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12-23-2010, 04:36 PM   #1
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M42 to K-mount instructions: link?

Sorry for asking what is probably a common question, but I remember seeing somewhere detailed illustrated instructions on converting an M42 lens to K-mount by removing the spring from the Pentax adapter, then dremeling a shallow hole in the lens flange so that the lens would lock in place when mounted. Can somebody point me in the right direction?

Also, what's the skinny on shorting the contacts? Does this need to be done? I'm talking about a 50/1.4 SMC Tak.

Much appreciated, in advance.

12-23-2010, 04:45 PM   #2
Ole
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Here you go:

Genuine Pentax Screwmount Lens Adapter

No, you need not short any contacts. Just mount the adapter on the lens, bayonet the combo into the camera and go shoot in either Av or M exposure mode!

Ole
12-23-2010, 04:51 PM   #3
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Thanks! Yes, I have the adapter and those instructions...I'm most interested, however, in doing the modifications that allow the adapter to remain on the lens semi-permanently, so that it can be bayoneted on and off the camera just like a K-mount lens. This involves drilling a small shallow hole for the locking pin to engage, and I want to make sure I do this properly.
12-23-2010, 05:14 PM   #4
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Try it without drilling the hole first, I removed the lock from the adapter and always
put the adapter on the lens first. Find it easier than threading onto the camera.
Unless the focus is very stiff the lens should not turn.
The only lens that this does not work with is my Helios 44-2 as the base is narrower than
the adapter. Made up a special locking plate for that one.

12-23-2010, 05:15 PM   #5
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OK, I'll try that first!
12-23-2010, 05:50 PM   #6
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QuoteOriginally posted by mabelsound Quote
Thanks! Yes, I have the adapter and those instructions...I'm most interested, however, in doing the modifications that allow the adapter to remain on the lens semi-permanently, so that it can be bayoneted on and off the camera just like a K-mount lens. This involves drilling a small shallow hole for the locking pin to engage, and I want to make sure I do this properly.
I would try a product referred to as "Threadlock"... they come in different strengths and your local hardware store should have it... I would try this before drilling... threadlock can be loosened by heat or shear force but the force needed is much more than force needed to mount and unmount your lens...

Good luck - Rick
12-23-2010, 06:45 PM   #7
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I have a couple dozen cheap Bower-type M42-PK adapters residing on some of my 100-odd M42 lenses. My practice is to 1) remove the screw and spring/clip from the adapter so that I DON'T GO APESHIT TRYING TO REMOVE ADAPTER FROM CAMERA! and 2) use a PK rear lens cap as a wrench to tighten the adapter onto the lens. Use the rear cap to loosen and remove the adapter when desired, also. This technique save fingertips and other fleshy bits. I've had some lenses so adapted for so long that I've almost forgotten they're not native K-mount.

If the lens has a wide enough base to cover the mount, some tinkerers take an extra step and cut a small groove in the base, about 2mm wide and deep and as long as is necessary, that the camera mount's locking pin can engage. I have yet to do this with my adapted M42's and my modded OM's, C/Y's and Nikons, but I should, yes I should...
12-24-2010, 06:24 AM   #8
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QuoteOriginally posted by RioRico Quote
I DON'T GO APESHIT TRYING TO REMOVE ADAPTER FROM CAMERA!.
YES indeed!!!

12-24-2010, 06:31 AM   #9
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The problem isn't the lens coming unscrewed from the adapter--that is generally more than secure enough, as secure as any screwmount lens on a screwmount camera. It's that the adapted lens does not lock in place the way a K-mount lens does--you don't need to press the release button to unmount it. If the focus is stiff, the lens can come loose from the camera while you're shooting. "Threadlock" doesn't address this problem--but as bobpur says, perhaps it's less a problem than I think.
12-24-2010, 06:41 AM   #10
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QuoteOriginally posted by mabelsound Quote
The problem isn't the lens coming unscrewed from the adapter--that is generally more than secure enough, as secure as any screwmount lens on a screwmount camera. It's that the adapted lens does not lock in place the way a K-mount lens does--you don't need to press the release button to unmount it. If the focus is stiff, the lens can come loose from the camera while you're shooting. "Threadlock" doesn't address this problem--but as bobpur says, perhaps it's less a problem than I think.
100% Agree!

The thread lock should keep the adapter on the lens w/o modifying lens or adapter but doesn't address the issue of lens/adapter actually locking into place. I use the Original Pentax Brand m42 adapters and never have problems removing from camera body. I've got a couple of heavier m42's and I think w/o the locking mech in place I would accidentally unmount theses lenses while zooming or focusing, and you know might happen next...
12-24-2010, 07:03 AM   #11
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QuoteOriginally posted by theunartist Quote
100% Agree!

The thread lock should keep the adapter on the lens w/o modifying lens or adapter but doesn't address the issue of lens/adapter actually locking into place. I use the Original Pentax Brand m42 adapters and never have problems removing from camera body. I've got a couple of heavier m42's and I think w/o the locking mech in place I would accidentally unmount theses lenses while zooming or focusing, and you know might happen next...
OK, so how do you get them to lock? Do you drill a hole on the flange, or is there some other method?
12-24-2010, 08:30 AM   #12
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I used a dremel, look at one of your k-mount lenses for location of the dimple, then make a small indent in the metal of the lens, use threadlock/superglue to get the adapter to stay on, and your lens is now k-mount and you will hear a click when you mount it. Oh and if you size your drill bit (that you will attach to a demel (or drill press/ drill for that matter) to be the same size as the hole in your k-mount lenses then it will feel exactly the same way.
12-24-2010, 08:33 AM   #13
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Drill a hole where the locking pin goes - if you press the release button for the lens on the camera body, you can see the locking pin move in and out. You just need to drill a small hole in the adapter for that pin. Then you can remove the spring that locks the adapter onto the camera body.
12-24-2010, 09:14 AM   #14
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Perfect. Just examined one of my FA Limiteds...it is very clear where the depression should go. Thanks!
01-05-2011, 07:14 AM   #15
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I transformed my Helios 40-2 85/1.5 to Pentax K mount exactly the same way. if you wish to read, find more here
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