Pentax K mount adapter
The Pentax K mount (also called PK mount) was introduced by Pentax in 1975. It is a bayonet type lens mount that was used by Pentax as well as a large amount of other lens manufacturers.
Pentax-K mount adapter for Micro 4/3, Nikon F, Canon EOS, Sony NEX E-Mount, Sony Alpha and Fuji-X cameras
There is a wide range of different adapters available for Pentax-K mount lenses:
Pentax K to Canon EOS adapter
Mounting a Pentax K lens to Canon EOS is unproblematic. It will allow you to focus to infinity. Of course, focusing and aperture settings are done manually. I would recommend that you get an adapter such as below:
Pentax K to micro 4/3 adapter (Panasonic G, Olympus Pen…)
Connectivity to micro-four-thirds is unproblematic. The adapter is always quiet large which will increase the “size” of your lens. Focusing to infinity works fine. The only major drawback is that the images are cropped compared a full frame SLR. Even a 50 or 80mm prime lens will feel like a telephoto. You can find the adapters here:
Pentax K to Sony E-Mount (NEX)
There are no issues using a Pentax-K lens on a NEX camera. Focusing to infinity works well. You can find the adapters here:
Pentax K to Nikon F adapter
As with most other adapters available for Nikon F cameras, infinity focusing is only possible with an additional lens element in the adapter. Thus, you might loose some image quality.
Pentax K mount to Fuji X adapter
Connecting a Pentax K lens to a Fuji-X mount camera is unproblematic. Focusing to infinity is possible. You can find the appropriate adapters here: