[surfmanjoe]

My friend has a old K mount 50mm F1.2, I like its performance. but NOT sure if it may sit on K-X dslr， I have not had any pentax body, neither my friend.

So my question is

1) will K-X or K-7 work well with this lens?
2) will any of body have focus indicator showing correctly focused for this lens?

Thanks.

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Last edited by surfmanjoe; 07-21-2010 at 06:25 AM. Reason: typo, should be K mount, NOT M mount

[ChooseAName]

If the 50 mm f/1.2 fits on any Pentax, it will fit on the K-x. As long as the lens is good, yes, the K-x or K-7 will work fine with it, although you will have to shoot in full manual. I am not certain if the focus indicator will work. It will if you use catch-in focus, which I'm not sure if the K-x or K-7 has that feature.

[urje]

If the term 'M mount' is accurate, I suppose that means it's a leica M-mount lens, meaning it won't work, because the registration distance (from mount to sensor) is much larger in Pentax SLRs than it is in Leica rangefinders. However, Pentax has made 'SMC Pentax-M' lenses for decades, so in the case that is what you refer to, it would fit on K-x as well. In that case, it doesn't really have an 'M mount', but a 'K mount'. Unfortunately I'm afraid you're out of luck: as far as I know, Pentax did not make an f/1.2 lens in their 'M' series.

[Marc Sabatella]

See the sticky thread at the top of the Beginner's forum for info on how to use full manual lenses on a modern DSLR. But note as the previous poster says, it appears you might be confused, as there is no "M mount" for Pentax - only M42 and K-mount. K-mount lenses mount directly; M42 lenses work but require an adapter. Pentax has a series of lenses marked "Pentax-M", but the mount is K-mount, and there is no 50/1.2 in this series. It seems likely to me that what your friend actually has is a 50/2, as they are marked 1:2 (quite distinct from 1.2)! The M50/2 is an ok lens, sold in most pawn shops for $10 or so. The f/1.2 lenses (again, none in the "M" series) are much more expensive and rare. If it really is "M mount", that is indeed Leica, not Pentax.

Anyhow, assuming it really is K-mount - or M42 but you get an adapter - it will work as described in the thread I mentioned, and focus confirmation does work. it's not normally as fast as convenient as focusing with your eyes, but it does work.

[KxBlaze]

Unfortunately I'm afraid you're out of luck: as far as I know, Pentax did not make an f/1.2 lens in their 'M' series.

Correct, but Pentax did make a 50mm 1.2 in their K series lenses, so it is still very possible that this lens will mount on a Kx or K7.

If your friend has a Pentax (any Pentax camera) then it will definitely fit on a Kx or a K7. If you do attach the lens make sure you set the camera to "Permit Aperture Ring" and that you are in full Manual mode, otherwise you will see a "F---" where the aperture should be.

And yes the focus indicator on both cameras should work just fine for that Kseries lens (if it is a Kseries lens).

[Pentaxor]

the misconception starts when the letter "M" is thought to be manual K mount lenses.

[KxBlaze]

The OP never mentioned anything about an "M" mount., so I don't know why people are saying M mount. The OP says the lens is K mount and since its a 1.2 I'm assuming that it is the SMC (K series) 50mm 1.2, which will mount just fine on any Pentax camera.

[Adam]

The OP never mentioned anything about an "M" mount., so I don't know why people are saying M mount. The OP says the lens is K mount and since its a 1.2 I'm assuming that it is the SMC (K series) 50mm 1.2, which will mount just fine on any Pentax camera.

It's still in the thread title

Yes, the Pentax Lens Review Database - SMC Pentax 50mm F1.2 Lens Reviews will work with the Pentax K-x (as well every other lens listed in that database).

[urje]

well yes they did, but they edited that after my post.