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Old Apr 16, 2011, 1:05 AM   #1
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Default Contax Carl Zeiss Lens on a Pentax body

All of this started out quite a while ago. I was looking for something smaller than the 12-24 for traveling and read a post and reply on another site that talked about a Zeiss lens. At $1,200+ that was not happening in my lifetime. So fast forward to last Thanksgiving and I was looking on Craigslist and saw a Contax Carl Zeiss 28mm f2.8 T* Distagon lens for $250. The seller was slightly mistakened in his description that it worked on Pentax bodies. Not cheap, but a lot less than $1,200+, so I started quickly reading all about Contax lenses.

Contax was a very high end professional 35mm film camera where production stopped in 2005. Zeiss made their lenses, extremely high quality, all metal and glass, equivalent to Pentax's FA Limited glass. There was a full line of lenses, and they used the MM or C/Y mount - and there was NO adapter for Pentax. However, there was a company over in Spain that had a K mount conversion, with illustrated instructions.
The lens was not cheap, but I figured that I could afford to try it - once, so I took a flyer. I bought the lens, then ordered the conversion mount. That was at Thanksgiving - waited 11 weeks (through the holidays) for the US Customs (think Indiana Jones and the Arc in the Warehouse) and I had the parts on my doorstep. Had the conversion done, rather than me butchering the lens - not really knowing the internals. So, now I have it...

Its an all manual lens (manual aperture and manual focus) just like a K or M Pentax lens. Mounts just like a K or M lens now, and operates in Aperture Priority or Manual mode (need to enable the aperture ring setting in the menus) and you need to enter the focal length at startup. The camera body detects when its in focus with the focus point indication and the green hex indicator in the viewfinder. Stabilization works just fine. Infinity focus is perfect.

I have been taking images over the last several weeks, in the very late afternoons, dusk, early evening. Shooting the lens against my FA 31 limited. The Contax is sharper in the center, same or better IQ as the Pentax, depending on your eyes and what you are looking for. Pentax is better in the corners by a bit. Great contrast and rendering, with the Zeiss colors. It tends to underexpose a bit, with the shutter speeds being faster than what the FA 31 shoots at.

The build is great. The glass is great. Its a wonderful little lens. My total out of pocket is less than $400. A new Zeiss ZK 28/2 lens (which is also manual only) is $1200+ as is a new FA 31 Limited. So, for a 1/3 of the price, I have a Zeiss lens. Its at least 10 years old in absolutely mint condition, and shoots like a million dollars.

Overall its as good as the 31 Ltd - but different. Both are great lenses, and I do have to say, I feel very fortunate in being able to acquire them. They are both a lot of fun to shoot with. Now, all I have to do is to practice to increase my skill so that I will not embarrass myself shooting them.
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If your interested, here is what I have learned.

Here is a review of the lens....
Some additional useful links....You are able to determine the mount type by the color of the f22 aperture setting (green indicates that it’s a MM mount suitable for conversion - white indicates an AE mount that is NOT able to be converted). Also the MM mount can be identified as MMJ or MMG indicating where the lens was made (J = Japan, G = Germany).

The lens is fully multi coated using Zeiss’ T* coatings, one of the best available – however since the lens is at a minimum nearly 10 years, the coatings are not optimized for digital, however flare is virtually non existent. From what I have read the T* coatings were introduced in 1972, as it was Zeiss' multicoating process. In 1974 Zeiss started marketing "T*" in response to Pentax's SMC (Super Multi Coated) lens advertising.

Stick to only the lenses listed on the Leitax website, so as to eliminate any problems.

The conversion is fully reverseable and does not damage the lens, so keep the parts - just in case.
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Erick Hendrickson converted the lens for me. I heard of him over at the Pentax Forums. He has a long history of Pentax camera / lens repair starting back with Honeywell/Pentax. He is somewhat of a living legend over there repairing the manual camera bodies and lenses for folks. He did an absolutely wonderful job on the lens.

http://pentaxs.com/
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Last edited by interested_observer; May 4, 2011 at 5:58 AM.
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Old Apr 16, 2011, 8:12 AM   #2
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Sounds like a lot fun for very reasonable cost. I would love to see some sunsets from Tumbleweed using your new setup.
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Old Apr 16, 2011, 1:29 PM   #3
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An interesting conversion ... I can confirm the excellence of the Zeiss glass, I have a Zeiss Flektogon M42 35/2.8, I've fitted a M42/K adaptor semipermanently using a weak thread locking compound, and drilled the backplate to accomodate the cameras lens locking pin. I also removed the M42 auto stopdown parts, as they serve no useful purpose. Use is of course fully manual.
You may find it useful to add a foil washer to the mount to the lens mount to short all body contacts, this allows "Focus Trap" or as some term it "catch in Focus" operation. ... Jack.

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Old Apr 16, 2011, 11:11 PM   #4
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This has been a learning experience - believe it or not....

