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...
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Pentax *ist DL | Pentax K200D | Pentax Program A | Pentax Spotmatic SP | Pentax ME Super | Pentax SF7 | Olympus OM2 | Cosina 1000S | Ricoh Singlex TLS | Praktica EE2 | Zenit-E || Olympus Trip 35 | Olympus Trip 35 || Petri MC Macro 24mm f/2.8 KA | Takumar-A Zoom 28-80mm f/3.5-4.5 KA | Super Takumar 50mm f/1.4 m42 | SMC Pentax-M 50mm f/1.7 K | Pentacon (not so) Electric (anymore) 50mm f/1.8 (m42) | Domiplan 50mm f/2.8 m42 | Olympus F.Zuiko S 50mm f/1.8 OM | Auto Revuenon (Tomioka) 55mm f/1.4 | Cosinon Auto 55mm f/2.8 m42 | Auto Rikenon 55mm f/2.8 m42 | Helios-44-2 58mm f/2 m42 | Jupiter-9 85mm f/2 (1971) m42 | Auto Petri 135mm f/2.8 m42 | Hi-Q 135mm f/3.5 T2/m42 | Jupiter-11 135mm f/4 m42 | Jupiter-11A 135mm f/4 m42 | Takumar-A Zoom 70-200mm f/4 KA | RMC Tokina 70-210 f/3.5 K (same as Vivitar Series 1 model 2) | Sun Auto Zoom 85-210mm f/4.8 m42(ish) | Kenlock 500mm f/8 T2/m42 || Weltblick auto 2x tele converter m42

[peterqd]

How about using K-mount extension rings with the M42 adapter at the front end?
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Lenses: M42 - CZJ 2.8/20, 2.4/35, 1.8/50, 2.8/50, 3.5/135 - Meyer/Pentacon 1.8/50, 2.8/50, 2.8/135, 4/200
Russian - J9, J21, J37A, M1v, M24m, I50-2, H44m-4 Vega12
Takumar 3.5/28, 2.0/35, 3.5/35, 1.4/50(x2), 1.8/55(x2), 1.9/85, 3.5/135 - Vivitar 2.8/28
K-mount : Pentax-M 2.8/28, 1.7/50 - Tamron zooms :SP28-80, SP35-80, SP60-300, 80-210
DSLR:Canon 400D 35mm SLR: Pentax Spotmatic SP, SPII(x2), SPF, ESII, K2, ME Super, P30 - Chinon CE3 - Minolta XG-M - Praktica Nova 1B, PLC2
Rangefinder: Zorki-4, Beauty Light-o-matic III Medium Format: Yashica-Mat 124G

[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.
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My Flickr - Takumar.org
PENTAX K10D, Spotmatic
Asahi Auto Takumar 85/1.8
Asahi Takumar 105/2.8 135/3.5
Asahi Super Takumar 20/4.5 50/1.4 55/1.8 85/1.9 105/2.8 135/3.5 150/4 200/4
Asahi S-M-C Takumar 35/3.5 300/4
Asahi S-M-C Macro-Takumar 50/4,100/4