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01-02-2010, 10:43 AM   #1
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M42>K adapter that stays on lens........

There are times when I want to QUICKLY change from a K-zoom to one of my M42 primes and change back after. Does anyone have recent experience with the adapters currently on ebay? Or one of the retail sites?

Just to limit the responses to those that are relevant:

1. I have a Pentax adapter (somewhere) that I could use if I was only shooting M42.

2. No, it doesn't take that long to change the adapter but I don't like fumbling around with a bunch of different things when I'm in a hurry. I can be clumsy and then it is one more thing to keep track of.

3. I won't be drilling holes in the lens (like Hinman) but the lenses I'm using are heavy and I will have one hand on them at all times so the lack of a locking pin is not critical. (Vivitar S1 135/2.3, 200/3, 90/2.5 Macro, and 70-210/3.5)

4. I really want infinity or near infinity focus.

5. I would use a bit of the removable Loctite on the threads to secure the adapter.


01-02-2010, 11:18 AM   #2
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There are non-flanged adapters that allow infinity focus on ebay. (Write "Pentax m42 adapter infinity" in the ebay search function. Here's an example.) They have a locking mechanism which can be easily removed--I don't like to use the weird metal device that comes with it to take it out of the camera. I used a drop of glue to stick such an adapter to my 55mm 1.8 Takumar, which now functions as a K mount (without lock, however).
01-02-2010, 01:01 PM   #3
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That is one of the adapters I was looking at and just wanted some feedback of people who had actually used them this way. I love using these old lenses but hate constantly having to swap the adapter in and out.

Maybe someone needs to come out with a digital equivalent to my old Chinon CE-3 or the Spotmatic F...........
01-04-2010, 03:06 PM   #4
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I use one of the cheap infinity mounts with a 400mm lens that weighs loads and have no problems with it. Of course I took off the locking spring and so far it holds the lens in place just fine.

I had a nightmare with the first one that I bought because I didn't take the spring off and I could not get it out of my K20D. I ended up prying it out with a screwdriver and hoping for the best. Thankfully nothing was damaged.

If you get one, TAKE OFF THE SPRING!!! It's only held on with a small phillips head. I have heard though, that some people have had heavy lenses fall off in this configuration. I, however, have had no problems.

01-07-2010, 08:14 PM   #5
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The Bower is the one to remove the spring clip to accomplish this. I used one on my smc Tak
300/f4 and it works great. The bower is the one that has the goofy looking key to remove it.
01-07-2010, 08:35 PM   #6
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The ear of the Pentax brand adapter shown on the left has square corners at its root, whereas the non-Pentax brand adapter shown on the right has a rounded root. The square corner helps prevent the Pentax adapter from over-rotating when you mount the lens.

A notch for the locking pin in the lens base will also pervent the lens from over-rotating when mounted (over-rotating is a far bigger threat than the lens' falling off during use.) If the lens over-rotates, don't panic. It'll come off by rotating it in either direction.
01-07-2010, 09:33 PM   #7
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Interesting. I never thought about over-rotation being a problem. If the problem is the rounded cut, a little judicious file and stone work should solve that problem.
01-15-2010, 06:54 PM   #8
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Echoing some of the above - I use all three types of PK-M42 adapters:

1) official Pentax infinity-focus - it stays on the K20D or ZX-M on days when I'm mounting only M42 glass, and maybe carrying another M42 body.

2) generic non-infinity focus - they stay on old telephotos that focus past infinity, and on glass for close-up or portrait use, and on an M42 bellows.

3) Bowers infinity-focus - they stay on my most-used M42 glass, AFTER the (sucky) locking springs are removed. I hate those (expletive deleted) keys.

Also, during my eBay spree days, I ordered two sets of (manual) macro rings, and was shipped four sets. I've put those extras to good use. The PK-mount sections are good for mounting really odd lenses, for when I want those Holga-oid headache effects. Plastic lenses, eyeglass lenses, odd stuff from Edmund Scientific, whatever. Groovy!


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