Disassembly – Leica Summilux-M 50mm F1.4 ASPH. 11891 lens

Today I’m partially disassembling one of top quality 50mm lens – a famous Leica gem Summilux-M 1:1.4/50 ASPH. This lens copy works optically perfect and producing very sharp, contrast and detailed images. However years of intense use require closer inspection of the focusing mechanics that has some very minor focusing ring play, and since it’s no more under Leica warranty I’m starting quite challenging discovery of safe disassembly process. This lens sample is generously provided by Dale Tu (thank you very much Dale!) in a purpose of investigating its mechanical conditions, and also sharing this experience with you.

Leica Summilux-M 50 F1.4 ASPH. is very compact (though feels quite heavy for it size) and is build using high end materials and crafting techniques. It will be very interesting to have a closer look and learn more about various engineering decisions. I’m also curious how is it different from mechanics of many times less costly Voigtländer and Carl Zeiss lens.


First step is to find cross-shaped screwdrivers that properly fit Leica bolts. Yeah, even bolts are crafted with extreme precisions, and each bolt head has two dot marks, which are probably indicating screwdriver bit type, and can also serve for easier tracking of the rotation angle. If you don’t have properly fitting screwdrived, it’s time to visit few shops and find a good one.

It took me few minutes to try multiple “phillips” screwdriver bits until I found one that has perfect match. Leica Summicron-M 1:1.4/50 has built in hood, and you need to elevate it frst, then accurately unscrew single black bolt. I’d highly recommend to take notes and put every unscrewed bolt in marked place, so during reverse assembly you put exact bolt to its original place. They have different colors and lenght, so it’s important to memorize each action for proper assembly.

Now I’m removing front ring with filter thread and hood.

At this point you can also dismount hood for cleaning from the front ring by removing three white plastic cylinders (I’m skipping this step).

Next step is to accurately unscrew three silver bolts. These bolts are very short and secured with little amount of glue, but can be unscrewed relatively easy. Just be very accurate, I don’t think it’s possible to find a replacement of Leica bolt, so if they don’t rotate – use one old trick to loosen the glue first. Power on low-temperature soldering iron, then heat up the bolt head a little for a second or two (do not overheat) – then it will screw out easy. I didn’t have to do it while unscrewing bolts on Leica Summilux-M 50mm, and sharing it just in case, because these bolts are beautiful and expensive and require extra care : )

Then remove ring with lens name, and note that it should be later assembled back with white engraved dot on it to fit aperture indicating position.

Then unscrew two silver bolts holding aperture ring.

Now remove aperture ring and loosen the brass securing ring by gently expanding its diameter. Then accurately slide it up and remove.

Now when aperture controlling ring is not secured, slowly elevate it up and also remove.

Note, the removed ring has perfectly machined aperture click-stops. In the opposite inner diameter area there is also a rectangular socket to catch the aperture lever bolt (not pictured here, but listed on one of pictures below).

Next step is to unscrew TWO black bolts on the focus ring of Leica Summilux-M 50mm. These two bolts look different than other bolts unscrewed before – they don’t have two marks on bolt heads, though same screwdriver worked just fine.

Now I’m removing external focusing ring.

At this point it is also possible to unscrew the focusing knob from focus ring if you need to replace or repaint it, or just curious to see how it is made from other side (I’m skipping this step).

There are plenty of things to note there, so I’m marking them with numbers:

  1. Internal focusing ring frame has separate thin brass ring under it (which can be removed). This ring can be slightly rotated to precisely fit the position of the external focusing ring – to perfectly position infinity mark indicator when focused to infinity.
  2. There is a spring loaded metal ball (or pin ?) that is performing aperture clicks.
  3. There are three bolts with flat thread head that are most likely serving for optical calibration and securing position of the lens core.
  4. There are also three “allen” head bolts deep inside tunnels, which are most likely also serve to precisely calibrate and center optics.

WARNING: DO NOT touch that bolts 3. and 4. , otherwise you may ruin perfect optical centering of lens and cause significant image quality degradation. Well, I don’t know for sure, but intuition tells me that it can be a calibration system. Of course I can be wrong, and that bolts may serve another purpose, but I’d not experiment with $$$$ lens by just guessing, so just keep that bolts untouched, please.

There is also set of four black bolts under the massive brass ring. I’d assume that they are securing whole top lens frame. At this point I don’t have direct access to unscrew them, and also I’d not do that without knowing if that may cause optical miscalibraiton. My disassembly purpose here is only connected to inspecting focusing mechanics, and these bolts are not part of that.

There are four small holes marked with “1.” below, and by looking at them I can say that inner silver/chrome cylinder has a large thread, that is screwed into upper brass cylinder. Perhaps Leica engineers are using special wrench to separate these two cylinders, which may provise further access to bolts that are screwed into upper brass ring (displayeed above), and also two silver bolts which are screwed in bottom area and providing access to the focusing mechanics.

“2.” below is marking the aperture lever bolt, that need to fit the internal aperture controlling ring during assembly.

