Repair: Nikkor 50mm f/1.8 Ai-S

Hello, everybody! It has been a busy week at work so I haven’t got the time to update this blog for 8 days. It’s difficult striking a perfect work/life balance here in Japan because the working hours tend to be long and can sometimes encroach on weekends so by the time you get home, you’re left with just enough time to clean yourself up and read your email. All that plus the expenses of rearing a child makes things difficult for the average person working here in Japan – No wonder people here prefer to be single all their adult life!

Having mentioned all that, I’m still grateful that I have a wonderful family who supports me in the profession that I chose and for encouraging me to maintain this blog. With the little time I have left this week, I am going to post a short but interesting tear down of a popular Nikkor that has become a favorite due to its small dimensions and the amazing cost-to-performance ratio of this little gem – the Nikkor 50mm f/1.8 Ai-S.


The Nikkor 50mm f/1.8 Ai-S has a big following because it’s Nikon’s smallest 50mm lens. It was preceeded by the short-lived Nikkor 50mm f/1.8 Ai-S (long-nose version) and this has a different optical formula if I remember it correctly. The newer lens formula is compact so its lens barrel was also made smaller. Many people consider the older lens to be better optically but not by much. If you ask me, having a smaller lens out-weigh any advantages that the older lens may have in terms of image quality because smaller lenses enable me to use them on scenarios where a bigger lens will just be bothersome.

IMG_0882The Nikkor 50mm f/1.8 Ai-S was introduced in 1980 and stayed in production up to 2005. A lens that was produced for 25 years can be considered a success if you ask me. There’s a big surplus of this lens and I remember that you can still buy these new up until some 12 years ago as “new old-stock” lenses so excellent versions of the last variant can still be found in the used market. Many people loved this lens and it’s part of many people’s kit. I personally see myself keeping this lens forever just because of its practicality.

I had the Nikon 50mm f/1.8 Series E and sold it a long time ago so I have always wanted a small pancake-like manual focus prime for my Nikons. I could buy myself another Nikon 50mm f/1.8 Series E but decided to get the Nikkor instead since they usually cost the same in the used market so there’s no sense in buying the Nikon 50mm f/1.8 Series E if you can get something better for about the same price. I think the optical formula is the same but the Nikkor 50mm f/1.8 Ai-S has better coatings compared to the Nikon 50mm f/1.8 Series E so you get better performance when shooting in contra-light.

IMG_1776As you can see from the picture, this lens has a low profile and the only thing shorter in Nikon’s lineup are the two 45/2.8 lenses like the GN Auto-Nikkor 45mm f/2.8 you see here. It’s also surprising that Nikon has packed so much in such a compact lens that the image quality of the Nikkor 50mm f/1.8 Ai-S rivals the output of much bigger and more complex lenses like the Nikkor 50mm f/1.4 Ai-S. This feature made this lens an instant hit.

IMG_9591.JPGHere it is with my Nikon FA and Nikon MD-15. The handling of this lens can be awkward if you have big hands because the focusing and aperture rings are both slimmer than the usual Nikkor. Since the aperture ring is so thin, the aperture numbers had to be closer to the camera and this can make it difficult to see the numbers properly if you are using a camera with a large over-hanging prism.

haw_5298_24028294969_oThis is the perfect travel and street photography lens if you want to be discreet. I actually find that the subjects that I shoot did not even notice me shooting at them even if I’m just a meter or so away from their faces. If I were to use the Nikkor-S 50mm f/1.4 Auto (which is twice as big) then my subjects would easily notice me and drop their heads as quick as they can and I would miss a potential shot. The fast f/1.8 maximum aperture is also great for subject isolation or shooting in low light situations.

IMG_2409.JPGI got this lens in a decent state, the glass was clean with the usual amount of dust present inside as expected from a lens of this vintage, the focusing was smooth but stiff. I can live with the dust inside but I have to do something about its focusing. I take pictures almost everyday and manual focusing with a stiff-focusing lens will tire me eventually because I need to apply more torque to twist the focusing ring as well as run the risk of damaging the rubber on the focusing ring while doing so. Having repaired many lenses before and knowing what to expect, I decided that I should give this lens an overhaul it deserves.

IMG_9637.JPGThe Nikon HS-11 is its dedicated hood and it makes it look longer when attached. This is a useful gadget to protect the front element and to shield it from stray light hitting its front element at an angle and create ugly optical artifacts such as ghosts and flare.

It’s important to know how a lens performs by doing some tests. I took the pictures using both film and digital because we need to see how this lens works in both medium. If you know a lens’ strengths and weaknesses then you will know when to use it and how. This is very important in maximizing your gear and there’s no subsitute to it but to take some real-world photos. Shooting charts and brick walls won’t mean anything if you don’t see how a lens works when used for more practical situations.

