I ran across this in the MTF article on Erwin Puts' site:
"Then I check for decentring on the optical bench. As a side line I
may note the much acclaimed tests from Color Foto magazine (those
famous two million data!) are critically wrong on the decentring
issue. In one of their latest issues, they noted a decentring of
about 8% for several high-grade lenses. This cannot be true! I
happened to be present when the lab that does the tests for CF, did
some tests: they put a camera in front of the testchart on a tripod
and manually/visibly align the camera for the test chart: a
notoriously difficult procedure and when using test data that are
measured by computer, the results do not tell you anything about
optical decentring, but only about the skill of the operator to align
the camera."
http://www.imx.nl/
I was interested because it confirms my suspicion when some tester is
questioned about a result that is at variance with other other tests
and says it is sample variation, or someone passes off their bad
technique as getting a bad edition of the lens.
Winsor
Long Beach, California, USA
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