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Thread: Contax/Zeiss 135 2.8 conversion to a-mount

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    Contax/Zeiss 135 2.8 conversion to a-mount

    I purchased this lens already converted; one of the questions that I asked was whether it focused to infinity and with the assurance that it did I closed the deal. Turns out it doesn't.

    It focuses OK at about 150 yards when set to infinity. I have yet to take it apart and look for ways to bring the lens closer to the sensor. It came with one of the James Lao "4 lens" chips which I would like to replace with a single-lens chip. I'm wondering if anyone has info on thickness of various chipped bayonets, experience converting this particular lens, is there an adjustable stop for infinity, etc.

    Markings are as follows:

    Barrel: "Made in Japan"

    Front Ring: "Carl Zeiss Sonnar 2.8/135 T* 6869037"
    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    When you say it has a James Lao chip do you mean just the chip or a complete adapter? If it is just a chip what kind of adapter does it have.

    I found that using an m42 adapter milled out to fit over the top lip of the flange on a 35-70 f3.4 vario I had to file down that top lip somewhat to get the flange to fit flush to the lowest surface of the flange. You should probably first check to see if you can fit anything between the bottom of the converter and the top of the lens flange. If you can the converter is probably hanging on the top lip and filing down the top lip will quite likely give you infinity focus. It is tight but I was able to get it when I could fit the adapter flush. My adapter was also thinned on the flat surface where it attaches to the lens and had to be glued on. The thinning was done at an earlier stage so I'm not sure if it was necessary or not.

    If there isn't any space you may want to have the adapter itself thinned down but keep in mind that you may lose the ability to countersink the attachment screws and have to glue the flange to the lens with holes drilled through the adapter to allow taking the whole lens flange and adapter off for lens repair or maintenance?

    I have a 135 I was going to convert but I munged a couple of the flange screws and am unable to disassemble it without further work than I have done thus far. How do you like it for shots up to where it won't focus?

    Mike

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    I'm not sure of the origins, but AFAIK Lao is the only one offering the "4-lens" chip. I'll take it apart and look into it -- the screw heads are a bit buggered up though. I'll want to replace the screws. It does appear as if there is roo to bring the mount closer to the lens.

    I need to take some more shots with it to give a good assessment -- I took a few non-critical shots to get a sense of exposure variation at different apertures(normal with converted lenses, it seems) and a couple at infinity to verify that it could focus to infinity(it couldn't). This thing needs a lot of work, I should play with it a bit and make sure the IQ is worth it. The captures I have seem pretty sharp but I need to do some careful testing. The chip has to go IMHO, it's annoying and doesn't have the correct data for 135/2.8. This last issue is a nitpick, it only affects EXIF.
    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    The idea of a 4 lens chip is to select a different aperture and fl for different lenses but in the case of zeiss lenses it doesn't make sense because by the time you fit it taking it back off again won't be an attractive nor desirable option. Lao, can do a 1 lens with custom configuration though if 135mm f2.8 is important. The focal length is also supposed to help in the auto stabilization. Eventually I suspect other vendors will start selling programmable rom chips for the lenses just as they did for the canon focus confirm chips.

    Those zeiss screws are very difficult to find in my experience. If you find a good source please pass it on.

    Leitax also makes a conversion item. I've not seen one so don't know how well it works nor how much trouble it is to fit it.

    The photodo numbers look pretty good for this lens. I got it with the idea of using it for panos and mosaics. I'm getting a little more interested in bokeh though and don't how good it is in that respect.

    Quote Originally Posted by Dave_Anderson View Post
    I'm not sure of the origins, but AFAIK Lao is the only one offering the "4-lens" chip. I'll take it apart and look into it -- the screw heads are a bit buggered up though. I'll want to replace the screws. It does appear as if there is roo to bring the mount closer to the lens.

    I need to take some more shots with it to give a good assessment -- I took a few non-critical shots to get a sense of exposure variation at different apertures(normal with converted lenses, it seems) and a couple at infinity to verify that it could focus to infinity(it couldn't). This thing needs a lot of work, I should play with it a bit and make sure the IQ is worth it. The captures I have seem pretty sharp but I need to do some careful testing. The chip has to go IMHO, it's annoying and doesn't have the correct data for 135/2.8. This last issue is a nitpick, it only affects EXIF.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Yes, I understand the intent of the 4-lens chip, obviously it makes a lot more sense for M42 or T-mount. Having it report 135mm for SSS is more important than having it report the correct aperture, but in the process of ridding myself of the "4-lens" annoyance I might as well get one that reports the correct max aperture.

