Repair: Nikkor-O 35mm f/2

It is beginning to be cold now here in Tokyo, so much so that sitting on the wooden floor of my workshop makes my butt numb after a few minutes and we are still at the early weeks of Autumn! The sun now sets at around 4:30PM and it gets dark around 5:00PM so taking pictures in the dark is now becoming one of my primary considerations as far as making a decision as to which lens I should bring for the day and this brings us to today’s subject!


Today’s subject is the amazing Nikkor-O 35mm f/2 lens! This lens was introduced in 1966, it was Nikon’s fastest wide lens for a few years until the even faster Nikkor-N 35mm f/1.4 lens was introduced in 1970. Not only was this lens fast at f/2, the minimum focus distance is also very short at just 0.35m. This allows for really close focusing and combine it with the shallow depth-of-field that an f/2 lens would give you wide-open and you can get creative with this lens.

img_2052The Nikkor-O 35mm f/2 is rather big for a Nikkor prime but not so big as make everything look and feel unbalanced. It is common knowledge that this lens was rather difficult to manufacture for it’s time because it is a bit complicated but this design stood the test of time and the optical formula stayed for quite some time until the advent of the AF model lens, that says a lot!

The performance of the lens is very good, even wide-open! Vignetting and falloff are not much of an issue and rather low, the contrast is very high and sharpness is excellent even at f/2. Many even compare this lens to it’s more expensive Leica rivals that costs multiple time more. The only real complaint I am hearing from other people is that this lens flares really bad but from my experience the flare is quite natural and compliments the resulting image somewhat. This is subjective so I will just leave it there.

(Click to enlarge)

The images above were mostly shot wide-open. Check out the picture of the dog with the wig and see how sharp this lens can be wide-open. This lens has a very neutral feel to it and the images it produces are very natural and amiable. It is sharp where it’s focused and the sharpness falls off rather naturally and blends into the rest of the frame. Can you see those attributes in my sample pictures? I can say that this is a good walk-around lens for everyday carry specially if you like to take portraits of people on the street then the fast maximum aperture is also helpful when it starts to get dark. The focus throw is just right for me and not short like the later Ai-S lenses.

img_2119Here it is on my Nikon F, it balances really well on older film bodies despite the size. It is a bit larger then your usual Nikkor prime of the same era like the Nikkor-H 28mm f/3.5 or the Nikkor-S 35mm f/2.8 lenses. I have always wanted to own one to be honest but the price of this thing never goes down due to it’s popularity and utility specially with filmmakers. I was lucky to find one in the junk section of my favourite camera shop for a nice price but the inner elements were terrible and the lens was full of fungus and mould. That problem with the inner elements seems to be common with this lens for some reason, check the end of the article to see what’s wrong.

I also own the Nikkor 35mm f/1.4 Ai-S lens and all variants of the 35mm f/2.8 lenses from Nikon. Between those lenses and this, I would almost always pick this, any of the 35mm f/2.8’s and lastly the Nikkor 35mm f/1.4 Ai-S. My reason for doing so is the handling plus the f/2 maximum aperture is just right for my style of candid street portraiture.

OK, this looks enough for an introduction so let us now begin with the teardown!

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.

Dismantling (Separating the Objective):

Following best practices and common sense, we will separate the objective from the lens barrel before working on the rest of the lens barrel. This will prevent any accidents from occurring to the precious glass elements.

We usually only mention this in passing but not for this lens. The Nikkor-O 35mm f/2 was a difficult lens to produce for it’s time and part of it is it’s construction. Usual Nikkor primes of the same era have simpler ways of securing the objective to the lens barrel but this one will require us to take apart more things in order to achieve the same thing.

img_2072In order to remove the objective, we need to remove the focusing ring first. There are 3 of these screws that you should get rid of. They are sealed with paint so be careful when you unscrew them so you will not strip the head.

img_2074Be sure that the lens is focused all the lens is focused all the way out to infinity when you removed the focusing ring and then mark where the infinity mark should be on the surface of the central helicoid. This will serve as your guide later when you reassemble your lens.

img_2075The reason for removing the focusing ring is to access this little set screw. This one is kind of long and may be sealed with clear lacquer. Take it off or simple loosen it enough so that you can unscrew the front barrel off.

