On 3/21/2017 4:17 PM, Mike Gordon via olympus wrote:
Master Lever manipulator Moose writes:
<<OTOH, the Bee Fly shots are shot from a little closer than the lens will focus on
its own, an estimated 1.1 m, vs. the spec minimum of 1.3 m. Moving back to 1.3 m would make
the magnification disparity greater, but might I have gotten slightly sharper images? I
dunno. <<Practically, when ephemeral subjects show up, it's grab and shoot what's on
the camera.
<<In practice, the T226 may not be the best choice. Adding it's 2260 mm FL to the
distance from it's front to the sensor, it's maximum focal distance from sensor is ~2.54 m,
so there's a huge overlap with the 1.3 m native close focus. If, like the 14-140, the lens
was soft at the <<long end and closest focus, the choice would be different. When
focus at 40 m, through a C-U lens, is softer than @ 2.45 m without, though . . .
<<The T132 1.6 m max. overlaps much less with the native lens, and it magnifies
more. The 0.95 m of the 5T leaves a coverage gap, but that's usually not an issue.
Most interesting, and not necessarily what I expected. Older mid tele zooms often
had better IQ at infinity with a high quality CU diopter than at MFD--not the case
with the PL100-400. Performance is clearly aperture dependent as well but less so
for central sharpness. There are so many variables almost need to generate a 3D
response surface after a zillion imatest analyses, but then would not have time to
do anything but tests. I had thought the T226 at 400mm at closest focusing distance
might yield good results for smaller flutterby's still with adequate working
distance. The 'effective" mag should be a bit shy of 1:1 which is about right
for Hairstreaks. I wonder how a similar mag with the T132 would compare--hard to
predict. The native lens is a bit sharper at shorter FL's as well. A couple shots
of a fresh dollar bill may sort it out. The downside with longer working distance
is it magnifies the effect of camera shake.
Yeah, one more complication I didn't figure in. It's possible the difference I see is IS differences. If it thinks it's
working at 40 m, and it's actually 2.45 m, the IS could be the difference. Darn, the softness could easily have the
character of motion blur. When I tested the 5T against the 500D, it was all solid tripod, IS off, etc.
Crumbugs! I dislike careful testing using boring subjects. Even though it is
often important to know what it reveals.
It's All too Various for Moose
--
What if the Hokey Pokey *IS* what it's all about?
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