    As for the screws, I'm hoping I can just replace them per spec(dia/thread pitch/etc.) but I have to get them out first. Hopefully this week I can dig in. I also picked up information elsewhere that I can adjust the infinity focus without removing the mount, but it doesn't fit as well as I'd like and I want to tighten it up anyway. I'll update this thread with new info as I get it.
    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Doc, I managed to get outside in daylight and get a few more snaps with this lens. I'm going to work at it a bit more this weekend since I only shot wide-open, but here are my initial thoughts:

    • Very sharp within it's very narrow DOF.
    • Color fringing on highlights, e.g. magenta fringe on edge of leaf that is @ 98% saturation in all channels; edge is against dark background, center of frame
    • Color fringing goes away where highlights are less saturated.
    • Bokeh looks very nice.


    It looks like this lens can be a real gem if I expose with care. I'm going to play with it some more, down to f11 or so and then decide what to do. I may have a source for screws, a local repair shop that says they have a lot of loose screws(my wording, not theirs). Given that the original mount is long gone, I don't care much whether I can find exact matches for the originals -- just so long as they hold the mount securely.
    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Sounds promising. I was looking at opinions on the leica 135 f2.8 tonight and it apparently is not of the more favored lenses in the stable. I was checking because a leica conversion is a lot less trouble than a contax now that there are replacement flanges available on ebay. They don't have a focus confirm chip but they do have a place to glue on on.

    I also have an m42 125mm lanthar that I haven't tried yet as my camera is currently with sony for repair and awaiting back ordered parts.

    I'll be interested in seeing some shots when you get some you feel like showing.

    Best,

    Mike

    Quote Originally Posted by Dave_Anderson View Post
    Doc, I managed to get outside in daylight and get a few more snaps with this lens. I'm going to work at it a bit more this weekend since I only shot wide-open, but here are my initial thoughts:

    • Very sharp within it's very narrow DOF.
    • Color fringing on highlights, e.g. magenta fringe on edge of leaf that is @ 98% saturation in all channels; edge is against dark background, center of frame
    • Color fringing goes away where highlights are less saturated.
    • Bokeh looks very nice.


    It looks like this lens can be a real gem if I expose with care. I'm going to play with it some more, down to f11 or so and then decide what to do. I may have a source for screws, a local repair shop that says they have a lot of loose screws(my wording, not theirs). Given that the original mount is long gone, I don't care much whether I can find exact matches for the originals -- just so long as they hold the mount securely.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    I am not sure why the Leica R 135/2.8 has been dissed? I used to have one and it was a great little lens, felt great in the hand, focused butter-smoothly, had really nice boke, and was pretty sharp. It is no APO or Asph lens, but it really doesn't need to be. I only sold it when I sold my Canon 5D. They can be had dirt cheap too.
    Carsten - Website

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Quote Originally Posted by carstenw View Post
    I am not sure why the Leica R 135/2.8 has been dissed? I used to have one and it was a great little lens, felt great in the hand, focused butter-smoothly, had really nice boke, and was pretty sharp. It is no APO or Asph lens, but it really doesn't need to be. I only sold it when I sold my Canon 5D. They can be had dirt cheap too.
    I still have it. (the Leica "R" 135mm 2.8) Got it from Kurt for under $400
    It 's great!
    (Here with DMR)
    Victor

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Note that all of these shots were hand-held with SSS on. Artistic value is close to zero on these; I was only looking to get a feel for the character of the lens. I deliberately disabled all sharpening and NR in LR 2.6 so the crops would not be misleading. In the first two captures, the chip was set to 50mm which explains a bit of the softness. I hope this isn't TMI(or TMP, Too Many Photos), but I thought it would be interesting to show a hint of the potential of this $150 lens. I'll probably be into it for around $200 by the time I replace the screws, shave the mount, and re-chip it. DOF is very narrow, as expected... the lens appears to be very sharp by f4, other than that settings between 2.8 & 11 seem to impact bokeh more than anything else.

    Here is the first of a couple shots I took where I noticed the color fringing(These first two captures were at f8; the other captures I took around the same time don't show anything interesting about lens performance):


    An example of fringing from the top right:


    An example of fringing from the center:


    Second pic from first session:


    Crop from near the center showing color fringing... BUT... check out the detail on the spider web!
    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Here is a series that I shot to get a feel for the bokeh at close focus, about 6 ft away(typical enough for portraits). Note that with more careful exposure, color fringing seems to be absent. Accompanying each shot is a center crop of the point I was focusing on. All photos from this point on were processed with "Auto-Tone" in LR (which I generally don't use) to cancel out the usual "chipped MF lens" exposure variation and get a consistent look for the images. On to the images!

    f2.8:



    f4:



    f5.6:



    f8:



    F11(1/30 sec; bad motion blur):

