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07-28-2012, 06:11 PM   #1
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Converting m42 to Pentax K with flanged adapter

Or should I use an non-flanged adapter, I couldn't find any pics or tutorials, so who has done the conversion and what are your suggestions? Ultimately what I am after is a lens that goes on and off the camera like a K or M series lens and not having to unscrew the lens then take the adapter off the camera in 2 steps.


Last edited by littledrawe; 07-28-2012 at 06:21 PM.
07-28-2012, 06:17 PM   #2
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With a flanged adapter you will lose infinity focus. Use a generic non-flanged adapter with the sping clip removed.
07-28-2012, 06:33 PM   #3
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QuoteOriginally posted by boriscleto Quote
With a flanged adapter you will lose infinity focus. Use a generic non-flanged adapter with the sping clip removed.
With that do I need to drill into the base of the lens to create a depression to accept the lens release pin?
07-28-2012, 06:58 PM   #4
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QuoteOriginally posted by littledrawe Quote
With that do I need to drill into the base of the lens to create a depression to accept the lens release pin?
You would, if you want it to "click" into place like other k-mount lenses. That's one advantage of the flanged adapters, and why I use them (with red Loctite) on my Russian portrait glass!

07-28-2012, 07:00 PM   #5
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They are called adapters for a reason -- you don't need to alter or convert the lens. These adapters are generally designed to be put on the camera, not the lens -- they turn your camera into a m42 mount. Nevertheless, the flanged adapters are very easy to deal with because they don't have those infernal spring locks, you just screw them on -- they work quite well on the lens instead of on the camera (a spare bayonet rear cap is good to have to get them off the lens). With the non-flanged adapters that allow infinity focus, unless it is a genuine Pentax one, the first thing you should do is remove the spring lock. Now it is suitable to put on the lens rather than the body, but be aware that nothing will lock it onto the body, it will just be a friction fit.
07-28-2012, 07:05 PM   #6
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If the flange is on the inside--it is supposed to close down lenses which don't have the ability to be put into manual (e.g., vivitar T4 lenses)--that is a benefit--except the one I tried was improperly made (oversize/too thick coating?) and was too tight.

If the flange is on the outside then it will not focus to infinity as was mentioned above.

I recently got a couple of pentax adapters from pentax directly, and I think it was about $50.00 for both--the point is they were pretty cheap and other adapters can be a source of grief--do a search on M42-K adapters and you will hear lots of sad tales.
07-28-2012, 07:11 PM   #7
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And yes, for not too large lenses I remove the spring from the pentax adapter and leave it on the lens. But well above 50 mm, it starts to be problematic as the lens can start to unscrew as you change focus or aperature. Anyway I have this problem with both my 200mm takumars (f/4 and f/5.6). Some will say removing the spring means you can use 3rd party adapters--and if you have many lenses that is likely best--but with only one or two I prefer to be safer and use Pentax adapter.
07-28-2012, 07:34 PM   #8
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QuoteOriginally posted by panoguy Quote
and why I use them (with red Loctite) on my Russian portrait glass!
I like that idea!

QuoteOriginally posted by vonBaloney Quote
but be aware that nothing will lock it onto the body, it will just be a friction fit.
That is what I don't want.

07-28-2012, 08:01 PM   #9
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QuoteOriginally posted by littledrawe Quote
That is what I don't want.
The problems is that with the non-flange adapters with the spring they can jam in the camera and it can be VERY difficult to remove them. That is why people are saying to remove the spring clip before you install them.
07-28-2012, 09:20 PM   #10
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I was saying that I don't want it to be a friction fit like vonBaloney mentioned, the spring on the adapter is a PITA and I would like to not have to deal with that so I will try the flanged adapter and see where that gets me. I want the lens to stay on with the assistance of the locking pin so its flanged adapter or no flange and cut into the lens for a depression to accept lens release pin.
07-29-2012, 06:45 AM   #11
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With most lenses the friction fit is still quite a lot of friction -- it is pretty secure. The genuine Pentax adapters are made to be a bit loose in the camera actually -- those are better for leaving on the body (and they are much easier to remove than the third-party ones). But if you want it to lock, you lose infinity or you screw the lenses on and off like it is a native screw mount. I use them every which way and have no troubles except with one lens and I just found a solution for that yesterday.

The lens in question being a Meyer Optik Orestegor 200mm f/4 which has a base that tapers down at the screw mount so there is no overlap on the body -- the Meyer 135 is also like this and also the equivalent Pentacon versions. This is no problem for a flanged adapter because those lock down and the Pentax adapter works but there is a bit of play which is annoying when focusing. Using a third-party adapter there is no friction other than at the adapter level and it isn't quite enough -- the lens/adapter tends to rotate when focusing and even had a light-leak where I took out the spring lock. Solved it with a big rubber washer for $1.49 from ACE hardware. It was slightly too small for the hole (which is good cause I want it tight) -- I pulled it on with needle-nose pliers and then screwed adapter on the lens -- the washer flips up onto the tapered lens base but leaves enough of an edge to provide a lot of friction to the camera body. Now it has a bayonet that as secure as any other lens (and no light leak). But I can still take it off in a few seconds if I want and didn't have to drill or file anything. And I'm very happy to have found a way to get this one secure as I really like this lens and I've got my eye on the 135 with the same design.

But most lenses work fine with a friction fit -- the third-party adapters have more friction to begin with. I'm using a "Roxsen" from ebay -- works good. I've tried others where the lens ended up upside-down when screwed in.

Last edited by vonBaloney; 07-29-2012 at 07:17 AM.
07-29-2012, 07:05 AM   #12
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QuoteOriginally posted by littledrawe Quote
I was saying that I don't want it to be a friction fit like vonBaloney mentioned, the spring on the adapter is a PITA and I would like to not have to deal with that so I will try the flanged adapter and see where that gets me. I want the lens to stay on with the assistance of the locking pin so its flanged adapter or no flange and cut into the lens for a depression to accept lens release pin.
At one time, I considered esetting the infinity focus of my lenses and using flanged adaptors on every lens, because they are cheap. But with time, and the failure of the lens licking pin on my K10D I have just left the M42 adapter I the K10 and I use it now exclusively with screw mounts
07-29-2012, 07:29 AM   #13
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Friction fit

I've found that if you "smudge" * a very little bit of silicone sealer on one surface and let it set up you can gain just enough friction to feel secure with the non-locking lens adapters and overcome the focusing torque. This is slightly less "sticky" than the weakest strength Lock-tite.

Experiment with the sealer between the lens and adapter to get a feel for what would work between the adapter and camera mount. The sealer does NOT need to cover the entire mount or include the data pin area to be effective and should be dry to prevent smearing it onto the pins.

If you need to remove (or adjust) the amount of sealer you can later scrape it off with a razor/Exacto blade or similar.

* smudge = about what would be a messy finger print on the lens glass. Try it on a water glass.

H2
07-29-2012, 12:00 PM   #14
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QuoteOriginally posted by vonBaloney Quote
I've tried others where the lens ended up upside-down when screwed in.
It would be nice if they would at least cut the threads right to prevent that from happening!!

QuoteOriginally posted by pacerr Quote
I've found that if you "smudge" * a very little bit of silicone sealer
I may just give that a shot depending on how stiff the focusing is on the lenses.
07-29-2012, 04:59 PM   #15
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QuoteOriginally posted by littledrawe Quote
It would be nice if they would at least cut the threads right to prevent that from happening!!


I may just give that a shot depending on how stiff the focusing is on the lenses.
If you have not yet tried any of these, I'd put aside all these thoughts of special mods until you actually see what you are dealing with. They are generally not needed...
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