Guys I have discovered a weird problem which I cannot come up with any 
explanation
so I need some guidance. Some recent shots have revealed that about 1/5 on the
right-hand side of the picture is blurrier than on the left-hand side under 
normal
shooting condition (aperture f11 for all samples).

http://www3.telus.net/wlachan/cb.jpg (1.7MB)

To double check, 2 identical shots were done, 1 with the camera grip (blurry 
side)
pointing up (ru.jpg), and the other pointing down (rd.jpg). This test confirms 
the
previous finding. The bottom edge of rd.jpg is blurrier than the bottom edge of
ru.jpg.

http://www3.telus.net/wlachan/ru.jpg (2MB)
http://www3.telus.net/wlachan/rd.jpg (2MB)

Now is the weird part. I did some careful test on a 2D subject (aligned with 
bubble
level and shooting straight down at very close distance, about 0.6m) but there 
is no
trace of blurry edge/corner at all. Both sides of the picture look equally 
sharp, or
at least I cannot tell the difference.

http://www3.telus.net/wlachan/f11.jpg (2.8MB)

So what is going on? I have never noticed such interesting issue with my next 
widest
lens FA*24/2 which is pretty sharp down to the corners for scenery. I thought a 
lens
like this would perform worse at close distance, but it's not acutally??

Alan Chan
http://www.pbase.com/wlachan


                
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