> "Ken Durling" <[EMAIL PROTECTED]>
> How do you check for decentered elements?
Hi Ken,
A gross test is to look for impact damage on the barrel, and
confirmed by shaking the lens and listen for glass rattling
inside or bits falling out :-)
Check for uneven sharpness, or asymmetrical internal reflections.
And for sharp focus shifting around the frame during focussing.
And for shifts occuring when the lens is rotated unlocked in the
EF bayonet mount.
http://www.photozone.de/canonFAQ.htm#IvsII
http://subclub.org/field/test.htm
http://www.photo.net/bboard/q%2Dand%2Da%2Dfetch%2Dmsg?msg%5Fid=001Pgy
http://edmundoptics.com/techsup/tsb/opticalspec.cfm
Cheers
Julian Loke
P.S. Bj�rn R�rslett tested a batch of new Nikkor 17-35 AF-S lenses,
and found "2 out of 10 lenses has severe decentering problems"
http://foto.no/nikon/17%5F35%5Freview.html
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