First, may I assume that the title is a typo? Or do you have access to a
special source of lenses not available to the general public? All I can
find is a 28-70/2.8.
Chuck Norcutt wrote:
> .............................
> On the other hand the thickness of the adapter should only affect focus
> at the extreme ends of the range. As it was I was focusing about 3 feet
> away and had plenty of focus travel on either side of the distance to
> the target. Even if the adapter thickness is off it shouldn't matter
> for this test.
>
I agree about the adapter thickness.
> What does matter is Chuck's eyes. Anyhow, more testing and checking to
> go.
>
I believe much of your problem may be the 3 foot test distance. Ordinary
lenses are optimized for longer subject distances. Gary did all his
tests at 1:40
Some time ago, there was a thread about the 21/3.5 where close up shots
of a map showed that its reasonably flat field at longer distances
became VERY curved at closer distances. I believe overall sharpness went
down as well. What you are testing is close-up performance, not general
performance, which is not generally all that great with the pre f2 Zuiko
WAs.
Same thing with the Kirons. The 28-40/4 is not listed as a macro lens,
while the 28-105 was sold as a macro lens. Not surprisingly, the one
designed to perform better at close focal distances is the one that did
ok in your test. Get out the tripod and put the test subject out there
to 5 feet or more for 28mm and 10-15 ft. for the longer fls and I'll bet
the results change.
Moose
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