Repair: Nikkor-S 50mm f/1.4

Hello, everybody! It is a cold morning here in Tokyo so I am not in the mood to go out or do anything outside my cozy room unless I have to. This gave me the time to spend with my daughter and wife as well as to update this blog.



In this post I am going to share my repair notes for the Nikkor-S 50mm f/1.4. Before this got into my collection I have always hated Nikon’s 50mm f/1.4’s because of my previous experience with the 50mm f/1.4 AF-D. I have used that lens for years and frankly, it is a lens that I cannot use wide open.

The 50mm f/1.4G succeeded the previously mentioned lens and while it has fixed most of the optical problems of it’s predecessor, this lens has introduced a new problem into the Nikon 50mm f/1.4 family, mainly slow autofocusing and considering it’s price at that time I can say that it is not a lens with good value.

These experiences have tainted my impression of every 50mm f/1.4 Nikon has ever made, which led me to the purchase of Sigma’s amazing 50mm f/1.4 “ART” lens. Finally, I have a 50mm f/1.4 that I can shoot wide open and with amazing autofocus performance,too!

These days, I shoot manual focus lenses everyday and the need for a manual focus 50mm f/1.4 Nikkor became obvious. I went junk hunting and found 2 Nikkor-S 50mm f/1.4 that I could add to my collection (one served as a source for spare parts).

Thankfully, like most similar pre-Ai Nikkor primes of it’s class the assembly was pretty straight forward and the engineering was precise. It was not a pain at all to disassemble and put back but there are some things that you should take into consideration and we will start discussing them now.

Before We Begin:

If this is the first attempt at opening a lens then I suggest that you read my previous posts regarding screws & driversgrease and other things. Also read regarding the tools that you will need in order to fix your Nikkors.

I highly suggest that you read these primers before you begin (for beginners):

Reading these primers should lessen the chance of ruining your lens if you are a beginner. Also before opening up any lens, always look for other people who have done so in Youtube and the internet. Information is scarce, vague and scattered (that is why I started this) but you can still find some information if you search carefully.

I highly recommend that you also read my working with helicoids post because this is very important and getting it wrong can ruin your day. If I can force you to read this, I would. It is that important!

For more advanced topics, you can read my fungus removal post as a start. This post has a lot of useful information here and there and it will be beneficial for you to read this.

About Me:

I am a photographer based in Tokyo who scours the junk section of the camera shops here on a regular basis. I started this hobby of fixing old lenses and cameras because I kept on getting scammed before when I purchase online. This turned out to be a blessing because I now buy junk lenses for a fraction of the price and then fix them to add to my growing now collection. This allowed me to buy gear that were otherwise off-limits to me if I were to get them in better condition.

I was a scale modeller before who built models for other collectors for a very longtime, got an education as a dental prosthodontist (but didn’t pursue dentistry) and growing up in a watch repair shop gave me the useful skills that would help me in this craft. Fixing my car also contributed some know-how.

Having mentioned the above, I will tell you now that I am not a professional repairman! So please take what I do with a grain of salt and I will never be held responsible for anything wrong that will happen to you and your project. I hope that the pros would guide and teach us but nobody is writing anything.

As my collection of repair notes grew, I get requests from people with similar interests and from professionals who just needed some notes just in case. Now, I am sharing my library with you for your entertainment and reference. I hope that you find my work useful.

Disassembly A (Lens Barrel):

This is one of those lenses where you can remove the whole objective(optical block) from the rest of the lens without having to open the bayonet mount but this is a pre-Ai lens so for the purpose of converting the aperture ring to Ai and to overhaul the whole lens, I had to open it from the bayonet first.

As mentioned in my “Best Practices” post, before working on a lens, set the lens first to it’s rest position. In this case, turn the focus ring to infinity and always work on the lens while it is set to infinity.

IMG_1358To open the bayonet mount, you will have to remove the 5 screws that hold them in place. Just be sure that you have the correct screwdriver size and use a long shafted one because these screws are easily damaged and they are usually held by Loctite or something else.

One of the screws here should not be touched. It is responsible for keeping a tiny spring in place under the bayonet plate. I have forgotten which specific screw that is, my guess is it’s the screw closest to the bayonet lock (the tall flat head screw).

*(For earlier version with no screws on the bayonet mount, skip this step.)

IMG_1361Remove the bayonet mount from the rest of the lens and be very careful not to undo this spring. I secured mine with my wife’s nail polish so that it will not accidentally go flying across the room and lose this forever!

IMG_1363Set your aperture to f/8 or any f-number that you use for reference. This way, when you have to put your aperture ring back after Ai conversion, you know where the hole for the aperture ring is. Having done that, you can remove the screw on the aperture ring itself and the aperture ring should come off easily.

