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What are you showing us in the linked image?
The image does not contain exif-data or description, it is by far to small
to say much about it, you don't tell about the circumstances under which
you took those images ... this seems to a clear case for my cristal ball ...
but is that the type of answer you are looking for?
the picture is a dump from LR at 200% . Aperture is 1.8 and 2.8 shutterspeed is 1/2000 for the 1,8 shot. i think it is possible to judge the pictures, espesially if you have seen a sharp/unsharp 31mm ltd before
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Well, the obvious first:
The f-2.8-image is better than the f-1.8-image ... this is something very common ...
use a lens wide open, and use it stopped down a bit, and image quality increase.
What I don't like, is (besides reduced contrast which would be ok) the way it behaves
on the contrasty white edge ... this seems to me as if a cheap UV filter has been on the
lens when taking this image. I mean ... it is clear that this shot is for test purposes ... since
there is nothing in this image requiring f/1.8 ... nevertheless, one wouldn't expect this in the
image center.
thank you very much for the tip, I will perform this test as soon as I get back from holiday. When using a Pentax K5 with tripod and AF focusing; the result will be unsymetrical and somewaht blurres images on edges(not the eges of the frame) of the target object. Probably a good idea to test the 18-135 zoom at 31mm focal length too?
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[quote name='chals' timestamp='1311582322' post='10223']
thank you very much for the tip, I will perform this test as soon as I get back from holiday. When using a Pentax K5 with tripod and AF focusing; the result will be unsymetrical and somewaht blurres images on edges(not the eges of the frame) of the target object. Probably a good idea to test the 18-135 zoom at 31mm focal length too?
[/quote]
In the dead center the edges should be perfectly symmetrical regardless of the lens.
You can, of course, check the 18-135 but this is independent from the 31 in any case (unless we are talking about a camera defect).
Remember to switch off SR for the procedure.
