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08-05-2008, 05:40 AM   #1
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Zeiss Sonnar T*: Do the mod to Pentax? Or sell it?

Greetings all,
I'm an old school film shooter who just got my first DSLR (a Pentax K200D). Using manual focus lenses on it was one of the big appeals to my choosing it.

Coincidentally, a few months earlier, I happened upon a Carl Zeiss Sonnar T* 85mm f/2.8 Y/C in mint condition for $5. (local store with photo dept. was closing out all their used lenses). When I saw the Zeiss name, I knew I had to have it, even though I knew nothing about it and have no Contax/Yashica mount cameras! I was delighted to learn it brings around $250 on eBay.

But now I find this:
How to convert Yashica/Contax to M42 mount Photo Gallery by Wesley Wong at pbase.com so I have the possibility of using it on my K200D (with a M42 to K-mount adapter). Both Pentax and Contax had the same 45.5 lens to focal plane distance. The lens is widely regarded as superb.
Carl Zeiss Sonnar T* 85mm f/2.8 (C/Y) Lens Review - Digital SLR Lens and Camera Reviews and gives me an equivalent 127mm focal length, which is perfect for portraits.

Examples of images shot with the lens (and other Zeiss lenses) are freaking me out with their sharpness. The images almost appear 3D. I can't find a LOT of examples of images taken with it, but the ones I can find all appear to positively leap off the page, they are so sharp (like this one):

Agfa Karat IV on Flickr - Photo Sharing!

And this one: C/Y Zeiss 85/2.8 Sonnar Question - FM Forums

These aren't 85mm examples, but still the sharpness almost cuts you:
Manual Focus Lenses :: View topic - Contax lens questions

I found a comment on Flickr that it was one Canon shooters favorite lens (used with an EOS adapter).

Now I'm thinking maybe I'd be crazy to SELL it and am considering doing the mod. What do you think? Comments in addition to votes will be VERY welcome.

Darren Addy
Kearney, Nebraska USA

08-05-2008, 09:19 AM   #2
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First of all, congratulations on getting a $250 lens for $5! That's an incredible deal.

Here is what I would do. I would buy the adapters and see if you like using the lens on your K200. If you don't, you could sell both the lens and the adapters. Adapters don't cost much, so it should be a cheap experiment. I just bought an M42 to K-mount adapter on adorama.com for $15 new. I don't know what the Yashica to M42 adapter would cost but, again, adapters aren't often more than $35 unless you want one that preserves the auto functions, and Zeiss stuff is usually manual everything anyway, so that won't be a concern. Even if you ended up having to eat the cost of the adapters, you still would make almost $200. If you are an old film guy, you probably ought to have an M42 to K-mount adapter anyway.

My only concern with two adapters mounted to each other is that you might lose some ability to focus near infinity. You would want to check that out once it is on your camera. Not a concern for portraits, obviously.

Good luck.
08-05-2008, 09:25 AM   #3
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fixing the focusing distance could be solved with a little bit of dirty work.

most old lenses focus using a barrel screw mechanism. You have the outer shell, and you have the internal tube with all of the glass elements in it.

it moves back and forward thanks to a very simple threaded mechanism and a couple of vertical pins... its hard to explain, much easier to udnerstand once you take it apart.

if focusing to infinity is a problem, all that has to be done is a re-alignment of the inside tubes, for this you just need to take it all apart, take out the tube, then put it back at a different start point.

viola
08-05-2008, 12:48 PM   #4
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Well there ARE no Y/C to screwmount or K adapters because Y/C and Pentax have an identical 45.5mm lens to focal plane distance. Any adapter is going to move the lens farther away from the lens and you'll have the infinity problem you guys are talking about.

However REPLACING the Y/C mount on the Zeiss with a screwmount harvested from an old lens will then allow you to screw it into a K-mount M42 adapter with identical 45.5mm lens to focal plane distance. That's what this guy is showing how to do:
How to convert Yashica/Contax to M42 mount Photo Gallery by Wesley Wong at pbase.com

I don't think the mod looks that scary, but then I'm better at taking things apart than at putting them back together.

