[jheu02]

This adapter came with a set of extension tubes and I wondered if anybody had some info on them. As the pics show, it's a 2-part adapter with 3 set screws for the inner ring. The inner ring threading does measure 42mm, so it's obviously designed for M42 thread. With the inner ring out, it measures 50mm across. There's no aperture lever and it's much thicker than the standard M42 to P/K metal ring. Since I don't have any M42 lenses, I can't play around with it to further test it.

[bobpur]

You have a T2 mount to PKthe threads are not M42 ,same size but finer threads.
The 3 screws are to allow the alignment of the lens ( F mark and focus marks Up )
then you tighten them.
Keep it you can easily convert a lot of old M42s to Pk with it.

[jheu02]

You have a T2 mount to PKthe threads are not M42 ,same size but finer threads.
The 3 screws are to allow the alignment of the lens ( F mark and focus marks Up )
then you tighten them.
Keep it you can easily convert a lot of old M42s to Pk with it.

Thanks for the info, but if the threads are finer than M42, how do you say I can easily convert a lot of old M42s to P/K?

[Lowell Goudge]

the way to mount M42 lenses on to your K body is with an M42 to K adaptor.

this is specifically made for pentax(and others) screw mounts and accepts the M42 by 0.75mm pitch thread of the lenses

The T mount adaptor is used to convert lenses made for Tmount with M42 x 1 threads to any lens mount, you just happen to have the K version.

DOn't get rid of it, it will come in handy when you go shopping for preset lenses with 15-20 aperture blades because most of them are T mount.

There is a thread

https://www.pentaxforums.com/forums/pentax-camera-field-accessories/96884-ada...addiction.html

Which really should be a sticky that addresses all types of adaptors

[jheu02]

Thanks. Just so I'm sure I understand, though the little inner ring says P/K, it is still the T-Mount 42mm x 0.75 vs M42 threading (i.e. they just printed the P/K on that side of the adapter vs near the bayonet parts).

Next question: I was doing some more research on this and also came across some T mounts that said T-50. Would this be usable without the inner ring for mounting a T-50 lens to my K20D? Also, is this usable with T4 lenses or is that a different adapter altogether as that has auto-aperture correct?