Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-08-2017, 04:49 AM   #1
Site Supporter
Site Supporter
cyberjunkie's Avatar

Join Date: Mar 2010
Location: Bologna, Amsterdam, Chiang Mai
Posts: 443
Any M42 lens hitting the mirror of the K-1?

Unlike some Canon FF cameras, the K-1 seems to be quite impervious to the mirror clearance problem caused by some (mostly M42) lenses with protruding back element/mounting ring.
At least i haven't found any reference to such problem on this forum.
If the problem exists, it would be nice to have a database of the optics involved.

Some lenses have either a very convex back element, or a very thick retaining ring.
For example in this version of the CZJ Flektogon 2,8/35mm the back ring could be shaved more than 1mm without affecting future cleaning/repairing projects:



Before mounting it on the K-1 i would like to be sure that it won't hit the mirror...

I am aware that not all M42/PK lenses are compatible without modifications.
There is the famous/infamous Ricoh pin... but there are other incompatibilities.
For example some Kiron/Vivitar/Panagor PK lenses have the diaphragm lever "guard" that protrudes too much. No problems with film cameras, but with Pentax DSLR's the "guard ring" touches the camera, and the lens can't be fitted.
Insisting might even procure some damage. The ring must be either removed or shaved.
I did the first two the elegant way, with a lathe, then i did it with a file, the brute way
Late Mamiya/Sekor M42 lenses have a recessed flange, with a pin and an elliptic indent. The diaphragm ring touches the camera before the lens is screwed in completely, to the correct register distance.
That way no infinity focus is possible. I'd like to know if somebody modified a Mamiya M42 lens with aperture simulator with some success.
EBC Fujinon lenses are much easier, the "tooth" can be either sawed or filed without dismantling the lens (pay attention to keep metal particles out of the lens).
Nothing else comes to my mind. I'd be grateful to learn about other incompatibility issues.
Thanks.

Cheers

Paolo

01-08-2017, 06:36 AM   #2
Loyal Site Supporter
Loyal Site Supporter




Join Date: Mar 2015
Photos: Gallery | Albums
Posts: 5,932
The best way to get around the Vivitar guard ring problem is either to buy a junk K-mount lens without the expanded flange and swap them, or simply remove the guard flange and be very careful with the lens. I used to think it was the SDM (former powerzoom) contacts that were the issue, but sure enough I tried to mount my late father in law's Vivitar 80-200/4.0 lens on my *istDS recently and it won't go. No loss, as I have an SMC-M 80-200/4.5 and numerous K mount film bodies I can shoot the Vivitar on.

The problem with filing the tab off an EBC Fujinon is that it wrecks it as thoroughly as cutting the aperture arm off a Takumar, K or M lens does. Sure you can still use it as a Super Tak even on Fujinon bodies, but that's not what their maker intended.
01-08-2017, 07:27 AM   #3
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 4,293
Some of the early Ultra-Wide Angle ("fisheye") lenses from the film era with long protruding rear elements were meant to be used in mirror lockup mode only. This was when bodies had a lever to lockup the mirror.

The K-1 mirror is designed to slide towards the sensor before and during the swing up towards the prism. In theory if the rear elements clear the mirror on film SLRs then it should clear on the K-1. In practice, who knows with non-Asahi/Pentax lenses?
01-08-2017, 08:01 AM   #4
UMC
Forum Member
UMC's Avatar

Join Date: Dec 2012
Location: Vienna
Photos: Gallery
Posts: 95
We had the same discussion in the German pentaxians.de forum some 3 weeks ago. Then it was discussed, whether or not a Soviet Mir 2.5/20mm lens with its rear element protuding by approx. 3.5 mm in infinite position would hit the mirror of a K-1. We came to a few conclusions:
  • If a lens was safe to work on the last analogue generation of Pentax cameras, it should be safe to operate on the K-1 either.
  • The 3.5 mm are not enough to hit the mirror.
  • The sliding mirror mechanism of the K-1 makes it even more safe compared to EOS cameras.
I personally do not remember any incompatibilities of K-mount lenses and cameras apart from the 2 above mentioned issues
  • Ricoh pin
  • Extended aperture lever guard
which both have a different technical background.


However, I would be careful with lenses manufactured earlier than let's say 1975....

