But what are you trying to compare, Bob? Evenness of illumination,
resolution, contrast ... what? A gray card will only show you
evenness of illumination. At f/2.8, it's a toss up between the two
50mm lenses to predict which will do better, although at copystand
distances I'd put my bets on the dedicated macro lens.
A D-FA50 macro lens is designed to be best at flat-field imaging,
stopped down to f/8-f/32, in the near-focusing range. An A50/1.4 is
designed for general pictorial use at wide apertures, and will not
perform at its best at copystand distances.
Comparing a DA40 and a M40 pancake makes more sense as they are both
designed to do the same job of general pictorial work.
Unfortunately, the only lens I've got of the above four is an
A50/1.4. I can shoot a gray card for you, but I doubt that it's going
to tell you very much.
Godfrey
On Sep 5, 2005, at 1:52 PM, Bob Blakely wrote:
What I would be interested in, then, is D-FA50 Macro wide open and
the A50/1.4 at the lowest common stop, or the DA40 and the SMC 40
at the lowest common stop.
Regards,
Bob...
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By all means, marry. If you get a good wife, you'll become happy;
if you get a bad one, you'll become a philosopher.
- Socrates
From: "Godfrey DiGiorgi" <[EMAIL PROTECTED]>
There are no "digital" prime lenses between 20 and 35mm. Pentax
lenses designed for digital SLRs, to date, include:
DA14
DA16-45
DA18-55
DA40
DA50-200
D-FA50 Macro
D-FA100 Macro
If I get a chance to set up my copystand and lighting, I'll make
a gray card exposure with the A24/2.8 or FA35/2, but I doubt very
much that you'll see anything different compared to making the
same exposure on a 35mm film negative and then cropping the
negative to the 16x24 sensor format dimensions.
Godfrey
On Sep 5, 2005, at 12:56 PM, Bob Blakely wrote:
Yes. Also, if one of you digital dudes would shoot a gray card
frame edge to frame edge with one of your digital primes (say
between 20 and 35 mm or so) and one of your film primes of
*equal* focal length, I would be interested in comparing light
fall off at the corners. Tripod mount camera on centerline wit
perpendicular from the center of the gray card. Light gray card
evenly with two side lights placed on each side of the camera
and such that there is no equal angle reflection from the light
to the card to the lens. No flash. Just like you were
photocopying art.
