07-08-2013, 01:08 PM
Thank you for your opinions, Markus and Shapito.
I have checked the effect of field curvature. It does not look like there is strong field curvature. In the attached image I focus at the left and right borders (I did not try to make the target plane to be parallel to the image plane in the vertical direction but tried to make the left border and the right border have the same distance to the camera). It appears that the center region is well in focus (I did check this with manual focus). As you can see, the left and right border regions are much more contrasty than the central regions. I would say that the borders are not very soft, but the center is very soft.
I also checked the lens for defects like fungus but I did not find defects with my naked eyes (I did make the aperture fully open and used a back light source for the check).
Kind regards,
Frank
I have checked the effect of field curvature. It does not look like there is strong field curvature. In the attached image I focus at the left and right borders (I did not try to make the target plane to be parallel to the image plane in the vertical direction but tried to make the left border and the right border have the same distance to the camera). It appears that the center region is well in focus (I did check this with manual focus). As you can see, the left and right border regions are much more contrasty than the central regions. I would say that the borders are not very soft, but the center is very soft.
I also checked the lens for defects like fungus but I did not find defects with my naked eyes (I did make the aperture fully open and used a back light source for the check).
Kind regards,
Frank