I’m stopping my disassembly journey of Leica Summilux-M 50mm F1.4 ASPH. at this point and assembling everyhting back in reverse order. Perhaps at some point I’ll learn somewhere how to properly separate two inner cylinders safely, and will be able to access and service focusing mechanics properly. All I can do here is to add a little fresh grease to accessible edges of focusing helicoid threads and brass helicoid guiders (by the way one helicoid guider has small flat head bolt in its edge – fascinating!), which is resulting to more smooth focusing ring rotation.

I’m not covering the rear area disasembly in this article, because after unscrewing 6 bolts and removing mount ring there is nothing to do safe. Furhter step there requiring to unscrew two small brass bolts that are supporting radial rotation of rear lens optics during focusing, and probably extracting rear optics module from its thread which will open access for dust inside, and I prefer not do to it without very serious need.


I have to say that the high quality and extreme precision of all machined parts is impressive, even though I knew that Leica products are of top quality – it is very different to hear about versus checking things in person. The build quality is outstanding and the best I ever seen.

You could notice that performing disassembly steps of external lens frame happen to be very easy once they are discovered. This Leica Summilux-M 50mm 1:1.4 ASPH. lens is beautifully engineered with high serviceability level. It’s simplified process of quick replacement of any externally damaged part, or in case you need to do some re-painting.

External rings are all made of lighter metal but look very strong and fit to each other precisely. All internal core is assembled of extremely durable looking brass parts which should serve for a lifetime and longer.

The assembly process went easy and safe, and now lens is focusing smooth again, and ready for taking new pictures.

Please let me know if you have questions on this disassembly, or more important – if you have some knowledge or hints that could help to move forward with safe dismounting of inner cylinders and continue the disassembly. I’d be glad to continue with this process and share more details in this article.

UPDATE: just next day after posting this article I’ve received extremely useful link shared by Leica Forum member labyrinth (thank you!). There is an article on GIGANTOPTIK.COM BY GOLIATHUS that is exposing process of Leica Summilux-M 50mm f/1.4 ASPH. disassembly and CLA with lots of detailed pictures. I’m going to explore it this week and see how i can move forward with focusing mechanics disassembly.


  1. Great photography and great skills with the work completed. Thanks for sharing this for all to see.

    The link you posted (gigantoptik) was an incredible disassembly!

    I wish I understood the part in that post where the lens had “optical axis correction work completed” as that part seems to be of the upmost importance.

    Anyway, thanks again I saw your post on LUF and I’ve now read a few of your articles and they’re all clear and concise.

    (Not sure I’d ever attempt this stuff… I’ve greased some helicoids in my life, but I’d hesitate big time to start removing elements and aperture blades!)

    Thanks again

    Liked by 1 person

    • Thanks for interest and feedback Adam. Regarding optical centering performed by Goliathus in that linked article, looks like there are three calibrating “Allen” or “Torx” bolts that allow very precise shifting of the front optical module. If you point lens to a testing target, like Zeiss Siemens Star Chart, it will show you what is decentering direciton, and bolts need to be adjusted from that side, until module is perfectly centered by showing perfect circles of test target defocused image.
      You can search for related useful articles on Lensrentals blog.


      Liked by 1 person

      • Thanks for that info Yuri,

        It’s good to know, but I can’t imagine I’m going to try it!

        Sometimes I wonder if my ‘Lux is such a good copy… in silly not real world usage tests (like shooting wide open something with fine detail that’s 10 meters away) I don’t think it resolves detail very well, and it can be a bit glowing…

        …but I’m very sure that if I try to take it apart and adjust it then afterwards it will definitely have a problem!

        Thanks again

        Liked by 1 person

        • You are absolutely right Adam, I’d also NOT perform optical collimation, unless there are no other options. That process is quite complex and requires specialized equipment with lasers, sensors, software, tools, test stations. Of course with proper level of skills DIY optical collimation may deliver decent precision results as well, especially if it’s a whole module centering (so you don’t have to rotate individual glass elements). And yes, it is extremely easy to make optics work worse and not being able to correct that.

          I think your lens sample should perform just great. There are multiple ways to check if it is properly optically centered and you can find great articles describibg more scientific approach of doing such tests. However if you discover that lens needs optical centering – the best decision is to send it to a service center.


          Liked by 1 person

          • 100% agree Yuri,

            I don’t really really see any problems in normal usage, nor comparing sample images I see online to my own.

            The ‘Lux is quite a fickle beast IMHO, the plane of focus is not flat (like on a summicron or planar), there’s the famous ‘midzone dip’ as well.

            These things do make it a bit of a lottery when using a rangefinder for anything other than dead centre compositions.

            The T-Stop on the ‘Lux is also very high, which means that one must pay extra special attention to the exposure

            Of course when so many folks on the ‘net make claims such as “best 50mm ever made and the most perfect 50” there’s always a degree of disappointment when the images aren’t always the best and most perfect!! 😀

            But there’s no free lunch so I think to get A grade images from the Lux means you need to bring your A game when using it

            When it comes to cameras/lenses (and other devices!) I’m old enough to have learnt it’s best to let the problem manifest itself, rather than trying to find it!

            Thanks again


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