01-08-2017, 08:38 AM   #5
Pentaxian
zzeitg's Avatar

Join Date: Sep 2014
Location: South Bohemia
Photos: Gallery | Albums
Posts: 2,641
I only had this problem once. It was K-7 and old Soviet MIR-I 2,8/37 mm combination. But I can't say if there's same issue in case of K-1.
01-08-2017, 01:12 PM   #6
Loyal Site Supportaxian
Loyal Site Supporter
jbondo's Avatar

Join Date: Sep 2013
Location: Texas
Photos: Albums
Posts: 422
I have quite a number of lenses that cause a mirror collision on my Canon 6D. All of those lenses work fine without interference on the K-1.
01-08-2017, 01:39 PM   #7
Site Supporter
Site Supporter
Fenwoodian's Avatar

Join Date: Apr 2015
Photos: Gallery | Albums
Posts: 1,303
I have tested over 20 M42 lenses with a variety of adapters on my K1. Never once did I have the mirror hit the back of the lens.

Based on my experience it's not an issue at all. The widest lens was 28mm, the longest 200mm.
01-08-2017, 08:49 PM   #8
Site Supporter
Site Supporter




Join Date: May 2016
Posts: 702
QuoteOriginally posted by cyberjunkie Quote
Before mounting it on the K-1 i would like to be sure that it won't hit the mirror...
If it's an M42 lens you already own, you could try inserting it into the lens mount hole without the K-mount adapter on it; that seems like it might be a safe way to check the clearance.

01-08-2017, 09:36 PM   #9
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 5,005
One that comes to mind is the Yashinon-DX 50/1.7 (and maybe the 1.4?) -- that will hit the mirror at infinity, even on an APS-C.
01-09-2017, 01:37 AM   #10
Site Supporter
Site Supporter
cyberjunkie's Avatar

Join Date: Mar 2010
Location: Bologna, Amsterdam, Chiang Mai
Posts: 443
Original Poster
QuoteOriginally posted by zzeitg Quote
I only had this problem once. It was K-7 and old Soviet MIR-I 2,8/37 mm combination. But I can't say if there's same issue in case of K-1.
That would be an interesting information!
I bought the MIR-1 short time ago, and i will find it when i go back home.
It is a peculiar lens, in both shape and rendition (flares and has a vintage optical signature, as far as i know).
The back of the lens touches just the adapter, not the camera body, so it should always be a bit wobbly, not firmly attached to the camera.
Before using it at infinity with my K-1 i'd be glad to know if the back of the lens clears the mirror!
Any first hand information?

cheers

Paolo
01-09-2017, 08:37 PM   #11
Pentaxian
Topsy's Avatar

Join Date: Feb 2014
Photos: Gallery | Albums
Posts: 501
My MIR-1 does clear it just fine.
If I remember right I measured everything last summer and came to the conclusion that there's still a gap of around 1mm to the mirror at infinity, maybe a bit less. But it clears it alright

See my post below

Last edited by Topsy; 4 Days Ago at 05:04 PM.
01-16-2017, 10:30 AM   #12
Site Supporter
Site Supporter
cyberjunkie's Avatar

Join Date: Mar 2010
Location: Bologna, Amsterdam, Chiang Mai
Posts: 443
Original Poster
Thanks Topsy,
good to know it

cheers

P
4 Days Ago   #13
Pentaxian
Topsy's Avatar

Join Date: Feb 2014
Photos: Gallery | Albums
Posts: 501
QuoteOriginally posted by Topsy Quote
My MIR-1 does clear it just fine.
If I remember right I measured everything last summer and came to the conclusion that there's still a gap of around 1mm to the mirror at infinity, maybe a bit less. But it clears it alright
QuoteOriginally posted by cyberjunkie Quote
Thanks Topsy,
good to know it

cheers

P
I need to redact that comment.
I just tried it on another adapter and, assuming that it can't be the adapter, I must've not checked well enough.

The mirror does hit the mirror ever so slightly at infinity, but you can't really hear much of a difference, but if you pay very close attention you'll notice that the camera vibrates slightly more with the lens at infinity.
I'll need to check if I can modify the back of the lens and how much it'd need.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, cameras, diaphragm, dslr, full frame, full-frame, k-1, k1, lens, lenses, m42, pentax k-1
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Any reports of mirror flap on the K3 II? Fat Albert Pentax K-3 30 10-02-2017 03:07 PM
The Exposure section of the IR K-1 review is out for the K-1. normhead Pentax K-1 9 07-03-2016 10:05 AM
Any advantage of a Pentax vs Sigma UWA lens with the K-50's distortion correction? bladerunner6 Pentax SLR Lens Discussion 4 06-13-2016 03:55 AM
Is the K-1 getting the best reception of any camera ever on this forum? jake14mw Pentax K-1 34 05-12-2016 04:20 PM
Lens hitting the mirror? K5 IIs Tighelander Troubleshooting and Beginner Help 8 10-07-2013 12:02 AM



All times are GMT -7. The time now is 03:42 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top