confuse by all type of mount.

This might sound dumb but all this time while hunting for new lens online,I kept wondering how should I know that lens can fit to my Kx. I understand that every brand have their own mount. Example:

1)Pentax Screw Mount: 2x Teleconver with Case
2)Super Takumar 55mm f1.8 m42 pentax
3)SIGMA 70-300MM 1:4-5.6 APO MACRO SUPER LENS PENTAX DSLR

Im afraid if I got the wrong lens. It much more easier if they mentionit compatible with Kx but sometimes they dont.

Please help.....and thanks in advance.

I just bypassed a Pentax-made lens because the guy had been using it on his Canon camera.

DID Pentax manufacture lenses with other types of mounts? Or could this guy have a Pentax-to-Canon adapter on the lens and not know it?

Don: Thanks man. You have been my guru from the first day I join the forum. Will surely avoiding Ricoh K-mount

JohnX: There are some cheap and great M24/screw lenses out there,but budget tight.No room for adapter.Better invest in 1 great lens rather than buy 2 very good lens.

Some Canon users do know Pentax lenses are top performers, so they perform "surgery" to transplant a Canon bayonet to a Pentax lens. Those lenses will NEVER work again on a Pentax, since they remove the diaphragm actuator to use them manually. The reason you can mount a Pentax lens on a Canon is due to the fact that the registration distance on the Canon is shorter than the Pentax (the distance between the sensor plane and the bayonnet outer face).

There are adapters out there for Pentax lenses to Canon camera, and to Olympus too. No need to wreck the lens to get it to fit.

It could have been an M42 screw thread lens, for which mount adapters can be found to use them on quite a wide variety of cameras. In any event, it's usually worth a chance if the price is low enough.

well if you're gonna put it on a canon, why not wreck the lens?

You may find that M42 lenses don't meter properly on the K-x, I know they don't work on my K-m even with the genuine adapter. I've tried all combinations of settings and they always end up seriously underexposed.

There is a solution if you want to enjoy the SMC Takumar brilliance on a K mount without an adapter - buy the original SMC Pentax (sometimes called K series) lenses. These will still embarrass modern glass with a bit of skill on the part of the user - I have the 28mm f3.5, 55mm f1.8 and 120mm f2.8 along with a couple of zooms. The 28mm and 55mm are sharp enough to shave with wide open and just get better as you stop down.

There are essentially three types of K mount lens. The all manual ones like the K and M series (SMC Pentax or SMC Pentax-M) which will fit but are manual focus and will need you to use stop-down metering in Manual mode. The A series (sometimes called PK-A fit by 3rd parties) which will work in all exposure modes but are still manual focus, and the auto focus ones which work just as your DA lens does.

Stop down metering isn't hard to use, and some of the old K or M lenses make it very worthwhile. If you see a K or M 28mm f3.5 for £50 or less in good condition then buy it, you won't regret doing so.

Do beware lenses with the Ricoh pin - this is in roughly the same location as the AF drive screw on your kit lens and as a result jams in the Pentax AF drive making it impossible to remove the lens. Some other brands also fitted this infernal device - I have a Tokina PK-A fit 28mm and a Jessops-branded teleconverter with them, although both of those have a rounded pin which doesn't seem to cause any trouble. Yes, I did try them on my spare MZ50 body first to make sure it wouldn't jam the K-m!

As a newbie you'd probably be best sticking with the "A" lenses, if your unsure look closely at the lens mount for the electrical contacts.

Genuine Pentax "A" lenses will command a good price but there are some third party bargains around even in AF.