Modify Alpha lens mount?

Discussion in 'Sony/Minolta' started by brent_bennett, Apr 5, 2011.

  1. I have several excellent Zeiss lenses that will not work on a Sony Alpha digital camera. The registration is too close. I would like to get the A580. Have any of you heard of modifying the lens mount (machining it down to reduce the distance to the focus plane)?.
    Obviously, this would require an excellent machinist to not damage the camera. I wouild only be using older SLR lenses and therefore would not care about AF or automatic exposure. Would the camera still work ok, except for the things I have mentioned?
    If you know of anyone who might modify a standard Alpha camera lens mount, please let me know.
    PS No, I am not interested in the NEX-5. I want a good optical viewfinder, and other benefits of standard digital SLR cameras.
    Thank You for your comments and suggestions
  2. How about a Canon? They have the shortest registration distance and the widest mount throat of any APS or FF DSLR, and third party mounts are available for a lot of systems, including the popular Contax mount (which is probably what you have, if you're talking about Zeiss lenses.
    Canons also have good viewfinders. Many models have interchangeable focusing screens, which you can swap for a split image. And unlike many Sony SLR models, the Canons all meter in stop-down mode, with SLR lenses with no coupling hardware.
  3. Joseph,
    Thank you for your suggestions. I should have explained that their are no adapters for the lenses I have (Contarex) for any of the cameras that I would like to get. The difference in register is only 2mm between the Contarex lenses and the Canon, and less than that for the Sony Alpha. Your suggestions are valuable to me however, regarding the screens and the metering in stop-down mode.
  4. Can you unbolt the mount from the lens then replace with an Alpha or M42 lens mount?
  5. Yes, I could. But they are very difficult to disconnect. I would only do that if I was giving up using the film camera. It would not be practical to keep switching back and forth.
  6. What lenses/mounts? If Leitax don't sell it, there likely isn't a solution.
    Also, where/what country are you from? So I can suggest a machinist if you'd like to go that route.
  7. An alternative might be to completely take off the metal ring of the alpha mount on the sony body and screw in place a contax body mount instead. In terms of the camera working without AF or automatic exposure, as long as you make sure to leave the body in manual focus that shouldn't be a problem and with an a580 you will still be able to use aperture priority mode as well as manual exposure. I've picked up a damaged a700 body (someone dropped it and the lens mount tore loose + AF drive pin got bent out of shape) with intention to try a swap of the body mount for one of the old types of manual focus mount. I've taken off the body's alpha mount and everything still works as it should in MF mode. Haven't proceeded further yet as I'm still figuring out where/how exactly to drill some threaded holes in the a700's chassis for properly screwing on and leveling out a manual focus mount.
    One thing to watch out for with an adapterless modification of a sony body is potential interference with the body's mirror movement by any levers/couplers sticking out from the rear of your Zeiss lenses (am not familiar with contax mount so don't know if it might be an issue)
  8. Richard,
    I live in the USA. I have recently noticed a machinist in Italy that advertises lens modifications that look very good. I would be willing to send it there, but his response was that he did not work on DSLR mods for Contarex lenses. Any suggested machinists would be appreciated.
    Thank you for the suggestion on removing the metal ring on the Alpha. Ideally, I would like to do that, and it's good to hear that it seems practical to you. Not too many people look at at option like this. Your "good fortune" in finding an Alpha with damage could really help in my quest for a solution. If at all possible, I would modify the camera to not only take the Contarex lenses, but have another adapter for Sony or some other mounts (Canon, Nikon, ?) Then I couild use my old Zeiss lenses or newer lenses too. I don't care about autofocus at all, but it is good to hear from you that the aperture priority and manual exposure will still work. Changing the f/stop from to wide open for focusing to a smaller opening for shooting will be somewhat of a pain, but that is ok with me if it allows me to use these lenses. Please keep me informed on your progress.
  9. Brent,
    Glad to help. Sorry if I've mis-read something, but I'm unsure, what is the lens mount we're talking about? Contax/Yashica mount? If yes, then this is your best solution:
    If nay, then this is the guy you want to talk to. He has a very good reputation and is in the USA of course:
    I have a small workshop myself for these sorts of projects, but generally only work within the EU. Note that as I'm unclear about what mount you're talking about, I will assume this is a 35mm SLR lens and not a rangefinder lens. If it's a rangefinder, there won't be a conversion solution.
    Take care,
  10. Instead of choosing a body, somewhat arbitrarily it seems, and then trying to find some drastic way to attach your lenses to it, I would go the opposite way. I would try to find the easiest body to work with to get what you want. As has been mentioned, Canon has the benefit of shorter registration, leaving more room for adapter. Even if something has to be machined, it is better to have more leeway so that minimum amount of material needs to be removed. If even that is not enough, what about Sony NEX? Suitable adapter is most likely available, or easy enough to make.
    The Leitax modification replaces the lens mount with a Sony AF mount, so the lens only works on Sony/Minolta bodies then on, unless you take out the screws and replace it again with the original mount. OK if you want a semi-permanent conversion, but not practical if you want to use the same lenses sid eby side with your original film camera.
  11. ... or you just pick up a dynax 7/9 and shoot film :).

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