Atk writes:
Also -- (unrelated) if you shoot with focal lenths 24mm to 90mm at
250/s
to 1000/s how much degrading in image will you see if you don't use a
tripod
There were periodic tests of this done in the USA photography magazines
through the 1970s and 1980s. Camera shake with a 50mm lens hand held was
almost completely dampened by 1/250 and gone by 1/500, if I remember
correctly. In one test they used about 5 different editors and compared
their unique handholding technique. They were differences between the
people. I concluded that a shutter speed equal to the reciprocal of 5x
the focal length was a good aim point. For example with a 50mm lens,
1/5(50) = 1/250th sec.
<< I know this is a vague question -- so what I mean is hand held camera
shake
on average (more vagueness) worse than the vibration from the
shutter/mirror? >>
A vague answer is that camera induced vibrations are about like shooting
a 50mm lens hand held at 1/125th sec. Comparison of the
photomicrographs of resolution test targets as published in Modern
Photography would answer that (in various Herbert Keppler columns and
articles). BUT, cameras vary widely as to their vibration levels.
I suppose I can try a test sequence hand held and find out.
<< Unrelated (and even worse question) in gary test is the difference
between
an 'A' grade and 'B' grade visible in an 8x10 without the aid of a loop
(I guess this question is specific to Gary since it is his subjective
rating)... >>
The A lens will seem more contrasty than a B in an 8x enlargement, but
you won't be able to detect with your naked eye the higher resolution of
the A over the B. You will be able to detect lower resolution and
contrast in a C grade vs. an A grade at 8x enlagement. I'd say the
enlargement limits to my various grades would be about:
A = 24x36"
B = 11x16.5"
C = 5x7.5"
Those are the limits before detectable image deterioration starts to
appear. Those limits could be increased with a film that has a higher
resolving power than Fujichrome 64T. They also represent rough guesses
through eyes that aren't as good as they used to be.
Just look at the charts in any Popular Photography SQF lens test. As
they evaluate smaller enlargements, the grades get proportionately
better. Most of the lenses tested get A's in the smallest enlargement
sizes.
Gary Reese
Las Vegas, NV
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