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08-21-2009, 11:13 PM   #1
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2 different M42 to K-mount & genuine Pentax one

I’m trying to permanently convert some of my favourite M42 lenses to K-mount.
(with infinity focusing of course)
Genuine one on eBay goes for $60 plus, and I need 3-4 of them.
That’s why I decided to go for aftermarket around $16 with postage.
I did purchase from eBay two different adaptors which looks very similar to the original one.
They come with a special tool that allows removal from the camera body but that won’t bother me as I will never use it and only remove the little spring and use this adaptor permanently on my M42 lenses.
None of them will allow me to mount any of my M42 lenses on any of my Pentax body (ME Super, P30, Super A, PZ1p, or K20D.
First one I did sent back (some 3 months ago) so the seller could check if it is faulty and send me another one to refund me, (till this day nothing….. not a pip).
The second one I received today from different eBay seller, same story.
I did try everything, seems like it should work but it doesn’t.
When I put this adapter on any of my M42 lenses it just won’t mount on any Pentax body (I have no problem with my original Pentax adaptor).
However if I try to put this adapter by it self to a camera body (without lens), it clicks in position OK.
I checked the thickness of both adapters and the genuine Pentax is 4.92mm where the aftermarket is 4.87mm, so looks like this could be the only reason, also you can notice on the pictures that they are a slightly different shape (on the edges).
I hope some one could point me in the right direction where I can find an aftermarket adaptor which will allow me to convert my lenses from M42 to K-mount.

Pictures of adapters:
genuine Pentax adaptor on left and two aftermarket on right.

Cheers
Greg

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08-22-2009, 12:44 AM   #2
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No need to convert your M42 lenses, just have that genuine Pentax adapter in when you are using M42s. The el cheapo copies can cause grief when the spring plays up and the flanged adapters screw up infinity focus.
08-22-2009, 12:56 AM   #3
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QuoteOriginally posted by xjjohnno Quote
No need to convert your M42 lenses, just have that genuine Pentax adapter in when you are using M42s. The el cheapo copies can cause grief when the spring plays up and the flanged adapters screw up infinity focus.
I agree with you absolutely no flange.
The spring from the adaptor will be removed before being permanently mounted on M42 lens, that will make a normal K-mount lens.
My point to all this excise is that I would like to speed up the changing of the lenses and at the same time cutting the possibility of dust entering my K20D.
08-22-2009, 01:48 AM   #4
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I agree with xjjohnno, just use the original. You'd hae to drill a locking pin slot in the back of each lens for it to lock in place. Otherwise you risk turning the lens right off the camera when adjusting aperture or focusing. You could easily drop the lens.

If you look closely at the aftermarket mounts, the tabs are thinker and that is most likely why you can't get them on with the lens attached. The only cheaper adapter I've used that is OK (but not as good as the Pentax) is the Bower version.

But really if you are a little careful, Dust is not an issue and you can replace lenses quite quickly with M42's

08-22-2009, 05:33 AM   #5
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I have one of the super cheap eBay ones without the flange on my 55mm Tak. What I ended up having to do is make a ring of solder to go between the adapter and the lens. NOT hot solder, just a string of cold solder wire, the skinny variety. It compressed just enough to allow for infinity focus. The only drawback is the lens is ~80 degrees rotated from where it should be. It's not really a big deal to me because I leave my lenses on "M" all the time anyway.

By the way, you can buy the "real" adapter straight from Pentax for roughly $30.
08-22-2009, 05:51 AM   #6
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QuoteOriginally posted by Peter Zack Quote
....
If you look closely at the aftermarket mounts, the tabs are thinner and that is most likely why you can't get them on with the lens attached.
....
Yes. A circular gasket of cardboard or wire will probably make the flange thick enough.

Use a file to "square off" the fillets on the bayonet ears of the adapter; the photo shows a Pentax adapter on the left & a clone on the right. This helps prevent over-rotation. Or drill an indent in the lens' base to lock the lens into position.


Dave
08-22-2009, 08:31 AM   #7
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QuoteQuote:
You'd hae to drill a locking pin slot in the back of each lens for it to lock in place. Otherwise you risk turning the lens right off the camera when adjusting aperture or focusing.
also, not every m42 lens has a base that is wide enough for this to even work. in fact id go so far as to say that for 70+% of Takumar lenses, this wont work.

there is no proper solution for using m42 lenses on a Kmount body and have the same convenience as you'd have using Kmount lenses.

if you want the convenience of using Kmount lenses,,, well then use Kmount instead of m42, period. pretty much every Takumar can be replaced with a K,M or A equivalent, so why spend money on so many adapters, and turn to cosmetically damaging your lenses in an attempt to gain the convenience of lenses that you can have without doing any of that?
08-22-2009, 02:35 PM   #8
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The adapters (especially the cheep ones) are made with a thinner flange intentionally. They are designed to be mounted on the camera before the lens is screwed on so that it tightens against the metal lens bayonet on the camera and removes all slack from the system. If they were made so that they could be fitted straight onto any M42 lens then the most lenses would end out lose due to the tolerences.