For earlier versions with no screws on the bayonet mount, you will have to remove this same screw first and then carefully unscrew the aperture ring (counter clockwise) from the rest of the lens. But before doing this, turn the aperture ring clockwise first until it has reached a point where you cannot tighten it any more. Now, count how many turns it took for you to reach that point and that should give you an idea as to how many turns you need to do when you have to put that aperture ring back.

IMG_1365Remove the 3 small screws from the chrome sleeve. Be very careful because these round headed screws can be brittle, you do not want to accidentally strip one by using the wrong screw driver size or unscrewing one from a wrong angle. The chrome sleeve should easily slide off.

IMG_1366To unscrew the helicoid off, you will have to remove the helicoid key first. To do this you have to first rotate the focus ring until the screws for the helicoid key aligns with their corresponding hole in the main helicoid. Unscrew these carefully and remove them from the lens using a pair of tweezers or just drop them off to your palm.

IMG_1368Unscrew the lower helicoid until it separates from the rest of the lens. Be careful to mark where they separate! You should also be careful not to scratch the helicoid threads with the loose helicoid key if it is still in the lens while you unscrew the helicoid.

IMG_1370Now, remove the front ring that covers the screws for the main focusing ring. This ring is fragile so be sure not to warp it by dropping it or use too much pressure on it or else your focusing will be rough.

Note: If you only need to clean the glass elements, you can skip the previous steps and start from here. You do not have to unscrew the helicoids just to clean the optics.

IMG_1373Carefully remove the tiny set screw from the front barrel. Be sure to loosen it just enough to unscrew the front barrel from the lens without the set screw touching the threads of the front barrel. These set screws area a pain so I always leave them in their holes if I can help it. You do not want to lose one or ruin the tiny 1mm threaded hole.
Removed the focusing ring by unscrewing the three flat head screws that secure it to the main helicoid. Be sure that you have marked where these screws were originally because these same screws are in charge of where your infinity mark is placed.

IMG_1377I like my helicoids to be really clean when I re-lubricate them so the helicoid stop has to go as well. Just unscrew the two screws and they should come off easily. Be sure to mark where and how they were originally placed, I had to put the front barrel back just to see how things were like.

IMG_1380The whole optical block should come off easily. Note that the screws are there so that the whole thing is held by the slot on the helicoid.

IMG_1382Now, carefully unscrew the inner helicoid until it separates and be sure to mark where they separate!

IMG_1383This is all we need to do to clean the chassis before we replace the grease in the helicoids.

Disassembly B (Objective):

This portion deals with disassembling the the objective (optical block). You do not have to do this step when all you need to do is clean the helicoids.

IMG_1391Before doing anything, go search for an illustration of the lens elements first as this will serve as your guide when re-assembling as well as help you determine wether a lens was glued to another and should not be removed and other things that will be important in any process of servicing the lens (picture from Nikon).

IMG_1387The rear elements can be accessed by unscrewing the rear barrel off from the main barrel. The rear most glass element is glued to the rear barrel by pitch and you should never ever attempt to remove it. Be extra careful not to scratch that big bulbous piece of exposed glass (the doublet)!

IMG_1390You need to use a lens spanner to remove the plate that holds that big piece of glass. That thing is called a “doublet”.

IMG_1388The front lens assembly can be easily unscrewed from the main barrel. If it is held tight by adhesives, just do the regular acetone routine and it should be fine.
IMG_1389It took me plenty of time and copious amounts acetone to safely unscrew this metal collar from the front elements assembly…

IMG_1392The front element should come off after removing the name ring (the beautiful ring in the front with all the letters and numbers engraved into it). Use a rubber stopper to remove it and use some acetone if it was being held by adhesives and you should come to the same point as the picture above.


This lens should be ideal if you just want to open up a lens and clean it just for fun. These are inexpensive and can be bought for as little as $20 from the junk shop. Doing all of this will probably take the whole afternoon. The only things that you have to be careful with is the fine threads of the front barrel, that thin metal ring on the front of the focusing ring and that annoying set screw.

I hope that you have enjoyed reading this and I sincerely hope somebody will come across this blog post before attempting to service this lens and find this helpful. Thank you very much and enjoy the weekend.

Help Support this Blog:

Maintaining this blog requires money to operate. If you think that this site has helped you or you want to show your support by helping with the upkeep of this site, you can simple make a small donation to my account ( Money is not my prime motivation for this blog and I believe that I have enough to run this but you can help me make this site (and the companion facebook page) grow.

Helping support this site will ensure that this will be kept going as long as I have the time and energy for this. I would appreciate it if you just leave out your name or details like your country and other information so that the donations will totally be anonymous it is at all possible. This is a labor of love and I intend to keep it that way for as long as I can. Ric.


