Minolta Lens compatibility with Zhongyi Lens Turbo II focal reducer

Discussion in 'Adapted Lenses' started by Kirkp, Nov 2, 2014.

  1. Kirkp

    Kirkp TalkEmount Regular

    151
    Nov 2, 2014
    I posted the following at Flickr, then thought I'd have better luck here...

    I recently purchased a Mitakon/Zhongyi Lens Turbo II 1508 focal reducer to adapt Minolta SR mount lenses to a Sony E-mount camera (NEX-6). I was immediately surprised to learn that there is mechanical interference between the glass element of the Turbo II and some of my favorite Minolta lenses. This seems to occur on any lens that protrudes the slightest distance behind the bayonet when focused to infinity. This is the case on Rokkor 28mm f/2.8 and 50mm f/1.4 and f/1.7 lenses. I don't think it occurs on telephoto lenses. It's also not a problem on a Rokkor 45mm f/2.0. I'll need to check a few more lenses, and I guess I'll need to put stickers on the lenses that turn out to be compatible. Otherwise I may grab one that isn't compatible when I'm in a hurry and cause damage to the lens and/or focal reducer. I don't think there is a solution to this other than avoiding those lenses. Unfortunately, it was those wide and normal lenses that I most hoped to use with the focal reducer.

    On a few lenses, the depth of field preview lever contacts the metal lens surround of the Turbo II, causing the aperture to jam open. I had heard reports of that before, and observed it on at least one lens. I'll need to shorten those levers with a file (taking care to avoid leaving filings in the lens!).

    I'd like to hear from anyone else with similar issues or links to discussions. It anyone aware of a list of compatible and incompatible lenses?
     
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  2. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    The Metabones Minolta MD to E mount speed booster actually has the same issue.

    I ended up shortening the levers using pliers, which was tricky and risky.

    I didn't need to modify the MD Rokkor 50mm F1.4 or the MC Rokkor 80-200.

    I did have to modify the MD 35mm F2.8, the 85mm F2, MD 35-70 Macro and 24mm F2.8
     
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  3. Kirkp

    Kirkp TalkEmount Regular

    151
    Nov 2, 2014
    Hello Jai,

    So the Metabones only has an interference problem with the depth of field levers? It doesn't have a problem with the glass element contacting the back of the lens?

    The glass element in the Turbo II has a very convex shape. I wonder if the Metabones is a little flatter, so doesn't protrude as far toward the back of the adapted lens.
     
  4. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    Yes, it's just the depth of field levers that clash, so that the aperture is forced wide open.
     
  5. mork

    mork New to TalkEmount

    2
    Nov 7, 2014
    Hi,

    i've the same problem with LT II model NEX 1706 and several Minolta lenses, using a NEX5N.
    Rokkor 58 1.2 (it is the reason why i've bought the LT II): LT II screws in very smoothly (it is the most "easy" and a bit loose fit among my lenses) but diaphragm won't work...you'r stuck WO. Only way to use it with other F.stops is to unscrew a little bit, making the combo VERY unstable and risky.
    Rokkor MD 135 2,8 :sometimes as above (58 1.2) and sometimes works perfectly....i still haven't figuered out what's the correct way to mount, it's pretty random....this lens is SUPERB with LT II
    MD 28 3.5...The LT II works fine...and the lens become very nice (it was one of my less loved lenses)
    MC 28 2.5: rear lense protrudes too much, you can't focus infinity.
    Tamron 17 sp 3.5 adaptall II minolta md: it would focus to infinity with no trouble but diaphragm is stuck WO (real shame!!) unscrewing a little bit frees the diaphragm...the frame can be sharp corner to corner by f8-f11. What you notice versus the not LT adapter is the spherical aberration that increases a lot..but overall i think it's pretty usable as wideangle (i'm comparing it with sony pancake 16 2.8)
    50 1.4 MC: works fine, the mounting is pretty smooth and precise, as the removal.

    I'm a bit afraid about shortening the pins on the rear of the lenses which are not working correctly...what if it will cause troubles with other adapters, in the future?
    Would it be possible to buy other pins on ebay or steal from old broken lenses instead and substitue the originals to avoid messing up with them?
     
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  6. Kirkp

    Kirkp TalkEmount Regular

    151
    Nov 2, 2014
    I don't think slightly shortening the aperture lever on a Minolta lens just enough to eliminate the interference would cause it to be incompatible with other Minolta gear. After all, your other lenses that don't interfere must have shorter levers. My main concern is to avoid damaging the lens when making the modification.

    The mechanical interference between the glass elements is a much greater concern to me. Mounting a lens that bumps the glass when focused at infinity could easily damage the focal reducer. I can't think of a workaround for that, other than avoiding use of the lenses that protrude behind the bayonet when focused to infinity.
     
  7. jai

    jai TalkEmount Top Veteran

    589
    Feb 4, 2013
    I have managed to shorten the lever on a bunch of lenses, without damaging the lens. But then, I decided I wanted to use the lenses of Minolta film cameras, doh! I managed to extend the levers again, till they were at just the right length so they worked with Minolta film cameras but didn't interfere with the metabones speed booster.

    I don't think you can file down the lever, or cut it off with a mini hacksaw. It just moves around too much. The technique I settled on was using the wire cutter part of my pliers. It took a considerable amount of force, and obviously you still need to be really careful.

    Then, when I decided I had cut it too short, I managed to extend it by mixing up some araldite, dabbing a bit on the lever and holding the lens facing up so as the araldite would slowly drip down and harden.

    I suspect this kind of thing probably ruined the re-sale value of my lenses, but hey, I plan to keep them.
     
  8. mork

    mork New to TalkEmount

    2
    Nov 7, 2014
    I've just managed to make the Tamron work, with a bit of dremeling on the pin.
    I've risked that shortening because the tamron got an adaptall 2 to minolta ring at its end, a very common mount which i can substitue easily.
    I'm not going to do that on my shiny 58 1.2...too beloved to be tortured that way, then i wouldn't have a substitue for the mount in case anything would go wrong....

    Better to wait for the a7 II full frame (it will come, sooner or later...), enjoying then the not-damaged lenses....


    There is also an other issue which is stopping me: my 58 1.2 has a different pin by the other minolta's ...it's sort of "L" shaped, instead of a cylinder....not so easy to be shorten as the normal pin....
     
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  9. AK47J

    AK47J TalkEmount Veteran

    231
    Jan 31, 2014
    Central Oregon
    I also have a Lens Turbo 2 in MD to nex. I have been using it with my Rokkor 50/1.2 , 28/2.8 and 135/2.8 without any issues. I have acquired more Minolta MD mount lenses over the months. Today I tried to mount them to the LT2. All of them mounted, but none of them would focus to infinity, and the apertures were stuck open. These lenses are 50/1.7, 58/1.4, 35/2.8 (both an old and newer version). I am disappointed that I am not able to use those lenses on the LT2, but I do not plan on modifying any of them to make them work. I will just use a standard adapter if I feel I need to use them. Primarily I wanted the LT2 to use with the 50/1.2 and 28/2.8 anyway.

    How to we warn other photographers about this interference problem? Is there a way to identify problem lenses by serial number, model, age? Or is it simply a matter of looking at the rear element to make sure it does not protrude past the mount? I'd hate to have someone buy a Lens Turbo, slap on their favorite lens and damage both.