DIY Lens Mount Conversion of the Minolta Rokkor 58mm f/1.2

DIY Lens mount conversion, results (see below for "how to")


Here is the completed Minolta 58mm f/1.2 modification mounted on my Sony Alpha DSLR. Originally the lens is for the Minolta MC mount, which can not adapted to the Minolta AF mount "passively", i.e. any adapter would need to have optical elements to maintain infinity focus (at the expense of image quality). I managed to replace the mount on the lens itself by substituting an M42 to Minolta AF adapter for the original mount. After readjusting focus on the lens, it now aligns perfectly with the original distance scale, all the way to infinity.


While I did this for the Sony/Minolta AF system, the guide to the modification (see below) applies to any current DSLR system for which you can get a suitable adapter, e.g. an M42 to Canon EOS or a glassless M42 Nikon adapter can be used.


The lens was chosen because there is no f/1.2 lens available for the Minolta AF mount and most other f/1.2 lenses available tend to be either extremely expensive, hard to find, and/or far inferior (e.g., the Tomioka 50mm f/1.2 for M42 is not very good in my opinion). This lens, on the other hand, cost me about €100 and has bokeh worthy of legends. It is not the sharpest of lenses wide open (still, quite decent), but it has very pleasant image characteristics and is a lot of fun to use.


I recently updated this modification by installing a microchip which identifies itself as a 60mm f/1.1 lens (closest setting available at the moment). The chip was kindly provided by James Lao, who makes custom chips and M42 to Minolta AF adapters. If you use an electric adapter for the mount, the exact same guide can be used, or you can later install the microchip on the adapter (as I did).


With electronics the focus confirmation and in-camera anti-shake both work with this beast. (Focus confirmation doesn't depend on reported focal length, and for anti-shake the slight difference doesn't really matter that much.) The in-camera anti-shake of Sony DSLRs makes this a low-light photography marvel.


See the pictures beginning from here for my complete writeup on doing the modification. This method can also be applied to some other lenses, and certainly for converting to camera mounts other than Minolta AF.

  • Mitrevski 5y

    hahahaha i knew you would say that :-) well im not ready to part with them yet lol :-) I heard another guy say the same that it should be something simular to the 58 1.2, i am seriously considering it.
    Im sitting with them here and they look pretty simular in issue of distance but there is difference, i dont see any screws on the 100mm, atleast not where they are in the silver/aluminium mount on the 85mm.
    if i decide to do it im gonna make a pretty job so it looks like they where borned like that, in that case i would like them to be super acurate.
    Well see, i´ll keep you posted about it, and will send you some photos aswell if i decide on it.
    They are really beautiful and solid lenses, the way they are built really resontaes with the eos 1v.
  • phοtοcraft 5y

    @ Mitrevski - If you're just using them for portraits and nothing else, convert them!!! but don't use any destruction because you don't need infinity focus. This way you'll have your lenses in mint reversible condition and be able to do your job on some seriously good cameras.
    Just a thought.
  • Mitrevski 5y

    I appriciate your enthusiasm Michael and i was thinking the same, it could be an option, i havent use them for anything else than portraits so far, landscabes and still lifes i do with a fifty mill, or a wideangel, or a stronger tele, never with 85 and 100. The thing is that the apeture pin will defenately hit the mirror on my 1v, im afraid i have to shave off some of the pin, or the mirror in the camera, to avoid them smahing together even thoe you dont get infinity focus, i have an eos 30 laying somewhere, another option could be to change the mount on that one, the thing is just the lightmeter in that camera for some reason doesnt work when adapting lenses from other brands and its a light camera, have no idea why but i heard that this is common to earlier eos 30 model (im talking about the film camera not the 30d) But again i dont think you can do it either even thoe you use thoes mounts to change on the camera made by this italian guy, without having to shave some of the mirror off the kamera, or the apeturepin on the lens, wich makes it end somewhere the same again, and its really not my main camera i bring when travelling, its been my backup on one journey thoe and kept on in the heat of Banaras india when the 30d went on a strike for a week to suddenly work again a week after?? so its not really interesting, but again i can just mount them on one of my minolta bodies when i want to shoot a roll like i have been doing so far, but what is there to choose between beside a plastic x700? i need a solid camera i can work with seriously, that doesnt brake easily and have basic features such as a acurate lightmeeter, exposure control and high shutterspeed for shots on wideopen aptures in the strong sun of the mountains, for portraits in rural dusty areas where you want a narrow dof to isolate your subject. The main idea was to make them work perfectly on my favourite camera eos 1v and the 20d wich i use for backup and/or dokumentation/snaps (but they would probably be mounted on a 5d and 1ds aswell now and then if they where made) without having to shave the mirror in the cameras, and changing the mount on one or more of the cameras, that is out of the question cause like i said i use original lenses, and adapt other brands aswell, im a afraid it would require some shaving on the lenses themselves no matter how i do it due to the mirror in 24x36 cameras but i dont know for sure yet, and if i decide to do that i might aswell do it very properly and super acurate, and pretty. Otherwise it would be a pitty i think.
    When i look at it this way, i have the choice to put them in a glass vitrine together with other gear i rarely use for what? Then to sell of my collection when i get older? well yeah okay, its an investment as they are pretty minty/well kept, but i would rather use them, who knows if im still here tommorow :-) they are made to be used and are actually also fantastic optical performers, but the really good thing about them is their build, i travel Alot, sometimes to very remote and dusty areas, mountains and so on, the only gear that never let me down so far, have been the most solid, the stronger L tele lenses are built somewhere as decend, but not their shorter teles, mounting one of theese two rokkor lenses on the eos 1v instead of the 85L or 135L, (or the 85 1.8 and 100 2 for that matter, not far away from the build of those two L's) makes a million time more sence in my head, the two L versions i mentioned are fragile lenses, built mostly for studio and indoor use, they cant take the same beatings as theese two are able to, they just cant, and look what they charge for them, crappy company hHAhahaha here i go rambling again! :-) another option could be to swop/sell them for older leica or zeiss versions, and even thoes arent build as good but pretty close :-) thoes dont need any modification and can go with an adapter, like the zuikos, m42 ets can do and so on.

