In that case, I agree that you should test.
I generally perform two tests. They're not high science, but I can
separate the wheat from the chaff.
I have a 13 x 19 high-res print I made that consists of a series of
lines about 3/4 inch apart. The center line is twice as thick as the
others. With the camera on a tripod and aimed at the center line, I
set it up to approximate a 45 degree angle. I set the lens to wide
open aperture and in the middle of its zoom range. I then autofocus on
the center line and examine the results. This provides a good
indication of autofocus accuracy. I think you can find instructions
for similar procedures on the web.
To test the flatness of the focal plane and edge sharpness, I shot a
rough brick wall off a tripod. I use a bubble level on the wall and
camera to set everything up square. I shoot the wall at wide open ap,
and at both ends of the zoom's range.
Paul
On Sep 30, 2009, at 7:54 AM, eckinator wrote:
No, they gave me a NIB to keep and service was to return my old lens
to them to be added to their loaner pool. So since they are both
roughly the same age (10 weeks apart, my old one was almost new) I
doubt they will care so much. They are actually very kind and helpful
there. I took some non-scientific test shots and the repaired lens
indeed seems sharper but I want to know for sure.
Cheers
Ecke
2009/9/30 paul stenquist <pnstenqu...@comcast.net>:
I'm sure they have a record of the serial numbers and expect you to
return
the loaner.
The repaired lens should be very good. The repair techs are
probably much
more capable than the assembly line quality control people.
On Sep 30, 2009, at 7:35 AM, eckinator wrote:
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