img_2076The front barrel is connected to the objective so if you pull the front barrel off the objective comes off with it. This is unusual for this type of Nikkor prime and is more reminiscent of the Nikkor-H 28mm f/3.5’s construction.

img_2077Look at the front part carefully and you will observe that there are 2 sets of slotted rings in there. What you want to do is get a lens spanner and fit it to the outer ring and unscrew it. The inner ring is used to secure the front element so leave that alone for now.

img_2078You can now separate the front elements group. You may be confused as to why we’re now buggering with the objective since all we want to do is separate the objective from the lens barrel to keep it safe while we work on it. Look at the next step to see why…

img_2079The front ring is sandwiched between the front elements assembly and the casing of the objective! Who would’ve thought of that? Would you? It took me some time to figure this out for myself.

img_2081That’s a lot of work just to get the front ring off, don’t you think? Now, reinstall the front elements assembly to the objective and keep it safe for now.

Disassembly (Main Barrel):

Now that the objective is safely stored out of the way, we can now begin with the fun part! The lens barrel’s construction is very typical of Nikkor primes made in the same era, there is nothing noteworthy at all. You will spend the most time with the objective for this lens.

Beginners would want to follow each step precisely to avoid making any mistakes. Special care has to be taken when documenting where the helicoids separate. If you are new to the trade, be sure to read my article tackling the topic of helicoids.

img_2082Remove these 5 screws from the bayonet plate to remove it. Observe how the screws are a bit scarred, this indicates that the lens has been opened before. Be careful when removing these screws as they may be sealed with Loctite. If they will not come off easily then place a drop of acetone or two into each screw and give it some time for it to work before you try to attempt anything on these again.

img_2083The bayonet plate comes off without any effort at all. See the white stuff on the holes for the bayonet screws? That’s either dried-up grease or Loctite residue.

img_2084Before you remove the aperture ring, be sure to unscrew this one first. This screw serves as a pin to couple the aperture ring to a mechanism inside that is connected to the iris.

img_2085You can now safely remove the aperture ring from the lens. If you try to remove this before you got rid of the screw in the previous step then you will surely damage something inside the lens.

img_2086Next, we need to remove the shiny aluminium grip from the lens. Remove these screws so you can pull the grip off from the lens, there are 3 of these in total. Be careful not to scar the the beautifully machined fluted pattern on the grip!

img_2087And off it goes!!! Just look at that dirt that was accumulated all these years, yuck…

img_2088In order to separate the helicoids, you will need to remove the helicoid key first. Look for 2 circular holes on the lens barrel and use these to access the screws of the helicoid key. Use the correct-sized screwdriver for these because they are easily stripped. I remember that mine was already slightly stripped indicating that the person who opened this prior had a bad time with these. For safety’s sake, I replaced these screws with good ones from one of my spares.

img_2089Here is the helicoid key. You may need to loosen the helicoids a bit to get this off. Observe this picture and you will see that the helicoid key is mounted in reverse, keep this in mind.

img_2090Separate the outer and central helicoid and be sure to mark where they separate! Failure to do so will result in a terrible time for you later when you reassemble your lens as you guess where these should mate.

img_2091In order to separate the central and inner helicoids, you will have to remove this helicoid stop first. This constrain the helicoid’s rotation to correspond to the focusing ring’s scale. This is in the way so get rid of these 2 screws to remove this part.

img_2092This part is glued in place most of the time and can be hard to remove. I would sometimes use a screwdriver to wedge the underside of this part just get it off.

img_2093You can now separate the inner and central helicoids now that nothing is in the way. The circled part is what’s getting in contact with the helicoid stop. You can remove either one, I always just prefer to remove the bigger part most of the time because they are less likely to be ruined.

img_2094It’s now time to strip the parts to it’s bare components. Remove this brass ring by using a small screwdriver as a pick. This can get annoying so please be patient.

img_2095With the brass retention ring gone, you are now free to remove the aperture fork. This fork is connected to a ring and this part is in charge of coupling the aperture ring to the iris.

Disassembly (Objective 1/2):

As I mentioned previously, you will spend most of your time working on the objective of this lens. I have even made the unusual decision of splitting this section into 2 parts so the reader will not get confused.