The cheep flanged adapters that I got were quite accurate and had very little play. Unfortunately, only longer focal length lenses are likely to have enough adjustment in the focus helix to alow the infinity focus to be adjusted to compensate for the flange thickness. So far the only one of mine that has been converted is the Super Tak 300mm f/4 which has just enough focus adjustment.

In another thread ( https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/68480-infinity...42-lenses.html) it has been sugested that flanged adapters can be modified to fit M42 lenses whilst preserving infinity focus by machining / sanding them down to the apropriate thickness. I havent tried this yet but I intend to, although I suspect that they will have to thined quite accurately to get infinity focus and fit without too much play.

QuoteOriginally posted by séamuis Quote
so why spend money on so many adapters, and turn to cosmetically damaging your lenses in an attempt to gain the convenience of lenses that you can have without doing any of that?
Because M42 lenses are cheeper, plentiful and can take photos of comperable and sometimes better quality than K mount lenses. It can be quite satisfying modifying them and with care some conversions can be made completely reversibly.

08-22-2009, 09:25 PM   #9
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I just want to say thanks a lot to everyone, for giving me all this great advice.
I did try all suggestions from MattGunn, Steve Beswick and Newarts and everything made sense and of course works
I will try the adaptors with flange as well ( as soon as I get them) and test some of my longer M42.
I will make sure that none of my lenses will be damaged in any way.
I will not drill a locking pin slot in the back of each lens for it to lock in place as I reckon it is not necessary, I will check this out anyway.
Thanks MattGunn for the link, and you absolutely right saying that
Quote: "M42 lenses are cheaper, plentiful and can take photos of comparable and sometimes better quality than K mount lenses. It can be quite satisfying modifying them and with care some conversions can be made completely reversibly."

I believe that some of the M42 primes are at least equal the modern $ 600-800 plus lenses.
Also, I love manual focus and the feel of quality built lenses, at the same time I will be able to use them on my film body and maybe one day on full frame digital

Thanks again to everyone.

Last edited by Gregs; 08-22-2009 at 09:37 PM.
08-22-2009, 09:34 PM   #10
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QuoteOriginally posted by newarts Quote
Yes. A circular gasket of cardboard or wire will probably make the flange thick enough.

Use a file to "square off" the fillets on the bayonet ears of the adapter; the photo shows a Pentax adapter on the left & a clone on the right. This helps prevent over-rotation. Or drill an indent in the lens' base to lock the lens into position.


Dave
Thanks a lot Dave I will try this , you just gave me some good ideas, perhaps I will drill a little hole - indent, after all.
08-22-2009, 09:47 PM   #11
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QuoteOriginally posted by Steve Beswick Quote

By the way, you can buy the "real" adapter straight from Pentax for roughly $30.
What???? Where??? I was told you can't get a genuine one anymore.
I asked Pentax Australia and they haven't got any. Can you please give me some link to a place where I can buy them?
08-22-2009, 10:16 PM   #12
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QuoteOriginally posted by Peter Zack Quote
I agree with xjjohnno, just use the original.

You'd have to drill a locking pin slot in the back of each lens for it to lock in place. Otherwise you risk turning the lens right off the camera when adjusting aperture or focusing. You could easily drop the lens.



... and you can replace lenses quite quickly with M42's
I don't get it either.

Can it really be that challenging to screw a lens or a bunch of different lenses on and off?

Just leave the Original proper adapter on the body while shooting M42.

I really fail to see how it's more likely to get dust in the camera this way, more so than using regular K-mount lenses too, btw.

Oh, and not only can you damage a lens with a ring that won't lock when the lens falls off. Wasn't there somebody in here that broke his/her camera when an M42 lens fell off causing the camera and tripod to fall over?

Regards,
Mike
08-22-2009, 10:23 PM   #13
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Bought mine from Henry's in Canada for reasonable shipping price. Some Oz member said he'd managed to order one through CR Kennedy so an email to them might be in order to see what they can source you one for.
08-23-2009, 12:53 AM   #14
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QuoteOriginally posted by X Man Quote
I don't get it either.

Can it really be that challenging to screw a lens or a bunch of different lenses on and off?

Just leave the Original proper adapter on the body while shooting M42.

I really fail to see how it's more likely to get dust in the camera this way, more so than using regular K-mount lenses too, btw.



Sorry Mike I forgot to mention (silly me) that all this exercise to convert M42 to K-mount is to make it easier for myself when I juggle 14 lenses between M42 & K-mount on K20D,
as well as (sometimes) on ME super and PZ1p.
I’m not a professional photographer by any means, though it is my lifelong hobby and I’m very passionate about it.

regards
Greg
08-23-2009, 01:02 AM   #15
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QuoteOriginally posted by xjjohnno Quote
Bought mine from Henry's in Canada for reasonable shipping price. Some Oz member said he'd managed to order one through CR Kennedy so an email to them might be in order to see what they can source you one for.
Thanks for telling me , I will ring tomorrow morning CR Kennedys and hopefully they will be able to get me one, but it will have to be for not much more than el-cheapo from e-Bay

cheers
Greg
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