I have taken all of the images on a tripod, 2 second mirror up, external shutter release, ISO 100, AP mode on each lens, multi-segment metering at f4, same K20 body, really no changes - other than swapping lenses. The other thing is that I have been shooting 5 image brackets at 0, -.5, +.5, -1, +1 ev, and the shutter times are really staggering between the two lenses, with about a minute between sets (just swapping the lens).
lens....0ev....-.5ev..+.5ev..-1ev..+1ev
CZ 28 1/15...1/20...1/10...1/30...1/8 sec
PK 31 1/8.....1/10...1/6.....1/15...1/4 sec
One of the earliest sets, I tried the CZ against the DA 12-24 @24, FA 31, DA 16-45 @ 28. Interesting comparison. I knew that the 16-45 had a focus gear problem - I need to get it fixed, but I though I still should be able to use it in manual focus. It looks like I can't get all the way to infinity with it, so to the vets it goes.

In shooting with the CZ I have been trying to figure out the ev level to bias it with (since it underexposes), by shooting brackets with various ev intervals of .5, 1, 1.5, and 2. That is what I was doing this evening, however, I just found that the 31 catches the brilliant iridescent blue of the sky very easily, while you really have to work to get close to it with the CZ. Not everything is sharpness - its the pixie dust the 31 has apparently. That is the difference in character between the two lenses, and how they render various colors - I am finding blues are the hardest with this lens. At least for me.

Anyway - here is a shot from this evening with the CZ 28....

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Last edited by interested_observer; May 9, 2011 at 9:57 AM.
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Old Apr 17, 2011, 12:27 AM   #5
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Hi IO,

This is very cool! There aren't any applications where this would help me, but there seems to be a very comprehensive list of premium primes that someone with the means, patience, and persistence could collect and use.

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Old Apr 17, 2011, 12:29 PM   #6
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Very nice shot! Thanks for all of the detail, it's very interesting to understand the process as you work through it.
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Old Apr 17, 2011, 3:37 PM   #7
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I will say that each time I go out shooting, then come back and actually see what I have on a large monitor, I ask myself, why I did not try this or that. And that leads me to the next outing.

There is this little valley about a 5 minute drive from the house, that offers a western sunset view, a somewhat interesting valley vista with evening lights. So, I use this as somewhat of a lab to experiment with. There is a much more majestic view up in Sedona, but its a 2 hour drive one way.

As a comparison (to the last image posted), here is an image from the 31. Essentially this frame adjoins the CZ image just to the left (in fact the same house is in the lower right hand corner of the CZ image and lower left hand corner of the 31 image). It was a bout a week earlier, different sky, and the lens handles the ambient light much differently.

So the main differences I see are coloring and contrast within the rendering. I do like the way the CZ handles the shadows. I do not believe that the difference between these two lenses is just biasing the ev to adjust for the CZ's under exposure. There is much more.

I thought that I would just throw this in also. Its a set of posts from 2009 from the same area -

http://forums.steves-digicams.com/pe...-panorama.html

Anyway, I just feel lucky to be able to experiment with both of these.
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Last edited by interested_observer; Apr 17, 2011 at 3:47 PM.
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Old Apr 17, 2011, 8:52 PM   #8
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An interesting exercise, it's interesting to read what you have found about the characteristics between the two lenses. We over-estimated our tax last year so when B&H emailed that they were accepting pre-orders for the FA 31 (they've been out of stock for a while), I pushed the button. I have no idea when their stock will come in (they don't tell you that), but hopefully it won't be too long a wait.
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Old Apr 18, 2011, 2:07 AM   #9
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Went out again this evening to shoot the little town of Tumbleweed. I just shot the CZ 28. I did capture the sky that I wanted. I stitched 7 sets of 5 bracketed shots (actually only 4 of the 5 - as I left out the +1.5 ev since it turned early evening - 7.30pm, in to late afternoon ~5pm). I am still getting more noise from my K20 that what I would like or expect at ISO 100, but ...

Harriett - you will really like the 31, especially with your K5. The combination will be absolutely unbeatable. Right now its between my 12-24 and the 31 - with the 31 winning most of the time. I really do like a lot of things about the CZ, but I am starting to think that the Pentax sensor and body is set up (optimized) for the Pentax lenses - they are really easy to shoot with. Its not that the CZ is harder or more difficult, there is a lot to like about it, but I am just so use to knowing what I am going to get with the 31 and getting it, that I have to figure out this new lens. I do like it (the CZ) much better than the A50/f1.7. The CZ is brighter than the A50, I am finding.

Still the same setup - f4, bracketed...raw, straight out of the camera, no adjustments, and stitched with MS ICE.

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Old May 4, 2011, 12:48 PM   #10
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Interesting experience. I have a rather old CZ lens on my rather old Zeiss-Ikon Super Ikonta B medium format.

I have sometimes thought of getting a CZ lens...particularly the 100 Makro, which I believe comes with a PK mount.

But it is expensive....in fact uber expensive.

Sounds like you got a great deal and through resourcefulness made it work.

I envy you. I think you will derive many years of satisfaction using your CZ lens.
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