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on Oct 4, 2021 22:40:48 GMT
Last Edit: Oct 4, 2021 22:41:41 GMT by meghatas
I've just received a Yashica ML 28 mm F2.8 lens in the mail from an ebay purchase and to my surprise it barely wants to attach to my beloved Contax 139q. Unfortunately I am anything but a connoisseur of the entire history of thes beautiful lenses and cameras, therefore, there might be a simple explanation that I should be aware of, but I was hoping that someone could weigh in on why this might be happening. The 28 mm lens does fit into the camera's mount, however, I can only turn it maybe up to 1/3 of the rotation it should make, and the aperture is alway closed (this, however, could easily be a feature of the lens I should be aware of). This doesn't happen at all if I'm attaching my ML 50 f1.9 lens on the same camera, which clicks in to the camera's mount without any issues. Could anyone confirm if this is a known problem, and if so, if there's a solution to it that I or a shop could fix? I'll attach some photos of the lenses, and the Contax with the 28 mm lens mounted, and turned as far as it goes without truly forcing it. ps.: Not sure if the photos show up, but here's a link to them in a folder: image folder
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Status: Long, long time Contax and Yashica user; glad to be here and hope to contribute.
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on Oct 4, 2021 23:16:55 GMT
Last Edit: Oct 5, 2021 4:57:50 GMT by biggles3
I've just received a Yashica ML 28 mm F2.8 lens in the mail from an ebay purchase and to my surprise it barely wants to attach to my beloved Contax 139q. Unfortunately I am anything but a connoisseur of the entire history of thes beautiful lenses and cameras, therefore, there might be a simple explanation that I should be aware of, but I was hoping that someone could weigh in on why this might be happening. The 28 mm lens does fit into the camera's mount, however, I can only turn it maybe up to 1/3 of the rotation it should make, and the aperture is alway closed (this, however, could easily be a feature of the lens I should be aware of). This doesn't happen at all if I'm attaching my ML 50 f1.9 lens on the same camera, which clicks in to the camera's mount without any issues. Could anyone confirm if this is a known problem, and if so, if there's a solution to it that I or a shop could fix? ps.: Not sure if the photos show up, but here's a link to them in a folder: image folderWelcome to the Forum! I'm sorry to hear of your difficulties with the ML 28mm. I can assure you that this is not a recognised problem with the lens and it should certainly seat firmly but easily on your 139. Unfortunately, none of the photos is visible on this site but your link is working. Could you please take a couple of photos of the rear of your lens as the problem is most likely connected with the linkages on the mount. Can you open the aperture blades manually? What would be helpful is a photo from above the mount and from an angle, above and to the side of the lens with the mount visible. Hopefully we can then diagnose the issue.
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Status: Failed treatment for L.B.A. and G.A.S,
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on Oct 5, 2021 1:41:16 GMT
Last Edit: Oct 5, 2021 1:44:22 GMT by lumiworx
Welcome meghatas ... Unfortunately Dropbox no longer offers sharing of direct links to individual files for forum users, but the folder links do work as an alternative. As biggles3 noted, this isn't usual behaviour. I've never had a mounting issue with any C/Y lens from Yashica or Zeiss -unless- the lens had taken some type of damage or something came loose. It may be slight and might not easily jump out as the cause. To follow along with the question on whether the aperture is currently active and working properly... that would help to rule out at least some part of the possibility that the linkage levers/post/brackets are the root cause. With the lens off the camera, does the aperture click into all f-stops, and will it close down as expected by moving the actuator lever back and forth - just like the DoF preview would do it? Hopefully it does, and does it smoothly. There's the possibility that the aperture stop post (or L-bracket, in this case) is bent or has been knocked out of position and is binding on something. If there's any heavy wear marks or anything visually odd to get a sense of that happening, that helps to narrow down the cause. Anything, anywhere, that looks out of place can offer some tell-tale evidence of what's wrong. Another thing that comes to mind for ML lenses, is the amount of clearance each of the 3 bayonet tabs have, and if there are 'burrs' or misshapen edges or corners on the tab's leading or trailing edges. Unlike some of the Zeiss lenses, the ML's have a one-piece mount that's milled to form all three tabs and all the ridges, lock notch, etc., and if a lens were to be dropped on one of those edges or corners, it could bend a fraction of a millimeter and bind up on the inner bayonet flange of the camera that locks the lens in place. The recessed ring just under the edge of the tabs is 2mm in height. If you have a wooden popsicle stick, that's 2.1mm in thickness, and can the pushed into the 2mm gap and peel back enough wood to give you a gauge of sorts. That can be inserted at different points around the mounting ring to see if it's deformed somehow. If it's less than 2mm, it can be 'relieved' with a little gentle persuasion. :) A round toothpick measures 2.03mm in diameter at the middle, so it can offer another makeshift gauge, but maybe not as consistent or easy to judge with. Sometimes images may not offer a critical enough view with precision machined parts, and some form of measurement is needed to diagnose precision related issues. As you might guess from the figures above, +/- 0.03mm in difference is enough to cause some difficulty in getting the tabs to slide in fully without friction or binding up. I would be remiss if I didn't add that gunk and grime can solidify over time and turn into a 'glaze' that can be overly thick, and/or cause enough drag and friction to make it difficult to get parts matched up and locked together. It would be great if a simple cleaning works, but if not, it offers a chance to inspect the parts while doing it.
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on Oct 5, 2021 11:41:08 GMT
Posted: Oct 5, 2021 11:41:08 GMT
The only occasion I've had great difficulty mounting a C/Y lens was where there was evidence that the lens/camera had been dropped distorting the lens mount just enough to make mounting extremely difficult.
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on Oct 5, 2021 13:34:53 GMT
Posted: Oct 5, 2021 13:34:53 GMT
and the aperture is alway closed (this, however, could easily be a feature of the lens I should be aware of). That's because the lens isn't fully mounted. The aperture will open as the lens locks into place (check it on your other lens).
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