[Adam]

Thanks for the previous message. Will the newer Pentax HD PENTAX-D FA 28-105mm fit on a ist D body? I am confused about A vs K mounts?

The compatibility of those two is summarized here:
Pentax *ist D and HD Pentax-D FA 28-105mm F3.5-5.6 ED DC WR - Compatibility | PentaxForums.com

You can learn more about the different Pentax lens mount designations below:
The Evolution of the Pentax K-mount - Articles and Tips | PentaxForums.com
Pentax K-Mount Lenses Explained: The differences between various Pentax lens series


The A mount is something Sony uses, but the KA mount is the second-generation version of the Pentax K mount which supports aperture automation. Most modern lenses are either KAF2, KAF3, or KAF4.

As a rule of thumb, Pentax lenses older than the camera are fully supported, but lenses newer than the camera might have some limitations (though they will always fit and almost always work with basic functionality).

Adam
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[coondog]

HI Adam You must realy love these guys to stay hear as long as you have. I have tried to find M37 to M42 lens mount rings for ASAHI EXTENSION TUBES & M37 Asahi lens. but can only find one for $ 12 can you tell me where I would ask everyone if they want a few. I might have a batch made up for us. thanks for your time.

[photolady95]

Adam stays here because he created PentaxForums, and co-owns it with his dad.

As an answer to where you can ask everyone, the wanted section is what you want. Post a question in there and you'll usually get an answer from others on the forum who might have what you're looking for or can direct you to where you might find what your looking for.

[coondog]

Thanks