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08-12-2009, 10:00 AM   #1
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Found a good M42 - K mount adapter

Maybe some of you already know that adapter but I but 2 different ones and that one is a lot better and pretty cheap too (around $8). The nice thing about it is that it locks on the camera mount like a normal lens and can be unlock the normal way.

If some of you are interested I can send them the link from eBay, but I'm sure you can find it too if you search link me for a M42 Lens Adapter M42 Screw Mount to Pentax PK.





Last edited by YJD; 08-12-2009 at 10:52 AM.
08-12-2009, 10:08 AM   #2
Igilligan
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WAIT!!!

I have one of those... the issue with that type of flanged adaptor is that because of the thickness of the flange you loose infinity focus on the lenses.

It is perfect for a M42 bellows though, and for macro lenses where you may not need infinity...

Do not get these if you need to focus thru the entire range of the lens
08-12-2009, 10:13 AM   #3
YJD
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Well, I have seen any problem with my Takumar 135/3.5. I could do some more test tonight and maybe the lens I have don't have that problem.

Anyway, the focus in manual so I should be able to focus to infinity, no?
08-12-2009, 10:21 AM   #4
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No, not exactly... for lenses to focus to infinity they need to sit flush against the camera / lens mount. The extra thickness of that adaptor sitting above the mount will throw the distance between sensor and lens off a bit.

08-12-2009, 10:29 AM   #5
YJD
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OK, I get it now. I'll have to make some test to see how bad it is but I though that for $8 shipping include (from China). It was a pretty good deal compare to the other cheap mount that I bought and it wouldn't lock to the camera (it looked like the official Pentax one except way cheaper as I already mention).

Though, would the Pentax one create that extra thickness to it?
08-12-2009, 10:39 AM   #6
Igilligan
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No the pentax adaptor sits flush with the body/lens mount. It lets the lens sit flush against the mount.

I just did a test with the helios and vivitar 135 and they are both off at infinity... (the fence in the backyard is blurry, and can not be focused.

With the 58mm helios I have about 18ft of usable focus range. Anything past that is blurry.

It would be great if you could get the mods to let you change the title of the thread as it might confuse some with the "best" in the title.

It is usable, but not the best for all situations. Unfortunately, IMHO the best is still the pricey original Pentax version.

I am one of the cheapest guys with a camera... I cant wrap my mind around 700 dollars for a DA 55 when I have a 20 dollar Helios. But when it comes to this adaptor... there is no question the original is worth the extra money...

PentaxWebstore Mount Adapter B (35mm Screwmount to Bayonet)

Last edited by Igilligan; 08-12-2009 at 10:44 AM.
08-12-2009, 10:54 AM   #7
YJD
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I change the title to good instead of best and I will do the test.
What you are saying is even though you are focusing to infinity, the focus isn't showing when taking a picture.
Thanks for all the info and I'll give it a try tonight.
08-12-2009, 11:18 AM   #8
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if this adapter had an inner flange for depressing the auto pin, and I could swap the locking clip from my genuine pentax onto this, it would be just about the perfect adapter. to bad its expensive as all get out, and not sold really anywhere that I know of outside Japan. cool looking though.

近代インターナショナル製品情報(M42レンズ用マウントアダプター)

08-12-2009, 11:35 AM   #9
Igilligan
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Ok I see why you did not notice the infinity issue...

I just did the focus test with my Vivitar 135 2.8 and the focus range is approx...
3ft to 100ft... anything past 100ft goes blurry.

And with my 28mm and the range is 1ft to 3ft

So it would have been difficult to see an issue, unless you were focusing past 100ft.

So from my quick little tests with my lenses / flanged adaptor

A 28mm has a max focus distance of about 3ft (anything past 3ft goes blurry)

A 58mm has a max focus distance of about 18ft

A 135mm has a max focus distance of about 100ft
08-12-2009, 11:40 AM   #10
YJD
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That's a pretty good test, I don't think I'll be able to get something that technical but I'll try something anyway.
08-12-2009, 12:25 PM   #11
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With regard to the shift of infinity focus see this thread:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/68480-infinity...tml#post689140
08-12-2009, 05:34 PM   #12
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Well, as you said, with some hope you all were wrong, it doesn't focus to infinity... I'm going to keep this adapter and next time I'll buy the official Pentax one, especially if I buy another M42 lens!

Thanks for the warning Gus and thanks to everyone with links and tips. I don't want to do modification to the lens, though I may try sanding the adapter later on but what is the point? If I sand to fix the infinity problem, it won't hold my lens in place!

Is the official Pentax adapter is really well build? I'm asking that because the first one I bought looked exactly like the Pentax but that little piece of metal got undone the version time I pull the adapter off the camera.
08-12-2009, 07:45 PM   #13
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I only use the Pentax M42 adapter and have never had any issues with focusing.
08-12-2009, 08:56 PM   #14
Igilligan
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I have never had an issue with the clip on the Pentax adaptor. The advantage to the pentax adaptor over the cheapies that look like it, is that the original only needs your finger nail to unlock the clip and spin the adaptor off. It does not need that tool...


As I said those flanged adaptors have their uses. Macro shooting seldom needs infinity focusing and they are perfect for use with a M42 macro bellow unit.
08-12-2009, 09:00 PM   #15
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It may be possible to adjust the lens' infinity focus to accomodate the extra thickness of the flange. This involves some lens disassembly; it is not a dangerous or particularly difficult thing to do. There may be enough adjustment available & there may not be.

There was a recent thread on how to do it. https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/54595-flanged-...xperiment.html

Dave
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