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07-22-2020, 12:33 PM   #1
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M42 lens hitting the mirror of the K-1

Hi everyone,

I noticed there is a thread asking about the question. But I didn't see many lenses are listed. I have tried 30 M42 lenses on my K1 and below are some that hit the mirror. Hope more lenses can be added so that it could help other K1 users.

Lenses hitting the mirror on K1:

Meyer-Optik-Goerlitz Primoplan 58mm f/1.9 (the version after WWII, 39.5mm filter, hit at infinity)
A. Schacht Ulm Edixa-Travegon 35 mm f/ 3.5 (the chrome version, hit at infinity)


Lensese hitting on mirron on K3:

Schneider kreuznach edixa tele xenon 135mm f4 (added by Cerebum)
yashika DX 55mm f1.7 (added by Cerebum)


Last edited by xinanbei; 07-27-2020 at 09:14 AM. Reason: Typo
07-22-2020, 12:39 PM   #2
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My Schneider kreuznach edixa tele xenon 135mm f4 use to hit the mirror of my K3 as did my yashika DX 55mm f1.7 Really annoying as they were both fabulous lenses
07-22-2020, 02:08 PM   #3
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Which adapter are you using? The Pentax one or third party?
07-22-2020, 03:02 PM - 1 Like   #4
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QuoteOriginally posted by xinanbei Quote
I noticed there is a thread asking about the question. But I didn't see many lenses are listed.
Do you have a link to the other thread?

Clearance issues with mirror or other aspects of the mirror box are not unusual, particularly with 1950s-era German lenses. Many caused problems even on M42 bodies of the day. A reasonable screen for new lenses is to place your M42 adapter on the lens and take note of whether any parts impinge more than close-fit lenses that you know to be safe. Don't forget to carefully consider the aperture actuator pin. If it is a little too long or too near the edge, it can foul the power contacts of a KAF2 body.


Steve

07-22-2020, 04:44 PM - 1 Like   #5
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Here's one thread I remember: Any M42 lens hitting the mirror of the K-1? - PentaxForums.com

That MIR of mine still never had the announced date with my lathe.
07-23-2020, 10:43 AM   #6
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How about mounting an offending lens on a short PK extension tube? You'll lose infinity focus, but may still be able to use the lens for some things.
07-23-2020, 12:44 PM   #7
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QuoteOriginally posted by Apet-Sure Quote
How about mounting an offending lens on a short PK extension tube? You'll lose infinity focus, but may still be able to use the lens for some things.
A flanged adapter might also be enough.


Steve
07-27-2020, 09:14 AM   #8
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QuoteOriginally posted by Cerebum Quote
My Schneider kreuznach edixa tele xenon 135mm f4 use to hit the mirror of my K3 as did my yashika DX 55mm f1.7 Really annoying as they were both fabulous lenses
Thanks for the info. Added.

---------- Post added 07-27-20 at 09:16 AM ----------

QuoteOriginally posted by bobbotron Quote
Which adapter are you using? The Pentax one or third party?
As long as the adapters ensure infinity focusing, the types should not be a matter, IMHO.

I used both the Pentax one and an high end third party adpater.

---------- Post added 07-27-20 at 09:17 AM ----------

QuoteOriginally posted by Apet-Sure Quote
How about mounting an offending lens on a short PK extension tube? You'll lose infinity focus, but may still be able to use the lens for some things.
Definitly help avoiding the hitting mirror problem. May not be a desired solution for every one...


Last edited by xinanbei; 07-27-2020 at 09:20 AM.
07-27-2020, 01:14 PM   #9
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QuoteOriginally posted by xinanbei Quote
As long as the adapters ensure infinity focusing, the types should not be a matter, IMHO.
"High end"adapters with a "shelf" intended to depress the aperture actuator pin are a common cause of mirror box incompatibility.

As for infinity focus, sometimes compromise is the only solution. I am expecting a flanged M42 adapter on Wednesday. This is a first for me, but needed due to a serious incompatibility between my K-3 and potentially any other Pentax dSLR I might mount my KMZ Helios 44M 58/2.0 to. I did a little estimation and determined that I should be good out to about 10-15 meters without modification, which would be fine for my usual subjects with that lens on APS-C.

As to the nature of the incompatibility, many Helios 44M lenses have aperture actuator pins that are a little longer than the usual and which are located further toward the edge near the threads than most. The combination may result in the pin striking the KAF2 power contacts on the last few rotations while mounting/removing the lens. This may be detected by a slight double click sound and/or actually feeling the strikes through the fingertips. If the adapter is already attached, this is heard/felt just before the adapter locks in place. Depending on the lens, the pin may come to rest against the contact. Over time, the power contacts may be physically scored such that good functionality may be compromised.

That last is the first I have mentioned it on the forums and I should probably follow up with a formal post with photos given the popularity of the lens.


Steve

Last edited by stevebrot; 07-27-2020 at 02:26 PM.
1 Day Ago   #10
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QuoteOriginally posted by stevebrot Quote
"High end"adapters with a "shelf" intended to depress the aperture actuator pin are a common cause of mirror box incompatibility.

As for infinity focus, sometimes compromise is the only solution. I am expecting a flanged M42 adapter on Wednesday. This is a first for me, but needed due to a serious incompatibility between my K-3 and potentially any other Pentax dSLR I might mount my KMZ Helios 44M 58/2.0 to. I did a little estimation and determined that I should be good out to about 10-15 meters without modification, which would be fine for my usual subjects with that lens on APS-C.

As to the nature of the incompatibility, many Helios 44M lenses have aperture actuator pins that are a little longer than the usual and which are located further toward the edge near the threads than most. The combination may result in the pin striking the KAF2 power contacts on the last few rotations while mounting/removing the lens. This may be detected by a slight double click sound and/or actually feeling the strikes through the fingertips. If the adapter is already attached, this is heard/felt just before the adapter locks in place. Depending on the lens, the pin may come to rest against the contact. Over time, the power contacts may be physically scored such that good functionality may be compromised.

That last is the first I have mentioned it on the forums and I should probably follow up with a formal post with photos given the popularity of the lens.


Steve
Hi Steve,

Thanks for pointing out the "shelf" may cause the incompatibility problem. That is something I am truely not aware of, and have not encountered yet. The two listed lenses in my first post have pre-set apertures, so the "shelf" was not used in those cases.

I also own a flanged adapter, but have not used it for years after I got the Pentax oringinal one and the "high end" (pricey) one. I agree with you that the hitting mirror problem will be less a concern with the extra distance to the mirror, It is surely a option based on the shooting subject.

Look forward to reading your post on the lens. Discussions help me a lot.

Ray
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