It seems to me that you are doing nothing destructive to the Zeiss, just the harvested mount... so nothing seems to be keeping one from going back to the Zeiss mount again.

OK. This clinches it. I'm doing the mod. I gotta see what this does on my K200D.

Darren Addy
Kearney, NE


Last edited by cheekygeek; 08-05-2008 at 01:00 PM.
08-05-2008, 01:13 PM   #5
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QuoteOriginally posted by Gooshin Quote
...most old lenses focus using a barrel screw mechanism. You have the outer shell, and you have the internal tube with all of the glass elements in it.
...if focusing to infinity is a problem, all that has to be done is a re-alignment of the inside tubes, for this you just need to take it all apart, take out the tube, then put it back at a different start point.
This sounds exactly like what I need to do to convert an LTM (L39) Industar-26 to a M42 mount. What tools did you use?
08-05-2008, 02:58 PM   #6
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I seem to recall being able to slap a K-mount on there as well. Get one of those old cheapy TC's for a few bucks and just remove the mount from there. There was a place out there where someone showed how, but I don't have the link on this computer.
08-05-2008, 03:23 PM   #7
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Heheh, I just remembered I discussed it here. https://www.pentaxforums.com/forums/pentax-camera-accessories/16428-contax-ya...s-adapter.html
01-21-2009, 04:21 PM   #8
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cheekygeek,

did you get it to work? I have been wanting to do the same thing for a long time now. please let me know.

also, I came across this on the interwebs Leica & Pentax | Leitax

Also, I understand that even if you could get the lenses to mount, there might be focal length and metering issues? have you overcome these at all?


Last edited by gozerthegozarian; 01-21-2009 at 04:43 PM. Reason: more questions
01-21-2009, 05:31 PM   #9
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QuoteOriginally posted by cheekygeek Quote
Well there ARE no Y/C to screwmount or K adapters because Y/C and Pentax have an identical 45.5mm lens to focal plane distance. Any adapter is going to move the lens farther away from the lens and you'll have the infinity problem you guys are talking about.

However REPLACING the Y/C mount on the Zeiss with a screwmount harvested from an old lens will then allow you to screw it into a K-mount M42 adapter with identical 45.5mm lens to focal plane distance. That's what this guy is showing how to do:
How to convert Yashica/Contax to M42 mount Photo Gallery by Wesley Wong at pbase.com

I don't think the mod looks that scary, but then I'm better at taking things apart than at putting them back together.

It seems to me that you are doing nothing destructive to the Zeiss, just the harvested mount... so nothing seems to be keeping one from going back to the Zeiss mount again.

OK. This clinches it. I'm doing the mod. I gotta see what this does on my K200D.

Darren Addy
Kearney, NE
but why go screw mount?

purchase a flanged M42 to K mount adaptor and just screw it to the lens base in place of the existing bayonet mount. Look at the thread for converting nimons to pentax. Same process.
01-22-2009, 09:08 AM   #10
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QuoteOriginally posted by RioRico Quote
This sounds exactly like what I need to do to convert an LTM (L39) Industar-26 to a M42 mount. What tools did you use?
I'm not sure about the Industar specifically, but Leica registration distance is a lot shorter than Pentax. Some lenses have the ability to adjust a mm or two, but I'm pretty sure any LTM is doomed to have a couple of feet max of focus range.

If you wanted to try, a mini screw driver set is all you should need (the kind you might use to fix glasses). I also have found that liquid dishsoap and a bit of warm water along with a discarded toothbrush is a gentle and effective way to clean and degrease everything. White lithium (VERY conservative amount) will bring your helical back to smooth sailing.

K.
01-22-2009, 05:03 PM   #11
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Ummm yeah...LTM is a no-go unless you want a macro lens/veryyyyy close portrait lens. I mean, uncomfortably close.

Pentax register distance is 45.46mm...Leica M39 is 28.8mm.
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