I've taken the plunge and ordered several Pentax SMC filters,
and would like to compare them to B+W and Hoya filters (because
those are the ones I have). However, I don't really know much
about testing procedures, so I'm asking the list for some
suggestions.
Here's what I'd like to do:
First, shoot a few frames of slide film with one of Pentax's
finest lenses, sans filter, and using a few different apertures
- wide open, a stop or two down, f/8.0 and f/11.0, and at the
smallest aperture. Then I'd repeat the test, using the same
apertures, with each filter.
My first thought is of which lens to use. It's been said that
longer lenses suffer most from image degradation when used with
a filter, so it would seem that a lens in the 100mm or greater
focal length would be a better choice to see any degradation
than, for example, a 50mm or wide angle lens. So, here are the
lens choices. Which do the "testing mavens" suggest as being
the better lens for this experiment:
A*85/1.4
K85/1.8
K105/2.8
K135/2.5
M150/3.5
A*200/2.8
A*300/4.0
A100/2.8 macro
A*200/4.0 macro
I'm thinking that the faster lenses may be the better choice as
the difference between wide open and a mid aperture is greater,
and any qualitative differences between wide open and smaller
apertures may be easier to see.
A test for flare and image degradation by a light source just
inside and just outside the frame seems like a good option.
Since the sun could vary somewhat in its intensity if I
couldn't shoot everything at about the same time, would an
incandescent light source work as well, or should I try to get
everything done at once using the sun as a light source?
What might you recommend as a test subject? Using something
that doesn't move seems ideal, although a brick wall may not
provide the sort of visible detail needed.
Any other testing suggestions?
Bill, would you be willing to examine the results under your
microscope? I know you've got a pretty full plate with the PUG,
so let us know. Does anyone else have the ability to examine
and photograph slides for this experiment?
Is slide film the best choice for this? It seems to allow for
fewer variables. Can someone make a case for color negative
film?
--
Shel Belinkoff
mailto:[EMAIL PROTECTED]
"The difference between a good photograph
and a great photograph is subtleties."
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