Repair: NIkkor 135mm f/3.5 Ai

Hello everybody! I am now occupied with fixing Contax cameras for the coming series I am preparing for you. Contax rangefinders are very nice cameras and they are cheap if you compare them to Leicas and Nikons. They are cheap not because they are bad but it is all about market perception. If you want a very nice value today for old rangefinders then it’s hard to beat a Contax. They are better-built than most cameras of its era but it also lacked some important features which ultimately became the last nail in its coffin. Despite that, they are great cameras and they are very cheap now. Today, I will show you a lens that is also very cheap but performs admirably for every day use. Very much like the Contax rangefinder cameras, they offer great value for what you pay for and they’re also much simpler to service unlike the Contax which has a reputation for being difficult to service and very time-consuming so some repairers won’t even touch them. Read on.


The Nikkor 135mm f/3.5 Ai is the first major update of the excellent 135/3.5 lens family. It has remained almost unchanged optically since the Nikkor-Q.C 13.5cm f/3.5 RF debuted. While the optics were slightly tweaked over the decades that followed, the optical design remained largely unchanged despite the move from S-mount to F-mount until the lens in this article was introduced. The Nikkor 135mm f/3.5 Ai introduced a new optical design, it now has a 4 elements in 4 groups design and is no longer a Sonnar-type lens like all of its predecessors. I’m not sure what the benefits are because the older F-mount versions are all excellent like the Nikkor-Q 135mm f/3.5 Auto. This is a tough act to follow so I am sure that the upgrade had something significant to offer. Sonnar-type lenses have their quirks despite being great performers and focus-shift is one them to name a few so this may be one of those things that were fixed with this version.

IMG_1510The Nikkor 135mm f/3.5 Ai lens is a very handsome lens. I like it a lot because it’s a handy practical focal length for general photography. It’s also small and light so it doesn’t take a lot of space in the bag. The styling is also in-tune with the Ai lenses’ styling.

IMG_1511The glass is dirty but it’s in good shape. There are some fungus inside but it’s not that bad and the most important thing is the coatings are still OK. Good thing I got to this lens and I can prevent the fungi form growing even worse.

28275649_10155214106061911_1747990436_o.jpgThe lens is very well-built and feels very solid in my hands. It’s very well-balanced and it handles very well with whatever camera you mate it with. Here it is with the lens shade deployed, this is the first time this feature was implemented in this lens family. It’s a very handy feature and it makes the lens even more useful because you don’t have to bring a separate accessory with you. It’s also somewhat smaller then its predecessors which are all kind of long as far as small prime lenses go.

The Nikkor-Q 135mm f/3.5 Auto is already a very good lens to begin with and the earlier New-Nikkor version is just a cosmetic upgrade. The good news is this lens is just as good as the ones that preceded it. This lens family is characterized as being very performers even wide-open, has decent bokeh and relatively good flare resistance. Check my pictures to see what I mean.

HAW_1885I don’t really care much about these kinds of pictures but for people who care, this lens is typical for a telephoto lens as far as distortion goes. It has a mild pincushion-type profile, you can see it if you look very carefully at pictures like this but is insignificant when you use the lens in more practical applications. We’re not scientists and engineers here.

HAW_1904There are some purple and magenta fringing in this picture but you will really need to look very hard to see it. I recall that the older lenses suffer a bit from this so maybe this new optical design remedied this. Notice that this picture has a nice “3-D pop” to it.

(Click to enlarge)

The pictures above were shot from f/3.5, f/5.6 and f/8 respectively. As you can see, it is not a lens for bokeh lovers but it’s still has decent enough bokeh to satisfy you. The results at f/3.5 look very good. The picture is sharp where focused and the rendering is smooth and refined. The trade-off is you get some vignetting but that is unavoidable anyway. Stop it down to f/5.6 and you won’t see much difference but it does improve a bit when you look closer and the resolution is also a bit better. The bokeh balls also look polygonal now and it’s very typical of this lens to do this as it only has a 7-bladed iris. Stopping it down to f/8 will make the lens perform at its peak, although you really won’t notice much compared to f/5.6 because the lens is already very good wide-open. You gain resolution and DOF as you stop it down, the color fringing also goes away by f/5.6 and up. This all sounds boring but this is what the lens was calculated for. A lens that changes character as you stop it down is desirable artistically because the lens has more artistic potential than a lens that looks roughly the same in all f-stops. This lens has its uses and it certainly filled that very well and that is to cater to the lower-end of the market where people would buy it for the performance wide-open and wouldn’t care much for the balance and delicateness of the rendering. This overcorrection has became prevalent these days due to charts and all the pixel-peepes so the AF-S Nikkor 58mm f/1.4G had to be designed to bring this back. It was a very bold move by Nikon to introduce this lens at this age to remind people that charts and numbers aren’t everything in lens design, it is first and foremost an artistic tool and not something that’s made for engineers to test charts with. Well done, Sato Haruo-san. It is a very special lens for people who cherish the more refined characteristics of a lens. It was designed by him with this vision in his mind.