(Click to enlarge)

Flaring isn’t going to be much of a problem with this lens but ghosts can and will appear if you have a very strong light source within the frame. This can be avoided to a certain extent if you used it with it’s dedicated hood. The picture above shows how it looks when you shoot it wide-open or stopped-down. You normally won’t see this in your pictures but it’s easy to avoid this when you know what causes this.

The following sets of pictures show how this lens performs at f/1.8, f/2.8 and f/4. These are the aprtures where the lens changes its character the most and people usually shoot with this lens using these paertures. Let’s study the pictures so we’ll know how this performs.

(Click to enlarge)

Wide-open, the lens is pretty sharp and the contrast is quite good. You can find a little bit of vignetting but its fall-off is linear and smooth so you won’t notice it much. You can see a bit of chromatic aberration on very bright highlights and that’s the reason why I took a lot of pictures of shiny materials like metal. The bokeh is good but I have seen better ones from other lenses. It does have great potential and we will see that later. Its resolution is OK wide-open and it’s not at all poor. Stop the lens down to f/2.8 and you will notice a big improvement in resolution, contrast and sharpness. The vignetting is also gone and your corners will look brighter. Chromatic aberration is also gone by this point so you will not see any purple fringing at the bright highlights. The bokeh remains smooth but it’s not as smooth as it was because of the angular shape of its iris. The lens performs near its peak by f/4 and you will get really sharp photos with excellent contrast and resolution. You can see that the bokeh begins to looks “clumpy” because of the smaller aperture but it retains its smoothness and character as if it was shot at f/2.8. I don’t have any pictures here but I guarantee you that the pictures taken at f/5.6 are stunning. I have shot with this lens for a long time and I know how this thing performs at that aperture.

(Click to enlarge)

The picture of the lady was shot at f/2.8 and you can see how nice the contrast of this lens is when shot with good light. This lens also focuses really close for a 50mm lens and you can take nice product shots with it as you can see in the picture of the Nikon Df. When it’s shot wide-open, you can get dreamy pictures filled with mood. The newer coating is the key here so it’s sharp when shot at f/1.8. Older Nikkors will render this night scene with a “muted” character to it due to their lower contrast.

(Click to enlarge)

Here are more pictures that were shot with my Nikon Df. I love how this lens renders, the pictures have a natural-look to them and it certainly has that “vintage” vibe. Most, if not all of these pictures were taken wide-open and you can see that it’s a winner. This is the reason why many people still keep this lens in their collection despite Nikon introducing several replacements for this lens with the latest features like AF and improved coatings.

The following pictures were shot with my Nikon FA using Fujifilm Industrial 400 film. The pictures are all lovely and I love how this lens performs with film. This was designed to be used with film since it debuted during the film era so showing pictures that were shot with film should give you an idea as to what the designers aimed for when they made it,

FH000030This was shot using P mode so I guess the camera took it at about f/4 because of the shape and character of the bokeh. The picture is refined and there’s certainly a nice 3D feel to it. The details are sharp and the background is smooth. The foliage was rendered smoothly and there are no traces of the dreaded “2-line bokeh“. That happens when the bokeh feels like it has been “split” into 2 when an elongated object is blurred.

FH000018I love the dynamic range of film over digital. All you need to do is get your exposure right and you won’t have to adjust anything in post. The DOF is thin when shooting wide-open so you will need to be careful with your focus.

FH000023Just like the pictures that I took with digital, the lens renders beautifully with film. It can produce pictures with pleasing smoothness when it comes to the transition from what is focused to what’s not. You don’t get an abrubt “wall of focus” that hits your eyes hard like what older Zeiss lenses like the Tessar and Helios tend to produce. The effect is subtle so it adds to the refined feel of this picture.

(Click to enlarge)

Here’s the rest of the set that I shot using film. I have always thought that this lens tends to be boring but looking at these pictures changed my mind and I will certainly this lens more from now on. It’s perfectly useable wide-open and you will be surprised at what it can do when paired with a nice film stock.

I recommend this lens to everybody who likes the 50mm focal length. I don’t see why you can’t enjoy this lens and make beautiful pictures with one. They’re also cheap these days because people prefer fancier lenses with AF and VR. All of those features are useless for somebody who has a good grasp of the basics of photography and they only spoil newbie photographers so they feel inept when these features are not available to them. This lens will be more than perfect for teaching neophytes how to use a basic lens and it will also satisfy seasoned photographers who want to have total control over their equipment. It’s always a good idea to have one in your collection and I am sure that you will love these.

