[rcolman]

I purchased a rthter nice Super-Takumar 200mm F4 at a local photo show for an attractive price. It is super-clean, both the metal body and the interior glass.

I did a little "star-testing" this evening on a K-1 body, and, not too bad !!

However, I noticed that the mount adapter did not seem to be giving me a positive connection on the bayonet side - no click or lock - and if I am not careful, I can accidentally start unscrewing the lens .... obviously I have little experience with screw mounts ...

I am beginning to think I have the wrong adapter.

I purchased a Fotodiox m42 to pentax K adapter.

Is this the wrong one?

tnx for any advice.

-- rick

[Adam]

That's pretty much how screwmount lenses are, that said, you'll probably get a tighter fit with the genuine adapter, which I'd strongly recommend if you plan on using a lot of M42 lenses.

https://www.bhphotovideo.com/c/product/673977-REG/Pentax_30120_MOUNT_ADAPTER_K.html

[stevebrot]

However, I noticed that the mount adapter did not seem to be giving me a positive connection on the bayonet side - no click or lock - and if I am not careful, I can accidentally start unscrewing the lens .... obviously I have little experience with screw mounts ...

Your Fotodiox adapter should click into place. Unscrew the lens to remove it from the adapter. Removing the adapter from the body often requires the included tool and sometimes may be very difficult/impossible even with the tool. As Adam noted, the original (and more expensive) Pentax adapter is strongly recommended over third party options.


Steve

[stevebrot]

However, I noticed that the mount adapter did not seem to be giving me a positive connection on the bayonet side - no click or lock - and if I am not careful, I can accidentally start unscrewing the lens .... obviously I have little experience with screw mounts ...

Your Fotodiox adapter should click into place. Unscrew the lens to remove it from the adapter. Removing the adapter from the body often requires the included tool and sometimes may be very difficult/impossible even with the tool. As Adam noted, the original (and more expensive) Pentax adapter is strongly recommended over third party options.


Steve

[marcusBMG]

FYI

https://www.pentaxuser.com/forum/topic/m42-pk-adapters---some-personal-experiences-36409

[UncleVanya]

An approach some use is to get a cheap adapter PER m42 lens and use thread locker (the kind that is removable) on the adapter and lens and thus create a quasi-K mount with each of them.

[rcolman]

An approach some use is to get a cheap adapter PER m42 lens and use thread locker (the kind that is removable) on the adapter and lens and thus create a quasi-K mount with each of them.

So, here is the problem with all this stuff. I want to take astrophotos, where small differences make a difference. Last night, without a positive "clkick" into the bayonet mount, there is always some danger of wiggling around.

So, regardless of whether I thread lock the scew, etc. I still need a positive attachment to the bayonet mount, and this is not happening !

[stevebrot]

So, regardless of whether I thread lock the scew, etc. I still need a positive attachment to the bayonet mount, and this is not happening !

Your adapter is supposed to have a spring-metal clip that locks it in place in the mount. Ideally, the adapter should still be a little loose when a lens is not in place. The mount face on the M42 lens is supposed to engage the face of the K-mount to provide both stability and lens registration.

If your adapter rotates out (disengages from the mount), I suggest you send it back as defective and order the genuine Pentax version as suggested by Adam (above). This advice comes from a user who came up short with a Bower-branded adapter sold by a major online retailer and who will never use a third-party version again.*

BTW...my genuine engages the mount quite securely with a definitive "click".


Steve

* ...with possible exception of the SRB Griturn product, which reportedly are made by SRB to be a close copy of the genuine

[stevebrot]

there is always some danger of wiggling around.

BTW...I don't believe there is a problem with any Asahi or other Japanese M42 lenses, but some German and Soviet-made M42 lenses have narrow diameter mount faces. As a result, the lens does NOT engage the mount face on the body. The result is a lens that "rocks" side-to-side on the camera even when properly used with the genuine adapter. Users on this site have compensated for this incompatibility by using rubber gasket rings or rubber o-rings to bolster the lens to the mount face.


Steve