I suspect my 28-135 IS to be an almost good copy.
How can I test it?
I searched previous postings and have found so many tests, but these seem to be specific of some lenses, or partially inclined to test a specific aperture. Is there a "design" test for this lens?
Tried the Canon site with negative results.
|Umbrellas by pleytime|
from An A to Z of Subjects- Week 21, U
|Glass ball on a perforated metal plate _2 by harubux|