43 Comments (+add yours?)

  1. orangeelephantphoto
    Jan 23, 2016 @ 13:39:56

    Thank you. Another fascinating & instructive article.


  2. doc a
    Jan 23, 2016 @ 17:30:33

    Ang dami bang junks dyan? Ang galing naman…wala akong ganon ka tyaga…thanks for the effort to share this.


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  4. carlo
    May 23, 2016 @ 14:26:24

    Good morning!!! Or read with great interest your article, I would like to change in AI but this goal has not the screws that usually serve to dismantle the union of optical coupling, can you show me how to disassemble this ring? Thanks for the help they want to give me.


    • richardhaw
      May 23, 2016 @ 14:34:01

      Buon Giorno, Carlo!
      So you have a 50mm f/1.4 without the screws on the bottom? Can you please give me the serial number and maybe I can help you. If your serial number is OK then maybe you do not need to convert it!


  5. Lev
    Aug 24, 2016 @ 15:47:17

    Thank you for the guide! I just got one 50mm/1.4 from KEH with that 1mm set screw damaged that prevents focusing closer than 2.5 feet. Can I just remove it and use a small drop of a nail polish or some other weak glue to keep the silver front ring in place? Thanks!


    • richardhaw
      Aug 24, 2016 @ 23:28:53

      Hello, Lev!
      I don’t get it. Is that set screw getting in the way of the front ring? Sometimes, that thing will sink in diagonally. You can just remove it and use nail polish like you said to secure it. You can even skip the glue if you opt to. Ric.


  6. Lev
    Aug 24, 2016 @ 15:52:10

    Another question: To AI my old Nikkor-S 50/1.4, with no large 5 screws at the bayonet, do I need to remove the bayonet that is held by 3 small screws connecting it to the back barrel before I remove the aperture ring? Thank you again!


    • richardhaw
      Aug 24, 2016 @ 23:32:01

      Hi, it seems that you have the earlier version. Is that the version with the scalloped aperture ring or not? If it’s the fluted aperture ring then you can just remove the bunny ears and that will slip under the aperture coupling tab in the camera so you do not need to convert it to Ai. Check first and then I will show you a simple way to convert it to Ai non-destructively. Ric.


      • Lev
        Aug 25, 2016 @ 11:51:06

        Hi Ric,
        My 50/1.4 are from 1960s Nippon Kogaku Nikkor S: one 6-blade, another is 7-blade, both serial numbers are in 400000’s but aperture ring looks the same on both, I think you call them fluted. The second one (was “broken” due to the set screw damaged) has a small notch already filed under the “bunny ears” prong (it is probably the conversion you meant). However, I want to use it with my N80 film camera that I still use sometimes, so it needs a more thorough filing including removal a part of aperture ring at 8 o’clock. Also, I need the prongs to use my 2x converter with this lens. So how can remove the aperture ring to file it?
        By the way, what solvent would you recommend to remove oil from inside the lens, both from the glass and aperture elements? Thanks a lot!

      • richardhaw
        Aug 27, 2016 @ 06:13:07

        Hello, Lev.
        For lenses like that, first you have to remove a screw in the aperture ring and simply unscrew the whole aperture ring off. It may take 7-10 turns because the thread is very fine.
        For oil in the aperture blades, I use lighter fluid on lens tissue to wipe the blades one-by-one. Some people will simply wipe them without disassembling it, that is fine but it is the lazy way to do things. For the glass elements, I use alcohol but lighter fluid should also be OK.Just be sure to use the right type of lens tissue. Ric.

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  10. Paul del Rosario
    Feb 01, 2017 @ 08:49:19

    Great article. Do you have a recommendations on how to repair / service the Mechanical Diaphragm Lever on this lens? I just got one, and it doesn’t have that “springy” feel. When I push it up or depress it, it just stays in that position; it doesn’t spring back. Needs oil?? Something too tight?? Advice greatly appreciated.


    • richardhaw
      Feb 01, 2017 @ 09:57:15

      Hello, Paul.
      Please check and see if you have an oily iris, that will make that thing stick but there could be more problems. The spring inside is anchored in a very inconvenient place. Ric.


    • richardhaw
      Feb 01, 2017 @ 14:22:30

      Hello, Paul. My studio is in Shinjuku, I can take a look at that during lunch break, just tell me when so I can bring my driver. Take a look at the iris from the front and from the back. Make sure the lens is stopped all the way down and see if there’s any trace of oil in the blades. Ric.


      • Paul del Rosario
        Feb 01, 2017 @ 14:26:53

        Hi, Ric. I’m on the Chuo Line, so Shinjuku is not a problem.
        Yes, I do see oil on the blades on the front and back sides.
        By the way, please don’t go out of your way for this if it’ll take a long time; but, of course, any help would be much appreciated either in person or via this blog.