    What happends to theese people that decide to make some proper slr gear, are they totally smashed by the big companies before anyone even hears about them? When you want the best and strongest slr gear there are just one or two to choose between, and even thoes dont have perfection throughout their entire system but they are busy making it as large as possible. I could use some folks like you Kimmo to realise the ideas i have for a few projects i have in mind, would love to sit down with you some day and talk about it.

    Forgive me for rambling on like this Lol! this is a favourite alley in photography for me :-)
  • phοtοcraft 5y

    @ Mitrevski - It's cool man, we all love photography here and we understand your problem. I was only happy to do a little destruction to my lens because it was not a perfect example; there was already a 0.5mm scratch on the front element etc...
    So obviously with mint lenses there arises this problem.
    Out of all your thoughts you don't mention the possibility getting a Sony body. I think you should give it some thought, because the main thing with photography is the photographer and the lens. Most modern bodies do pretty much the same things, but only Sony (out of Canon, Nikon and Sony) will give you an Steady Shot/sensor-shift/anti-shake option on these old lenses. (plus Sony allegedly make most of the digital sensors for Nikon anyway)
    But yeah, I would give it some serious thought.
    (sorry Arkku for using this space as a forum!! ^_^)
  • Mitrevski 5y

    hahaha im so glad you actually mentioned that caus i didnt want to start rambling about it. And yes, thank you Arkku/Kimmo for creating this space, since what you talke about now Michael has to do with converting i think its okay even thoe it includes a switch to another brand etc lol. Believe me, i have thought about it, especially beaucase of the antisacke within the body (even thoe i dont need it ;-) i tell you the honest to god truth, i am able to handheld with precision on very low shutterspeeds without the use of any stabilization due to more than 20 years of shooting, even with short and normal tele lenses, but i agree, its still nice and gives you an extra push for even lower speeds :-) The reason why i dont do it and one of the reasons i mainly still shoot film mostly, is beaucase of the color space, thats also why i will choose a Canon dslr when buying one again, the 14 bit a/d converter on the processor gives a larger colorspace vs the 12 in sony's and canons earlier models, this is probably one of the most important thing in my eyes, all canon models from 1000d, 450d 40d, 1d mark 3 1ds mark 3 and 5d mark 2 all got a 14 bit a/d converter, nikon has is too in their d300, d700 and d3 and up but they are a little more complicated when it comes to convert vintage lenses as allready mentioned by Arkku, and i personly find their prices too high for their solid models (and that goes for both companies) if pentax, olympus or sony had a fullframe camera with a 14bit a/d converter i would happyli get that one, but they dont (not as far as i know) and they dont seem to plan on mounting a fullframe sensor either, caus they know that the maf (owners of both nikon and canon) would come knocking on their door to slid their throath :-l (my personal thoughts) i used both minolta and olympus before getting involved with canon some five years ago, and i allways been happy with them, i still use my om bodies sr, srt and x bodies, but not as much any longer due to the eos 1v wich is the best Camera i have ever own and worked with, it really is the best analog camera.
    Now heres the interesting thing, the nikon coolscan 5000 ed film scanner wich came in 2004 or 2005 if i rememember correct, has a 16 bit a/d converter in it, film allready got infinite tones and color nuances, so the better the scanner is, the more you can actually extract, unfortunately i dont own one, so if i where to spend alot of monney again on gear now, i would go for that over any dslr model, and just keep shooting good film like vevlia, astia, pro plus an delta pro with my 1v as i allready have a fridge full of it, wich i allready do, and when i have accses to one i ofcourse use it, otherwise im doing just fine with my little plustek 7200 film scanner, and 20d for documentation/quick work here at home :-)
    Pentax introduced an aps-c camera model with a 22 bit a/d converter in it ?? yes, but it seemed to be a scam is the technology wherent able to use it so it ended up beeing 12 like the rest. Heres a link to specs on the pentax model (look at the sektion wich says image processor)
    and heres specs on the nikon film scanner (minolta's dual scan 3, scans in 16 bit a/d aswell)
  • Napolitan_2000 5y