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. Please also read what I wrote about 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 novice. Before opening up any lens, always look for other people who have done so in Youtube or 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 it’s very important and getting it wrong can ruin your day. If I can force you to read this, I would.

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.

Disassembly (Main Barrel):

The main barrel of the lens is simple but the cramped internals may be a bit intimidating for those who are new to this. Being an Ai-S lens, Nikon has employed lots of clever short-cuts in this lens to cut cost and make it compact. It’s common-sense to take as many notes as possible since this is more complicated compared to your usual Nikkor prime. There’s a few things that you should be aware of and I will show them to you in this article.

IMG_1324First, remove the 3 screws that secure the bayonet mount to the lens barrel. Read what I wrote about how to remove bayonet screws so you won’t strip the heads of the screws. Do not use phillips screwdrivers for repairing Japanese equipment, they JIS screwdrivers!

IMG_1325The bayonet mount and the aperture ring should come off easily. Be careful not to bend the aperture claw that comes in-contact with the aperture assembly on the objective.

IMG_1326Next, turn the focusing ring until you see this tiny set screw. Loosen it just enough so that it doesn’t come in contact with the thread underneath it.

IMG_1328Get a rubber stopper and turn the front barrel counter-clockwise to loosen it. Make sure that the set screw mentioned in the previous step is loose enough to allow you to remove the front barrel. You can remove the set screw if you wish but make sure that you never lose it.

IMG_1329The front lens element is exposed once you removed the front barrel so make sure not to scratch it.

IMG_1330Remove the screws securing the chrome grip and it should come off like this. Sometimes, Nikon would apply adhesive to this part and you’ll need have to apply solvent to this area to loosen it up before you can remove this. The chrome grip also acts like a helicoid stop just like the one on the Nikkor 85mm f/2 Ai-S that we did on our previous lens tear down.

IMG_1331This step is very important so please mark where the infinity mark is in relation to the rest of the lens. Be sure that the lens is focused all the way to infinity when you do this.

IMG_1332In order to remove the outer helicoid from the rest of the barrel you will have to remove these 2 helicoid keys. Be sure to mark one of them so that you know which one should go where when it’s time to reassemble your lens. If you accidentally jumbled them up then you might end up with a rough-focusing helicoid since these were broken-in to their own respective slot over a long period of use.

IMG_1333Remove the rubber grip and make sure not to tear it because it’s made of soft rubber and this one is thinner than most rubber grips from Nikon. Once the rubber grip is gone, you can now loosen the set screws holding the focusing ring to the outer helicoid.

IMG_1334This is the reason why I told you to mark where the infinity mark is situated, this whole thing is just being secured by 3 small set screws! If ever you fouled-up your focus, this is where you can adjust it so that your lens can focus all-the-way to infinity.

IMG_1336You can now safely separate the outer helicoid from the central helicoid but just be sure that you mark where they separate or you will have a hard time figuring out where they should mate. Please read my article on how to work with helicoids so you won’t get into a situation where you cannot put the lens back again properly because you didn’t have the experience with working with helicoids.

IMG_1337The inner helicoid also serves as the objective’s housing for this lens. Remove it like what you did before with the outer helicoid and make sure to note where they separated. This lens can be prone to the oily iris problem because the helicoid’s thread is so close to the iris. Make sure that you don’t apply too much grease here to prevent that from occuring.

Be careful when cleaning this part because you do not want to accidentally contaminate the insides of this assembly with dirty solvent or lighter fluid. The other parts of the iris assembly are also exposed (like the pins of the aperture blades) and you want to prevent them from being contaminated, too. Just clean it enough to get the old grease off from the helicoid. If you really need to clean it thoroughly in the case of a terrible fungus outbreak then you should dismantle this thing thoroughly to clean it.

Disassembly (Lens Elements):

Dismantling this lens to clean the lens elements is pretty straight-forward but you should be careful at handling the lens elements or you risk damaging them. You won’t need any special tools to access anything here apart from a rubber cup and a lens sucker. If you’re cheap, a lens sucker can be fabricated from a toy pistol’s bolts. On my lens, I didn’t have the need to clean the optics since it was still clean but if you need to clean yours then this lens won’t be too much trouble because it’s easy to service.

IMG_4851The front elements assembly can be separated from its casing by unscrewing it. To get to the front element you should use a rubber cup to unscrew its collar. Just be careful not to drop the front element to the floor and do this while everything is facing up!

IMG_4852A lens sucker is the safest tool to use to extract the front element.

