Lens compatibility back to all Pentax M-42 and K and KA mount lenses.
You can still put all those Adaptall lenses to good use. Here's a
response I got from a Pentax user when I asked about compatibility with
the older lens lines:
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You can use any M42 screw mount, K or KA lens on any of the Pentax *ist
DSLRs.
With M42, you obviously need an M42 - K bayonet adapter. You focus at
full aperture then stop the lens down to the taking aperture before
taking the meter reading.
With K, you don't need an adapter, and you can focus at full aperture.
The following applies to M42 or K: Depending on which *ist DSLR you are
using, the procedure is slightly different, but a press of a button
stops the K lens down (the m42 lens is already stopped down) to the
selected aperture, takes a meter reading and sets the appropriate
shutter speed. It's like a single shot aperture priority AE.
If you carry on taking pictures without obtaining another meter reading,
the camera will continue with the same shutter speed. If you need a new
meter reading, just press the button again and the camera will select a
new shutter speed.
It sounds complicated, but it isn't. You can master it in 5 minutes.
It works great. The exposures are spot on, every time.
With KA lenses it is even better. You get all the exposure modes the
camera body offers. So KA lenses give you program AE, shutter priority
AE, aperture priority AE and metered manual. Obviously there is no
autofocus, but you do get focus confirmation.
The backward compatibility offered by Pentax is the best of any brand of
DSLR. You get to use legendary Pentax and independent lenses in M42, K
and KA bayonet mounts. The one shot AE mode is great - you can take
several shots of the same subject knowing all will be consistently
exposed. This is particularly useful when shooting several shots that
you will later stitch together, such as a panorama.
The only other DSLRs that offer compatibility with manual focus lenses
such as our beloved Kirons is Nikon, and only on their top D1* and
D2* models. Even those won't accept pre-AI lenses, whereas just about
every M42 and K bayonet lens will work on the Pentax *ist DSLRs.
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It's surprising that this exceptional backward compatibilty record isn't
given more press. I'm sure Oly could have done the same with the 4/3's
mount but chose not to. Maybe they figured it would hamper acceptance
of 4/3's by other manufacturers if the mount had faithful vs. similar OM
characteristics. Anyhow, lens compatibility is the real Pentax story.
Chuck Norcutt
Andrew Fildes wrote:
For the life of me, the only selling point I can see to
> the Pentaces is the 'smaller/lighter' claim. Anyone know better what
> their selling point might be?
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