The objective is pretty easy to take apart but you will have to be careful because a lot of the parts have been glued by the factory. Since this lens has 2 cemented groups, you will want to be careful with the solvents and acetone. These chemicals will dissolve the cement used on these if you are not careful.

Part 1 involves working on the front part of the objective while part 2 is about the rear part of the lens. I hope this makes sense to you. I will also skip the iris assembly since my lens has a properly working iris so taking that apart doesn’t make any sense.

img_2096This should look familiar to you. Separate the front elements assembly from the housing of the objective. Notice the holes that I encircled? Place a small drop of acetone or alcohol into these and wait for it to work on the adhesive. It is also a good idea to do this the first time you open the lens.

img_2097Twist this brass ring until it comes off.

img_2098The brass ring secures this doublet in place. Mine was a little stiff so be careful pulling this thing off or you might damage it. A doublet is basically 2 glass elements cemented together to form a single unit.

img_2102Next, remove this plate by using a spanner on these 2 depressions.

img_2103Once the plate is off, use the spanner again and remove this part. Be careful not to scratch the glass!

img_2104The 3rd element is housed in the ring that you previously removed. It is glued in place and forget about removing this from the housing. It’s not worth it.

img_2105Now, back to the front. Remove this screw carefully. Sorry for the focus.

img_2106The screw holds this ring in place, simply unscrew it from the front element group’s case.

img_2107Be very careful with this step or you will end up with an expensive paperweight. With this facing down, unscrew this ring and be sure not to drop the front element to the floor!!!

img_2108The front element isn’t glued in place and you can easily remove it from the ring.

Disassembly (Objective 2/2):

The rear part of the objective is not as complicated as the front assembly. It could be if we will talk about the iris but since my iris assembly is working perfectly, I will just skip it.

img_2099The protector for the rear element can be easily unscrewed with your fingers.

img_2100The rear element is glued in place in it’s housing so do not bother to do anything to it. You can unscrew this off easily with your bare hands.

img_2101Lastly, use a spanner to remove this part housing the inner elements.


This was written by request so I hope that our friend will benefit from this when he takes his lens apart. It’s not a difficult lens to work with if you know how and where to open the parts. With this guide, you will skip much of the guesswork and prevent anything awkward from happening to your Nikkor. Even with that caveat, I would rank this lens as perfect for the advance beginner.

I probably spent 2 nights working on this thing, one night for the main barrel and another for objective. I hate working with objectives since you have to be clean and precise. All that dust blowing and wiping is too repetitive and tedious that I would rather work with all that grease on the helicoids. I am sure that somebody else on this planet enjoy doing this and to him, I give you a toast!

img_2109Here are the elements in their proper order, 8 elements in 6 groups. The 3rd from the top row is made up of 2 elements as well as the 1st one on the 2nd row (from the left).

img_2111The inner element has started to degrade, showing ugly signs of “Schideritis” and cement separation on some of the edges of the doublet. Both will not affect the image quality of the pictures taken with this lens but really severe cases will probably have an effect, specially with cement separation. This topic will tackled in a separate blog post, I am contemplating about making one for the next post. If you remember what I mentioned in the introduction to this article, I mentioned that these problems seem to be common with this lens so be on the look out for this when shopping for this lens. Look a good and careful look at the inner elements and look for any white or silver edging near the middle of the lens as if it has some sort of cataract and if you see it, be sure to ask for a discount or just skip it.

Thank you very much for patronising my blog. I hope that my blog has become part of your routine and hobby. I am very happy to receive messages from people encouraging me and asking for help because I like talking to like-minded people. It reminds me of my old scale modelling club days where people just sit together and learn from each other, that is until some annoying people join the club and spoil everything. Oops, I will end it here before we go too far with the off-topic subject.

Keep your self warm, I will not be opening lenses and fixing cameras much these coming months as the wooden floor is getting too cold for my butt. Yes, I sit on the floor working in my stuff. This is common here in Japan. Enjoy the beautiful autumn colours, 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.


10 Comments (+add yours?)

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  4. Jon
    Nov 24, 2017 @ 02:25:17

    Really interesting Ric!
    I’m trying to remove the three screws around the bayonet. I’ll by a vessel screwdriver but what is the specific size I need for those screws?


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