IMG_4853The 3rd element is glued to its housing and it can be unscrewed. This casing also secures the 2nd element so be careful not to drop the 2nd element. Have everything facing down just like in this picture and you should be OK.

IMG_4854The bulbous 2nd element can now be safely removed using a lens sucker.

I forgot to take pictures on how to remove the rear elements! I’ll just elaborate on it here without using any pictures so I hope that you have a good imagination! I will update this in the future when I get the chance to open the rear elements again on another lens.

  1. Remove the retaining collar by unscrewing it. It may be sealed so place a small drop of alcohol at the seams to soften the lacquer.
  2. Use a lens sucker to remove the rear element, use a sharpie and make a small mark to remind you which side should be facing forward.
  3. There’s a metal shim in-between the rear element and the one in front of it, I would suggest using a a pair of tweezers to pick that out from the casing. The lens element isn’t symmetrical so please mark which way should be facing forward.
  4. The inner elements can now be accessed. Use a small lens sucker that will fit inside the diameter of the housing. Again, be careful not to drop anything.

This is still pretty basic compared to the more complicated designs. Just remove what is needed and leave the rest if you don’t need to clean them. If you need to remove fungus from your lens, read my article on how to remove lens fungus so you’ll know how I do it. Be careful when using chemicals and make sure that you don’t soak your lenses for too long or the chemicals will ruin your lens’ surface.


I liked working on this lens. It’s very simple (for me) and it should be a OK for somebody with a little bit of experience working with lenses to repair.  A beginner is better-off with a cheap lens from another brand to use as a practice lens. Get to learn the basics first and move-on to more complicated lenses like this one. An experienced repairman won’t find any challenge working with these. If your lens needs servicing and you do not have the proper tools then please send it to somebody who knows what they’re doing. The money you pay is worth it when you consider that you’re paying for somebody’s time, skill and health. Don’t be cheap, doing it yourself can sometimes make it more expensive!

IMG_1338You can re-assemble the lens by back-tracking all of the steps that you did but there are a few things that I would like to mention to make sure that you do it correctly.

Never apply too much grease because it may end up in your iris. A grease that’s a little on the stiff side works best for this lens because its focus throw is a bit shorter than usual. If you used a lighter grease then the lens may feel “cheap” because there’s no resistance.

When putting the focusing back, tighten the 3 set screws evenly. What you do is turn the screws at the same rate until they are all tightened properly. This is important because if you tightened them in an uneven fashion then the focusing ring will be a bit offset to one side and that will cause your focusing to feel uneven. Never over-tighten these, if you did then you may warp the focusing ring or strip the threads.

This lens was easy enough to service that you can overhaul it in under 2 hours provided that there’s nothing seriously wrong with it. While putting the lens back together, you’ll have to be careful about the focusing ring and where it should be positioned so that you can get precise focusing to infinity. Read my article on how to calibrate your lens’ focus to know how it’s done. Once you’re satisfied with how your lens focuses, don’t forget to add a thin strip of double-sided tape on the focusing ring just before you put the rubber grip back or else your rubber grip will slide when you turn the focusing ring.

When serviced properly, this little lens should provide you with many more years of fun. The lens itself is fragile compared to other Nikkors of the same vintage with the focusing ring as weakest part. You should not use too much force wirh the focusing ring since you can focus this lens with only a finger and this shouldn’t be a problem unless you abused this lens.

I hope that you have enjoyed this article and if you did, please do not forget to share this with your friends at social media. There are many people who did repair articles on this lens and the reviews are even more but I hope that mine is unique enough so people will still read it and see what I have to offer. See you guys next article, Ric.

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.

27 Comments (+add yours?)

  1. doc a
    Feb 19, 2016 @ 07:15:44

    Ang galing naman..salamat sa pag share uli..


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  3. Fadion
    Aug 06, 2016 @ 19:54:53

    I have a 50mm 1.8 AIS that had some fungus and a loose focus ring. It looked like an easy job, so I opened and cleaned the optics. Didn’t like the loose focus ring, so I disassembled the helicoids too. Unfortunately, I saw this article after I messed up. Didn’t mark the focus position and I have no idea how to realign. Any suggestion will be immensely useful.


    • richardhaw
      Aug 07, 2016 @ 03:55:56

      Hello, Fadioni! Unfortunately, you will have to find that out for yourself. You can check the other guides online and see where their helicoids lineup and try to guess it yourself. Ric.


  4. fadioni
    Aug 06, 2016 @ 19:55:33

    I have a 50mm 1.8 AIS that had some fungus and a loose focus ring. It looked like an easy job, so I opened and cleaned the optics. Didn’t like the loose focus ring, so I disassembled the helicoids too. Unfortunately, I saw this article after I messed up. Didn’t mark the focus position and I have no idea how to realign. Any suggestion will be immensely useful.


