On 2/13/2022 1:47 PM, Mike Gordon via olympus wrote:
. . .
https://www.olyendomike.com/Oly-7-1428/
I did not take the images at all to compare across platforms, but the
difference is obvious.
The sigie had a tad of sharpening to each and no distortion correction.
https://www.olyendomike.com/Sigma-14-24-f28-centering-200/
I'm not sure I "get" this technique. Not only visually disorienting, but highly
subjective and non-repeatable/comparable.
I use a terribly simple test target.
<http://www.moosemystic.net/Gallery/tech/Lenses/PanvsOly25mm/_B170563web.jpg>
Yeah, I know. Not all the targets are level, some warping has occurred to the paper over the years. But it does the job
of useful comparisons. I added smaller bar sets to the AF target, and have yet to try a lens that gets the smallest ones
sharp.
Two shots, and you can compare a pair of lenses wide open, absolute resolution and centering. Pull the corners over the
center in PS, crop, and you've got a good comparator.
You tell me; can't you clearly see the differences, wide open, between these highly rated and very similar lenses,
including centering? <http://www.moosemystic.net/Gallery/tech/Lenses/PanvsOly25mm/PanvsOly25mm.htm>
The target is designed for 4/3 sensors. The paper targets are in 4:3. Fill the frame with them, and you can compare
tests taken at different times. (The above were all at the same time.) Repro ratio is then 1:44, a little farther away
than the standard 1:40. Square is easy, set lens height equal to center of target, distance from wall same for lens and
target.
In practice, I've found it works for FF comparison to 4/3. Height to fill frame. If fastidious, one might make another
target for FF, 38 x 57". I used a corkboard so I can hang it in different places, as physical distances vary a LOT, long
tele vs UWA. One could just stick the targets on a basement wall, or such.
Gamma Test Moose
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What if the Hokey Pokey *IS* what it's all about?
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