Having tested one Sigma with the Tokina
doubler I decided to test the 400/5.6 APO as
well. I set up a tripod outside and took some
pictures of twigs on trees and stalks
protruding from the snow. I was looking for
the usual aberrations and found them. Towards
the edges of the image, when blown up to 200%
in Photoshop, the fuzziness on one side is
blueish and on the other pinkish. This
reverses on the opposite side of the frame as
expected. These fringes are also visible on
out of focus stalks and twigs at the edges.
The in-focus parts of the image show no
chromatic aberration until blown up very big
when the fuzziness is blueish on one side and
pinkish on the other. But the image is so
pixelized (pixellated? posterized?) at those
magnifications that no one would look at them
like that anyway. At normal viewing
magnifications there are no disturbing
chromatic artifacts except in very contrasty,
completely out of focus objects, at the edges
of the frame.
I'm satisfied. For a cheap, not highly rated
telephoto, its not bad. Its no Questar but
what can one expect for a few hundred
dollars? They doubler seems to work with this
lens. Contrast is not great but that can be
fixed. I haven't sharpened the two images but
did adjust the levels a bit to get the two
images more or less the same.
http://www.kolumbus.fi/mimosa/HOLD/1888s.tif
http://www.kolumbus.fi/mimosa/HOLD/1890s.tif
The stalks were about 40 metres away and the
small tree branches about 50.
I also tried using the shutter without mirror
lockup and there seems to be no discernible
difference in sharpness between those and
exposures made with the normal arrangement
(with the mirror clanking up just before the
shutter opens.) Aperture was 5.6 and shutter
speed was about 90s. In camera sharpening is
off. No birds were obliging enough to pose.
This setup needs a rifle sight it's hard to
find things. And no feathered friend would
wait long enough for me to find him, her, or
it. Its warm now (-5.5C) and I was able to
work without gloves.
Don
--
Dr E D F Williams
__________________________________
http://www.kolumbus.fi/mimosa/index.htm
http://personal.inet.fi/cool/don.williams
See feature: The Cement Company from Hell
Updated: Added Print Gallery - 16 11 2005