    • scott
      Oct 09, 2016 @ 11:12:32

      Ive made the same mistake not marking before separating helicoids. Driving me crazy, trying to find some footage of re assembly. There must be a method approach?


      • richardhaw
        Oct 10, 2016 @ 10:26:47

        Hi, Scott!

        Unfortunately, there isn’t. You rally have to mark where they separate. You could guess where they mate by rotating one of the helicoids the other way and hear a slight audible click. That click where the helicoid would mate. Looking at the thread also helps. If something like that happens to me, I would look at other people’s assembly notes to find some clues. Check my post on helicoids, it may have something. Ric.

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  6. Trackback: Internet Nikon Repair Resources – My Take on Photography and Diving (Underwater Photography Mostly)
  7. Carlos Fernandes
    Feb 19, 2017 @ 18:54:54


    Need some help, at least just to know if the following has even happened to you.
    I have followed your post and have disassembled a nikkor 50mm 1.8 e-series ( silver version) . It is a bit different from this post but allowed me to have a direction and the necessary advice.

    Anyway, I had a problem while putting the lens back together.
    I have stiff, very stiff focus. It is almost has the helicoidal don’t fit any more.
    It is if the plastique male helicoidal and the female aluminium do not fit any more.

    Has this even happened to you ?
    If so it there a solution ?

    Thanks for your help.
    Carlos – Portugal


    • richardhaw
      Feb 20, 2017 @ 05:37:19

      Hello, Carlos!

      I think I may have made a mistake there, I checked and the helicoids are indeed both made of metal, they only look like plastic so that tricked me.

      As for stiff focusing, be sure to check the helicoid keys and see if they are seated properly. Sometimes, they may not have been seated properly. What I do is before I tighten the screws of the helicoid keys, I focus the lens in and out to see if it’s OK and then I tighten the screws. Good luck, please message me when you have problems. Ric.


  8. Carlos Fernandes
    May 01, 2017 @ 16:17:14

    Hello Ric

    Thanks, You were right, I have taken the lens apart again, and very carefully followed your “instruction”. Its working very very well.

    I have a slight problem but I will ask on another thread.

    Thanks one again.



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  10. Chul
    Sep 20, 2017 @ 15:24:11

    Hello Richard,

    I’ve just acquired one of these lenses. It has two main faults: the corners are very soft up to f/2.8, and when you turn the focus ring back and forth, the image shifts slightly, I’m guessing due to a loose helicoid. Can you please advise, is there anything I can do to remove the slop in the helicoid? (I have not yet taken the lens apart.) And is there anything I can do about the corner softness?



    • richardhaw
      Sep 22, 2017 @ 01:22:36

      As you focus in and out, sometimes the framing would change. This is called focus breathing and is normal with many lenses.
      I am not sure about the corner sharpness. Very hard to tell unless I have the lens with me. Best thing to do is look for a similar lens and then try that. If that lens is OK then yours is probably not. Ric.


  11. chulerino
    Sep 20, 2017 @ 15:24:37

    Hello Richard,

    I’ve just acquired one of these lenses. It has two main faults: the corners are very soft up to f/2.8, and when you turn the focus ring back and forth, the image shifts slightly, I’m guessing due to a loose helicoid. Can you please advise, is there anything I can do to remove the slop in the helicoid? (I have not yet taken the lens apart.) And is there anything I can do about the corner softness?



  12. S. Staten
    Nov 18, 2017 @ 22:59:18

    Hi Richard, I just got this lens from Japan and it had a sticky focus ring. I disassembled and re greased the outer helicoid which fixed the problem, you tutorial was invaluable. Thank you so much. One thing you might want to add is that the outer helicoid separates without warning. I was ready to mark it for re-assembly but by the time I realized what had happened I was too late. I ended up trying each starting position methodically until I reached the right one… a long afternoon and evening. but the lens is so much smoother now. Thank you so much for these tutorials. I did the Micro Nikkor Auto 55 3.5 from your tutorial too. I looked for the Nikkor 85 1.8 H Auto from you but alas you don’t have this one. However I did find something in the end…. All the best. and many many thanks again for this valuable resource. Steve.


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  17. Dan Wharfe
    Apr 27, 2019 @ 11:13:04

    hi Richard i,ve got a 50 1.8 ai lens and unfortunately the set screw for front lens group has been stripped any ideas , many thanks


  18. brick and stone
    Jan 12, 2020 @ 01:28:34

    Excellent way of describing, and nice article to
    get data regarding my presentation focus, which i am
    going to convey in university.


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