best m42 extension rings for use with K->m42 adapter?

[pixelbart]

Hi all,

I have a little problem with almost every m42 extension ring I can find on my Pentax dSLR's. Let me explain.

The m42->K adapter fits inside the K-mount like this:


(fyi: that's a Super-A/Program-A)

It has some margin, so a lens that only touches the adapter isn't very stable. A lens needs to be wide enough to push against the K-mount to be firmly attached to the body. For a normal lens this isn't really a problem because it's back plate is usually wider than the m42 adapter:




Most extension rings, however, are a lot narrower, so they only touch the adapter:



I discovered that this causes some vibration blur almost always with long exposures, even with 2s self-timer, a good tripod, a concrete floor and me sitting as still as possible.

Does anybody know about m42 extension rings with a wider base, so they are more firmly attached to the K body? I've already thought about taking a (wide enough) m42 tele converter and removing the lenses from it, to use it as the first extension ring, but the only m42 teleconverter I have is also too narrow...

[peterqd]

How about using K-mount extension rings with the M42 adapter at the front end?

[pixelbart]

[zewrak]

I use Pentax own rings and it works well. The black ones that looks like Super Taks. :p So, yes, probably Asahi made rings.