(Click to enlarge)

This lens is pretty good for candid shots. It can be hard to focus when using it for street photography because of the 35mm focal length and the f/3.5 maximum aperture is also not very helpful in acquiring focus. Notice that the lens has a very pleasing and natural character to its rendering, definitely a lens with that “classic look”. The portrait of that lady with the sunglasses was shot at f/8 and the lens is superb at this aperture. It is also a great lens for train-spotting for those who are into this kind of photography but it may be a bit too short since most people use longer lenses to shoot trains for safety.

That’s it for the introduction. I am sure that you will like this lens a lot if you use it. Why I prefer a larger aperture lens is because it helps me manual focus better due to the more shallow DOF, smoother bokeh and I get to have a lens that changes its rendering as I stop the lens down. Slower lenses usually won’t give this to me but I will sometimes bring this with me because I just want a compact and light setup and this is the reason why this is going to be part of my collection. Every lens has its place. Let’s now begin with the lens repair article!

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 now-growing 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 (Lens Barrel):

The lens barrel’s construction is pretty straight-forward but I will caution you about the glue that Nikon used on this lens. Nikkors made around the ’70s are notorious for this so I always approach them with caution and a lot of solvent. If a screw is stuck, just heat it or use acetone or alcohol to soften the bond first before attempting to remove it. I find this a bit surprising because for a lower-end Nikkor, this lens was very well-made and the parts  or construction reminds me more of the higher-end Nikkors of the same vintage. This is a nice lens for a beginner to work on provided he has the right tools for the job.

IMG_1512Locate a tiny grub screw near the front ring using this access hole on the hood. Not sure if yours has more than 1, I remember that mine only has 1 grub screw.

IMG_1513Now that the grub screw is gone, you can now remove the front ring. If it won’t come off easily, place a drop of alcohol along the seams of the front ring via the access hole. This is usually glued at the factory using lacquer and contact cement at times. I also suspect that repairmen are the ones using contact cement because that is overkill for this purpose.

IMG_1529The front ring can be further disassembled into these 2 parts. The name ring is screwed to the front ring and there are lots of dirt underneath it.

IMG_1514Once the front ring is gone, you can now remove the shade. There felt in the shade had to be replaced on mine. I used a very thin velvet for this, the material cannot be too thick or else the shade will be too tight.

IMG_1515These are the places where I found the grub screws. There is another one that you has to be removed before we can proceed, look for the grub screw that’s closer to the lens body and remove it. This is the one that is securing the front barrel.

IMG_1516The front barrel can now be safely unscrewed-off the lens barrel.

IMG_1517The objective can now be extracted. Since the front barrel is the one securing this thing, it is very important to never face the lens towards the floor or else this thing will fall to the ground and you will surely damage the glass so be careful.

IMG_1518Let’s now head to the other end of the lens barrel. Remove these screws so you can get to the inside of the lens barrel. If you are new to this, be sure to read my guide about how to deal with screws on the bayonet mount. Many people get stuck with this process because they used the wrong type of screwdrivers so here’s my article about screws and drivers.

IMG_1519The bayonet mount can now be safely removed.

IMG_1520The bayonet assembly can be further disassembled into these components. I had to clean my lens thoroughly so this had to be done. Be careful with the tiny screws on the bayonet mount because one of them is different. The screw at the 6 o’çlock position is the one that is preventing you from damaging your camera when you mount a lens to it so make sure that you don’t damage or lose it!

IMG_1521Before you can remove the aperture ring, you will have to remove these 2 screws.

IMG_1522Those 2 screws secure this aperture coupling fork. This is the mechanical linkage to the iris inside the objective.

IMG_1523The aperture ring can now be safely removed.

IMG_1524To remove the focusing ring you will have to first remove the rubber grip. Use a wooden toothpick or a small precision screwdriver and run it around the grip’s circumference to lift it from the glue. Be careful not to rip or tear this thing because these can be delicate.

