Sir, I feel you must deliberately miss my point. I can tell you one thing
that's not MY problem, but it wouldn't be nice.
Tom C.
From: "Herb Chong" <[EMAIL PROTECTED]>
Reply-To: pentax-discuss@pdml.net
To: <pentax-discuss@pdml.net>
Subject: Re: Manual Focus Pentax Glass on istD
Date: Wed, 23 Feb 2005 18:10:00 -0500
if you can't have someone pick up one of your lenses and answer the
question "is this any good?" in a few words, what have you been looking
at? this isn't about high precision classes with confidence intervals and
null hypotheses. you don't need an MTF curve to say that this lens is one
of your best. this is about you sitting down and saying this is good, this
is better, and this is worse.
we can have a few dozen people do the ranking and run Spearman's Rank
Correlation Coefficient on all of the combinations and then correlate them
with MTF curves, coma, chromatic aberration and a host of other
measurements, but that's not the point. the point is that each one of us
has an internal notion of which of our lenses are better and which ones are
worse, and the line slides to move more lenses to the worse side when your
judgment is initially formed on the their film performance.
what this boils down to is that if you have a choice of lenses to do a
particular job, you will carry the best one for the situation. if you know
what one that is, you have already made the value judgment that i'm telling
you about. if your judgment is completely random, that's not my problem.
Herb....
----- Original Message ----- From: "Tom C" <[EMAIL PROTECTED]>
To: <pentax-discuss@pdml.net>
Sent: Tuesday, February 22, 2005 11:33 PM
Subject: RE: Manual Focus Pentax Glass on istD
Re: scientific... My original words were meant to mean that 'taking a 1000
frames with a number of lenses' on a film body and then comparing them to
' a 1000 frames taken with the same lenses on a digital body' is not a
conclusive test. Hardly anything could be determined unless they were
taken of the very same subjects, from the very same vantage point, under
very controlled conditions. And then studied very carefully. And then
that doesn't mean that a given lens still doesn't perform admirably in
it's sweet spot. Obviously a lens that performs admirably over a large
range of apertures and lighting conditions may be more desirable than one
of more 'limited' usability.
