From: ka1gt@cbnewsm.cb.att.com (robert.m.atkins)
Subject: Re: Popular Photography & Chasseur d' Images  (sp?)
Organization: AT&T
Distribution: na
Date: Fri, 18 Dec 1992 21:27:29 GMT

In article <1992Dec17.213804.8515@cunews.carleton.ca>, ioannis@isis.sce.carleton.ca (Ioannis Lambadaris) writes:
> I was in Magazine/News store in Montreal last week reading the
> well celebrated French magazine Chasseur d' Images. There was a test
> for the Tamron 35-105 f2.8 zoom lens (I am pretty sure that was the lens)
> and to make the story short, this optical wonder received 2 stars a modest
> rating. Popular photography found this lens to be well above average!!!!

It's worth noting that most lenses are above average. Average in popphotog
speak doesn't mean average in the sense of "the mean of a data set". It
appears to mean average in the sense of "just OK" when it comes to lenses.
In the old Modern Photography tests I never saw ANY lens rated below
average. If they described a lens a average, it was a real dog! They also
rated any 500mm lens that could resolve 25 lp/mm in the center of the
frame as EXCELLENT, wheras I would regard such a lens as a paperweight at
best and not worthy of attaching to a camera. At 18 lp/mm is was rated
good! Standards appear to differ.

> 
> In another occasion Popular tested two Canon autofocus 50mm f1.8 lenses
> and the old version was found very good (the one with the focusing distances
> included) while the new version (with no focusing distances) was so so.
> Of course the newer lens was rated highly although there was a big
> difference between the charts of the two lenses.
> 

These two lenses are supposed to have identical optical designs.

> In another occasion Popular presented a test of a Nikon lens (cant
> remember exactly since I misplaced the pages during a move, I intent to
> search and give details, but I think it was the 28-70 zoom) where the
> color corresponding to performance B+ (normally orange)
> was light red giving a false
> impression that the performance was A (but not A+ deep red) should somebody
> was scanning the test without reading the numbers. The principle
> is the reder the lens the better....
> 
> I understand that there are no absolute criteria in this world but what 
> someone could conclude based on the above mess?
> 

I conclude that that Popular Photography sometimes does a sloppy job when it
comes to checking the accuracy of their articles. There are numerous examples
that come to mind. Their lens tests should be taken for what they are. A
single test of a single lens. Most of the time this will give a good idea of
lens performance - but sample to sample variations cannot be ignored, and the
lens you buy may be better or worse than the one they tested. Their tests will
pick out real dogs and real winners, but in the middle ground things are less
certain. To my mind they have never properly explained the process they go
through to come up with their SQF ratings. They did give a superficial and
confusing explanation when they started their new lens tests, but it didn't
explain much to me. How do they rate sharpness, contrast, astigmatism, field
flatness, center vs. corner performance etc. etc. into the SQF number??
Do you get the same SQF for a lens which is a fair performer across the whole
frame and one which is superb at the center and lousy at the edge?? If they
didn't treat us like idiots they could publish their real test data and let
us judge which lens performed best.

===============================================================
Bob Atkins  AT&T Bell Labs  email (direct)  att!clockwise!rma
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