[limr]

I've got a Honeywell Pentax SP 500 Spotmatic. It's got the M42 screw mount, not the K-mount. I just bought a Carl Zeiss Jena Tessar f2.8 50mm lens that arrived in the mail today. Super excited. I put it on the Spotmatic and everything seemed fine. Loaded some film and the shutter would not fire with the lens screwed on. As I slowly unscrewed the lens, I'd then hear the mirror slap.

I put the camera in B mode to isolate the opening/closing to see what was going on. The shutter is firing, but it looks like the lens back is too far into the camera and preventing the mirror from flipping up. The final test was to put the lens on very slowly and test the shutter at different points. With the lens screwed in up to halfway or so, maybe a bit more, the mirror seems to have plenty of room, but with it screwed in all the way, the mirror can't flip up.

Is this a common problem with this lens and camera combo? Or is this an oddball? Is there a fix for it? I'm very excited about this lens and I'm not ready to believe I won't be able to use it!

[limr]

Nothing? Was this the wrong place to post this thread?

[Swift1]

Can you post a photo of the lens?
The M42 mount was fairly widely used and different manufacturers had very slight variations of it.
I'm guessing the lens was likely made for the Praktica cameras or maybe the Contax D. Those cameras likely have smaller mirrors.
Can you focus past infinity?

[limr]

Thanks for the response! I can post a picture of it in a couple of hours when I get home. I only had the lens on briefly and it seemed to be able to focus past infinity, but I'll check that for sure before I say yea or nay.

[limr]

This isn't mine, but I found this picture and it's exactly like the one I just got:
CZJ_Tessar_2.8/50_T_(`54)_04 | Flickr - Photo Sharing!

Mind doesn't have the k-mount adapter but everything else is the same.

Maybe it will work on my K1000 with an adapter, then?

Edited: Forgot to add that I found that picture from a review on this forum:
https://www.pentaxforums.com/userreviews/carl-zeiss-jena-50mm-f2-8-tessar.html

[Swift1]

The black bit on the end of that lens protrudes a fair amount farther than all the Pentax Takumar lenses.
I guessing the example in the review worked on a DSLR because they have smaller mirrors.

[limr]

I didn't know that about DSLRs. At some point when I get one, then I might try this lens on it. But the reviewer was using it with a Spotmatic. It was definitely a later one than the one I have since he was using the K-mount adapter and mine still has the screw mount. I'm going to look into getting an adapter to see if I can use the Tessar on my K1000.

Thanks for your help!

[stevebrot]

The black bit on the end of that lens protrudes a fair amount farther than all the Pentax Takumar lenses.
I guessing the example in the review worked on a DSLR because they have smaller mirrors.

Mirror clearance was a big deal back-in-the-day. Lenses that should have worked with multiple brands of bodies often didn't.


Steve

[stevebrot]

I didn't know that about DSLRs. At some point when I get one, then I might try this lens on it. But the reviewer was using it with a Spotmatic. It was definitely a later one than the one I have since he was using the K-mount adapter and mine still has the screw mount. I'm going to look into getting an adapter to see if I can use the Tessar on my K1000.

Thanks for your help!

The reviewer may have been using A CZJ Tessar 50/2.8 on a Spotmatic, but it may be good to note that it may have been a different version of the Tessar 50/2.8. The Tessar 50/2.8 has been made in several different styles with the last being fairly recent. Your lens (if the same as the linked photo) has a pre-set aperture and is early. Later versions have auto-aperture and a different rear design.


Steve

[titrisol]

There are a few versions of this lens, I used to have one (latest model I think) which worked fine in the Spotmatic and the fujica St-801.
However on an older version maybe the pin or the back of the lens are touching the mirror?

[titrisol]

Don;t get antsy, peopl ehere usually take a few hours to answer your queries, even days....

Nothing? Was this the wrong place to post this thread?

[limr]

There are a few versions of this lens, I used to have one (latest model I think) which worked fine in the Spotmatic and the fujica St-801.
However on an older version maybe the pin or the back of the lens are touching the mirror?

There's no pin. It's a very old version of the lens and it looks exactly like the one in the link I posted above. (CZJ_Tessar_2.8/50_T_(`54)_04 | Flickr - Photo Sharing!) The only difference is that his says "Carl Zeiss Jena" and mine says "C.Z. Jena".

Did some more testing - it starts hitting the mirror on the upswing a quarter turn from fully screwed, and on the way down, almost a full turn away from fully screwed. I am going to get a K-mount adapter and see how it works on the K1000 instead.

Don;t get antsy, peopl ehere usually take a few hours to answer your queries, even days....

Didn't mean to sound naggy, but it had been a few hours since I'd posted. I was worried that I posted in the wrong section.

[stevebrot]

However on an older version maybe the pin or the back of the lens are touching the mirror?

The version he says he has has no pin (preset lens), but does have a substantial "collar" at the rear of the mount that is catching on the mirror.


Steve

[stevebrot]

and see how it works on the K1000 instead.

I am not hopeful that you will have better luck with the K1000. Compare the mirror length for both cameras and I think you will find that they are the same.


Steve

[stevebrot]

Didn't mean to sound naggy, but it had been a few hours since I'd posted. I was worried that I posted in the wrong section.

You are definitely in the right section, but four hours is not a very long time for the film SLR section. 24 hours and you might have a reason to complain. However, I have consulted with the technical staff and in the interest of good customer relations, we have agreed to give you a full refund for our free advice


Steve