifically for its appearance and surface finish (super gloss) _knowing_ deeper shadow detail would be relinquished. It was a tradeoff based on my specific goals and their priorities.

(b) Recently did another concert shoot at a local "blues jam." Consideration was made of which camera bodies, which lenses and which films to use along with how hard to push the films for this specific task. I selected P3200 (TMZ) and Provia 1600 after reading the data sheets on both films, and shot both at EI 1600. Why EI 1600 for P3200? Because there was sufficient light to use it at that speed, and the MTF curves and its contrast behavior when processed P1 (EI 1600) versus what it produces when processed P2 (EI 3200). It backs off from the graininess and contrast increase resulting from pushing it to EI 3200. This was an educated guess as I had used neither film before, but still educated based on their data sheets. I wasn't as pleased with the Provia as with the TMZ, not because Provia 1600 is a Bad Film, but because of how it behaved versus what I desired. I knew this risk because of Provia 1600's film structure and response curves on its data sheet, but had no experience to correlate them to resulting imagery accurately, just a general sense on where it was likely to go. The Provia turned out visibly grainier and the yield rate for larger prints is less than desired, although more might be acceptable (to me) for smaller ones.

The Science alone simply _is_ what it _is_ and cannot be labeled a Good Thing or Bad Thing. Whether or not its Cause->Effect for a specific image is a Good Thing or Bad Thing is a subjective evaluation of the Art made in the mind of the photographer (let the critics be damned).

-- John


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