Paul
On Mar 19, 2005, at 5:46 AM, Alan Chan wrote:
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
__________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/
