Originally posted by KxBlaze But if you want to go further then you can use a Nikon, Canon, Sony, Olympus, Adaptall, Leica, pretty much any and every single lens ever made on a Pentax with a proper adapter.
WRONG WRONG WRONG WRONG WRONG!!
Some Nikon lenses can be used without adapters; some can't. Adaptall lenses merely require an Adaptall-Pentax adapter. Canon and Sony/Minolta lenses *can* be used, but only with adapters that degrade image quality. AFAIK Olympus and Leica lenses require surgery, or can only be used for closeups. (Did I miss an Oly-PK adapter somehow?) If my Canon, Leica, and Minolta lenses could be easily be mounted on my K20D, I would have done so by now.
Yes, almost any lens can be stuck onto a Pentax dSLR somehow. No, they won't always work well, nor in ways you expect. Yes, big Medium Format lenses (like Hasselblad, Kiev, Mamiya, Pentax 645 and 6x7, etc) can be mounted -- and they weigh a ton. No, itsy-bitsy Oly and Leica and 110 and m43 lenses don't work well on our dSLRs. Even Pentax has its limits.