    I wish i could find one that i could afford. I just use an x700. They are selling for crazy money now. Much more than they even sold for new, even if you account for inflation.
  • zelvis1 5y

    I just came into possession of two Mint condition 50mm f/1.2 rokkor lenses. One I will keep with my srt101 or my xd11. The other I will use as a telephoto for the time being with my lummox g1. Eventually I would like to get a full frame digital camera. Can I convert the lens for the sony a900 as described? I understand that it is not possible to change the mount for other brands or is it?
  • Kimmo Kulovesi PRO 5y

    The 50mm f/1.2 may be harder to convert than the 58mm f/1.2, but it is possible to convert it to Sony/Minolta AF mount (including for the A850/A900). Where register distance is concerned you can also convert it to Canon EF mount but if you choose that then you ought to check if there are mirror clearance issues with full frames—many converted/adapted lenses hit the mirror on 5DmkII.
  • zelvis1 5y

    Sorry, I meant 58mm f1.2 .

    As for converting for an ef mount...I just saw a video on YouTube where the owner put the rear element housing into a machinists lathe and took off about a mm of the barrel To avoid the mirror.

    I guess the difficult part is adjusting focus at infinity. Is it impossible to mount the lenses so the register distance is the same as a film camera so no further infinity adjustment is necessary.
  • Kimmo Kulovesi PRO 5y

    It's not impossible, but unless you are having a replacement mount made it's very unlikely that you'll manage it. But adjusting infinity focus is not technically difficult, only a bit time-consuming if you do it by trial and error like I did. =)
  • myparentsinindia 5y

    I do have a Minolta MD 70-210 1:4 Macro tele lens, MD 50mm 1:1.7 lens, MD 28mm 1:2.8 lens, MD 2x tele converter 300-s. All these lenses are on my old Minolta X700. Please help me to use these lenses on my Sony Alpha.
  • phοtοcraft 5y

    @myparentsinindia - you're best bet is to buy a genuine Minolta MD-AF adapter. Although relatively expensive, they're the only REAL option for those lenses as modding them all will probably (include destruction and) reduce their value considerably.

    Almost all other MD-AF adapters belong in the rubbish. (mostly the ones found on evilBay from around 15-80 euros)
  • Kimmo Kulovesi PRO 5y

    There's no good and general way to use Minolta MC or MD lenses on Sony Alpha. You can try an adapter, but all adapters change the focal length… The official (rare) Minolta-made adapter is reputedly of good quality but it is a 2× teleconverter so not very useful for e.g. a 28mm.

    I recommend you buy a M42 lenses to replace the 50mm f/1.7 and 28mm f/2.8, these are very cheap. For the 70-210mm get the Minolta AF “beercan” or a modern replacement like Sigma 70-300mm APO DG.
  • Tony Emmett 5y

    thanks for taking the time to share this with us all. inspired by your write up I've just bought a 1.4 version of this lens & can't wait to get it on my a700 :)
  • hakimi Salim 4y

    hye is it possible to convert the minolta md 85mm f2 the same way you convert the 58mm??? please need an opinion here
  • Kimmo Kulovesi PRO 4y

    Probably not the exact same way, possibly some way.
  • polarapfel PRO 4y

    Thanks for the information. But the 58mm is not available for 100€. Not even close. In a good condition, this lens sells much more expensive on Ebay, if you can find it at all. Currently, there are four auctions on Ebay running for people interested. I bet you each of those auctions will be twice as high as 100€ and more.
  • Kimmo Kulovesi PRO 4y

    polarapfel: Ah, well, this was posted in August 2007, almost immediately afterwards the prices tripled on ebay…
  • arenem101 4y

    Hello, Would it be possible to accomplish this type of conversion for the Konica Hexanon 57mm F1.2 lens to fit a Sony Alpha A350?
    Please advise,
  • Kimmo Kulovesi PRO 4y

    Definitely maybe.

    (I'm sorry if my answers to “would it be possible to convert a different lens X” are beginning to sound overly flippant, but seriously, there are a lot of different lenses in the world, often with different versions of the same lens. I have absolutely no idea how the vast majority of them are built. So I can only say that yes, in theory you can use the same kind of conversion for most SLR lenses, but in practice it may or be considerably different and/or more difficult than the conversion depicted here.)
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Taken on August 29, 2007
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