ATK writes:
<< I have a couple questions about Gary rating of lenses.
First -- he rates the 90mm very high. Does this mean all (or most) zukio
90mm
will have a similar rating? >>
There are two difference 90mm f/2 samples on my WWW page. But they were
tested using two different cameras, which probably accounts for most of
the differences. This isn't the sort of lens you would expect variations
in build quality for (like you would for a 50mm f/1.8 F.Zuiko, for
instance). It is also a lens that demands tight camera tolerances. As
we like to say, your mileage may vary . . .
<< Second, in general how do you compare the 85mm, 90mm and 100mm f2,
100mm f2.8. Hum -- what I mean is that in addition to raw rating do you
see much difference between these lenses in quality of picture ? >>
Volumes have been typed on this List regarding that very topic. The
keyword is "quality." You have to define quality to be able to get an
opinion (note there are no "answers"). Each has its own
characteristics.
<< (Also if the camera is hand held would the rating between these
lenses be much different)? >>
You bet you! Herbert Keppler has been testing and writing on that
subject for years. You might even do better if your only light is
electronic flash, but certainly poorer hand held (except maybe at
shutter speeds of 1/(50x the focal length) or greater, like 1/250th or
greater for a 50mm.
<< Third -- does different focal points impact your rating -- if the
image is 4, 12, 100 or 1000 feet from you are you going to get the same
crispness you would get according to your rating ? Would your rating for
the
various lenses be different ? >>
They will vary. Macros will fair better closer than the 1:40 ratio I
tested at. Non-macro primes would probably perform better at infinity.
But can you imagine how much information overload it would be to repeat
all this data for multiple magnification ratios?
<< Fourth -- what is the easiest way to rate a lens to see if the one
you purchase matches the one you read about (using Gary's chart how do
you decide if the image is a,b,...) ? >>
There isn't an easy way. In fact, with the obsolescense of the original
Fujichrome 64T, these exact test conditions are no longer repeatable.
Gary Reese
Las Vegas, NV
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