On 9/26/2014 7:06 AM, Chuck Norcutt wrote:
Ever since I read Mike Hattem's tests of adapters you've described below I can't figure out what he was carrying on
about. Consider that the front and back mounts are not perfectly parallel. How is that different from tilting a lens
with a tilt/shift adapter? And if it was a truly bad machining job... maybe only by 0.001-0.002 inch. The image is
not "distorted", only the plane of focus has changed. Unless he's testing using a perfectly flat object located very
close to the lens and with almost no depth of field and also very precisely parallel with the image plane I don't see
how he could detect it... even at 100%. I don't see that such a small error in the parallelism of the two mounting
faces is any kind of real world problem.
What's wrong with my logic?
Nothing at all, it's the same as mine, which found his assertions unlikely at best. Except for the usual problem with
theory - empirical evidence. It's been a long time, but I recall seeing a difference in the images he provided.
I don't now recall if the issue was parallelism, length, ??, but the same logic applies. And yet he had careful test
images showing a difference between adapters. Absent another theory, one is forced to consider that very fine machining
differences may matter. The differences were minor, and only visible in A-B comparisons at 100%, but certainly there.
Parallel Puzzle Moose
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What if the Hokey Pokey *IS* what it's all about?
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