    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    This series was intended to get a feel for DOF and sharpness, composed to guarantee that some part of each image would be in perfect focus. I need to install my Type-M screen, but will wait until I get closer to having this lens ready for play. Also shot at a typical portrait distance, about 6-7 ft away.

    f2.8:



    f4:



    f5.6:



    f8:



    F11(1/30 sec; bad motion blur):



    If you think this is bad, you should see what I go through testing a new zoom. 8>) Actually since I was most interested in bokeh I was very casual about the whole exercise. Once I have the lens mechanically "ready" I will perform some more careful experiments using a tripod and more suitable subjects.
    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Were these on a tripod with mirror locked up? If so, what tripod and head? I swear I see motion in some of them...
    Carsten - Website

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Quote Originally Posted by carstenw View Post
    Were these on a tripod with mirror locked up? If so, what tripod and head? I swear I see motion in some of them...
    As I mentioned in post # 10, all were handheld. I assumed that the lens is capable of good sharpness, and figured that I could evaluate that well enough in the shots at 1/1000, 1/500, etc. Also mentioned above, I was most interested in how the bokeh rendered, and whether I could get away from the fringing consistently. In a nutshell I wanted to get a rough sense of whether the "character" of the lens merits putting more work and $ into it. I think it has a lot of potential and will do some careful testing(e.g. tripod, MLU) once I have the lens sorted out.
    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    I still think for a few hundred more the Leica is a better bet. I DO like Contax lenses (I have ALL the 645 and the CY 21/2.8) but this seems a bit lacking at the edge/corner.

    How is the focus? The Leica I was surprised was smooth (I do think it is a CA lens though)

    Where are you? I am happy to send the lens for you to compare (I am NOT selling! :-) I have Leitax to Pentax and am ordering a Leitax to a for my 400/6.8. May try it here.

    Victor

    PS Anybody want to lend me a A900?

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    Re: Contax/Zeiss 135 2.8 conversion to a-mount

    Victor, the focus action is not only very smooth but also very tight and well-damped. By "tight" I mean no play; it turns very easily. It has a very nice focus action, but the aperture ring was a bit loose. I opened it up and the mount was shimmed with bits of what appears to be that adhesive-backed aluminum tape used in ductwork. The average shim thickness was about .65mm(by no means consistent, was .12mm or so) and it seems that what is needed is about .25mm of shim to make it fit right, leaving about .05mm of play. If I had a second aperture-detent plate to drop in it would be near perfect.

    On top of that, the mount itself has been filed down unevenly -- and I mean filed by hand. I'm going to get the mount on a lathe and get the surface that contacts the frame of the lens turned down just enough to ensure that it is flat and parallel with the surface that contacts the body. At the same time I can probably have the edge relieved to clear the aperture ring rather than shimming it.

    Addressing these issues ought to get the lens about .45-.55mm closer to the sensor plane, and I can fine-tune infinity focus from there following some instructions that I found elsewhere that allows me to effectively adjust the fore-aft location of the moving elements when I hit the infinity stop.

    For now I just have it assembled with zero clearance at the aperture ring, so it is essentially locked wide open. I'll snap a couple more shots when I have daylight and see where that leaves me.

    I'm no expert on optics -- just an enthusiastic hobbyist -- but I would think that having the optical axes of the lens and the camera misaligned would not affect edge sharpness but would instead cause the point of sharp focus to be closer or further away than at the center of the frame. So I'm assuming that the softening at the edges is inherent to the design, but the way I intend to use the lens I can get by with it. I'm thinking nature and maybe the odd portrait shot where the edges are far out of focus anyway.

    The offer of a loan is very generous, thank you; I'm in NorCal, Sunnyvale specifically. Where are you located? More importantly, what mount does the lens have? Currently I am only equipped to handle A-mount, T-mount, and MD/MC lenses on my a900. If this is workable I'd be happy to do side-by-side shots, using my battleship tripod, MLU, cable, etc. and a better target.

    If we are ever in the same area you are absolutely welcome to shoot my a900 and any lenses you want but with most all of my eggs in this one basket I'm not in a position to loan long-distance. I know where you can rent one though... try alphalensrental.com. Matt seems like a good guy, I have enjoyed doing business with him. Last I contacted him about 2-1/2 weeks ago he was a day or two away from moving to the West Coast and he still hasn't updated the status of gear on his site, so he may have it in stock.
    α900+VG|F20|2xF58|16-35,24-70,135Z|STF|70-400G|50,85 1.4|16,20,28,100M,80-200APO f/2.8|28-135|500f/8|1x-3xMacro|2xMFC-1000|Tiltall+RRS, Bellows, etc.

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