--- Shel Belinkoff <[EMAIL PROTECTED]> wrote:
> ...
> There have been some comments on the list to the effect that
some
> manual focus Pentax lenses don't produce very good results
when
> used with the istD(s). A little more information is needed.
> Which lenses are giving poor results? In what way are the
> results poor? When using a particular lens, are the problems
> only in certain circumstances, or across the board. I've seen
> some awful looking results with some longer lenses (Paul's
bird
> shots), but they seemed to be relegated to backlit scenes. So,
> any comments on the quality of images with various manual
lenses
> would be appreciated. Reasonably sized pics (sections of
larger
> images) might be helpful as well.
Digital sensors are very unforgiving about off-axis chromatic
aberration, much more so than film, and focal length can make a
greater difference as the interaction of the sensor's lenses and
the angle of incidence from light coming from the lens can
exacerbate whatever issues might be there. There are processing
techniques that can be used to reduce these problems as well.
Blooming at high contrast junctures is another issue where
sensors differ from film response. Thin tree limbs against a
white sky, etc, show this up very clearly. Often the blooming
turns colors (purple, red, magenta, green) depending upon the
specific camera and sensor. Lenses don't contribute to this
directly, but how well the lens manages flare has an effect on
the image quality which can add to or diminish how the blooming
looks.
The good news is that I have not seen much in way of issues with
the Pentax mf lenses I've acquired. I've acquired a lot of them
in the bare six weeks since I bought this camera, focal lengths
from 24mm to 200mm mostly A series, and all of them seem to
perform very nicely. The A24/2.8 seems to have a bit more flare
than the A28/2.8, the M85/2 as well; The Takumar K 135/2.5 is
only single coated but with a deep lens hood does very
respectably. I can't say that my results are looking
substantially different from what I used to get with similar
lenses on film. I haven't seen Paul's bird shots so I'm not sure
what exactly you're responding to there.
I have heard from one or two friends that the FA24/2 AL has
quite a bit of CA at wide apertures on the D/DS, but is well
controlled when stopped down. I've also heard one or two
suggestive side references that the FA28/2.8 has a similar issue
but then I've also heard that the FA28 is brilliant and
excellent. ?? Some have mentioned that the FA100 macro has CA
issues which the D-FA100 macro eliminates ... Again, I have no
direct experience, but have heard testimonials in both
directions.
Overall, however, I wouldn't put this issue up as a barrier. So
far, the Pentax lenses I've used on the DS have proven to be
excellent, whether old or new, and all seem to have such
beautiful imaging character that I'm very happy to have moved
into this camera system with the DS from my Canon gear.
Godfrey
__________________________________
Do you Yahoo!?
Yahoo! Mail - 250MB free storage. Do more. Manage less.
http://info.mail.yahoo.com/mail_250