      • richardhaw
        Feb 01, 2017 @ 14:32:05

        Hello, Paul.
        If that’s the case then you have to clean the blades properly. This lens has to be overhauled or the oil will come back. Just ask for a refund if you got this recently. Ric.

      • Paul del Rosario
        Feb 01, 2017 @ 14:38:12

        Hi, Ric. Unfortunately, I got it on Yahoo Auction (no claim, no return)…. Also, it’s in in good shape cosmetically, and I don’t want to part with the Nikon F that it came with.

        Reading your article, and seeing other tutorials online gives me motivation to DIY overhaul this piece of glass. I just need to get some of the proper tools.

  11. Henry
    Mar 07, 2017 @ 07:58:11

    Hi Richard, I tried to take the aperture ring off — unscrewed the small screw on the side and kept turning it but it wouldn’t come off. It just comes around. I believe my version has a retaining ring which is the only thing that is different from my other 50mm 1.4. If I get that retaining ring off will that free the aperture ring?

    This is the description of my lens: Nippon Kogaku Japan No. 553433 NIKKOR-S Auto 1:14 f=50mm.

    Thanks in advance.


    • richardhaw
      Mar 07, 2017 @ 11:56:54

      Hello, Henry!
      I will check my notes later when I get home for all versions of that lens. I don’t believe that it’s being geld by anything other than the screws. Can you please show me a picture of what you have? If you are referring to the brass ring you will have to remove a tall head screw that is connected to it outside of the casing. Ric


    • richardhaw
      Mar 07, 2017 @ 23:54:49

      Hello, Henry.
      It looks like there is a retention ring there. Ric.


  12. Henry
    Mar 08, 2017 @ 14:32:29

    Thank you. I’ll try and get the retention ring off when I have the right tool for that job.


  13. Henry
    Mar 09, 2017 @ 09:45:56

    Thank you. Ordered a spanner wrench already, I should get it soon. Thanks again.


  14. effclef
    May 05, 2017 @ 21:00:36

    Hi Ric,

    I am fascinated by your site. It encouraged me to clean and lubricate my own lenses. I am having a problem with my Nikkor-s 50 1.4. It is a late 60’s unit with no screws on the focus ring, so I am attempting to disassemble it from the rear. However, the aperture ring will NOT come off. I havent run into this with other Nikkors…any ideas?


    • richardhaw
      May 06, 2017 @ 01:48:41

      Hello, Steve!

      I made an article about that, you can do a search. It is one of the earlier ones that I wrote. The aperture ring screws off in that version. Please read other related articles just in case. Ric.


  15. Ben
    Jun 16, 2017 @ 10:46:08

    Great article Rick!


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  17. MarkP
    Jul 27, 2017 @ 03:08:30

    I got one of these in a bargain bin — terrible fungus and rough focusing. I can’t figure out how to get the objective out the front. There is the tiny screw on the side but the focusing ring is blocking it. No screws on the focusing ring?? Am I supposed to twist off the beauty ring on the front to get access to more screws?


    • richardhaw
      Jul 27, 2017 @ 04:07:03

      Can you give me the serial number? If you have this kind of lens then you may have to remove the focusing ring first. Check my 5.8cm repair article, that lens has more in common with that.


  18. markanthonypino
    Jul 28, 2017 @ 02:23:59

    I’ll check it out. Thank you. Nikkor -S Auto 1:1.4 f +50mm 1079265. It has had a professional Ai Conversion done.


    • markanthonypino
      Jul 28, 2017 @ 02:26:42

      It looks exactly like the one in this article. I just can’t visualize how to get the front rings I can get to the lens objective and clean out the fungus.


      • richardhaw
        Jul 28, 2017 @ 07:47:33

        Hello, Try removing the focusing ring. The screw might be under that. If you can wait, I can check my notes when I get home.

      • richardhaw
        Jul 29, 2017 @ 01:45:23

        Your serial shows that you have a later version so this article should be relevant. just follow the steps here and you should be OK.

      • markanthonypino
        Jul 29, 2017 @ 12:22:41

        The screw is definitely under the focusing ring, but I can figure out how to remove the focusing ring as there are not screws on it. I’ll go back and look at the steps you posted but it isn’t clear to me how you do that part. Thanks for your help. It will be a really nice lens if I can open it up, clean the fungus and not bollocks it up.

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  20. Oskar Ojala
    Sep 15, 2017 @ 21:18:19

    I’ll add here that on my late version lens, the diaphragm spring is connected to the screw directly opposite to the rabbit ears when the aperture is set to f5.6. It’s 90 degrees down from the aperture lever so that the aperture lever moves away from the screw (which also explains how it works: the spring pulls the lever toward the screw.)


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