Barry B. writes:
<< What happened at f/2.8 [causing a VG rather than an Ex rating in a
Modern Photography lens test]? Looks like testing error. >>
Nope, no error. Modern Photography had a sliding scale for ratings at
various apertures. The criteria for Excellent at 3 stops down was more
stringent than wide open or one stop down.
With that said, it should be noted that Modern changed their critera for
Exc, VG, etc. over what it was in the 1970's. Don't make the mistake of
comparing early lens test ranks with late test ranks! Go with the
resolution (and contrast) data only.
Also, the film used (Panatomic-X ?) for testing improved over that
period. That was another variable that confounded the data - but they
never publically admitted it. I think the results also suffered from
variations in vibration from the camera bodies used - just like we've
discovered with OM-1 vs OM-4T/OM-2000 comparisons.
Gary Reese
Las Vegas, NV
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|