IMG_1525The focusing ring can now be removed by unscrewing these screws but before doing that make sure that the lens barrel is set to infinity and do your best not to move it from that position. I always work on a lens while it’s focused all-the-way to infinity as reference. It is very useful so I will have a point of reference later during reassembly.

The upper lip of the focusing ring can be separated if I am not mistaken. I left it alone so I won’t have to remove it using a lot of force. These are usually glued with contact cement and it can be difficult to remove at times. Soaking this thing in an alcohol bath will help a lot to soften the cement. It’s not essential for you to remove it so just leave it alone.

IMG_1526The focusing ring can now be safely removed.

IMG_1527Assuming that your lens barrel is still at the infinity configuration, make some marks to remind you how things should align while everything is set to infinity. This will help you a lot later to determine if you reassembled your lens correctly or not.

IMG_1530The shiny grip and sleeve can be removed by extracting 3 screws at the lower part of the grip. These are sometimes stuck due to dried-up grease or glue, if yours is stuck just drop plenty of solvent like alcohol onto the seams to soften it up before you pull this out.

IMG_1532I took another picture of the lens barrel before I separate it into its bare components just so that I will have another reference picture for later.

IMG_1531The helicoids are being held-together by the helicoid key. The helicoid key is secured by these 3 screws, they can be hard to remove at times because they’re glued. Nikon used a tough epoxy-based thread lock during this era. If yours won’t come-off easily, heat these with a soldering iron or miniature torch and try unscrewing it while it’s very hot. I hate these screws because there are times when they would snap and I would require a screw extractor bit to remove what’s left in the holes so be careful and go at it slowly.

IMG_1533The helicoid key keeps the helicoids in-sync so when you turn the main helicoid, the two other ones will turn at the same rate. This will extend or retract the lens barrel and this is how your lens is focused.

IMG_1534Now that the helicoid key is out, you can separate the outer helicoid from the central one but don’t forget to mark where they separate because this is also where they should mate when you need to reassemble them later. Read my article on how to work with helicoids so you won’t get stuck later during reassembly.

IMG_1535Before you can separate the main and inner helicoids you will have to remove this metal guide. This prevents you from over-turning your focusing ring and sets your lens to only rotate within its focusing range, constraining it to its designed focusing range. There are a total of 3 screws if I recall it correctly.

IMG_1536Before removing it, make sure to mark which way should be facing forward to help you remember how to put it back properly later.

IMG_1537You can now also remove this brass ring. This brass ring is what the three screws on the focusing ring is screwed to. You can adjust how your lens focuses to infinity by adjusting the focusing ring later and this thing should also turn to allow you to do it.

IMG_1538You can finally remove the helicoid stop. It is hits the the guide that we removed a while ago and you can adjust it by tightening it with these screws. This is also important so that the lens will stop turning once it hits infinity. You will have to adjust this along with your focusing later after you reassembled your lens.

IMG_1539Separate the inner helicoid from the main one and never forget to mark where they part!

That’s all for the lens barrel. There seems to be more parts involved than usual but so far it’s still an easy lens to take-apart for an experienced repairman. Clean everything well, I also advise you to use a lighter type of grease for this because a stiffer one will just make this lens difficult to turn. Make sure that there are no traces of old grease on the helicoids and you will have to pick it with a toothpick if you have to. It’s tragic to find out that your helicoids are gritty after you have greased it and then you will have to clean it again. Just do it properly the first time and that will save you a lot of time.

Disassembly (Objective):

There is nothing special about the construction of the objective, its design is conventional and there’s nothing complicated about it. I didn’t clean the iris because mine is clean but if yours needs to be cleaned then I am sorry that I don’t have the information in this post. Please see my other articles to find clues on how to work on the iris if you have to.

IMG_1540The rear assembly can be separated from the main housing just like this.

IMG_1541And it can further be disassembled by removing this collar.

IMG_1550The rear element can be removed by removing this retention ring. Use a lens spanner to remove this ring. If your lens spanner can’t reach the slots then bend the tips outwards so the tips of the spanner can reach them.

IMG_1551The rear element can now be safely extracted with a lens sucker. Make sure to take note which side should be facing forward, putting a lens element back the wrong way can do damage to the lens when you reinstall the retention ring because the curvature will not match the housing’s inner lip.

IMG_1542The front elements assembly can be unscrewed from the objective’s housing just like this.

IMG_1543The front element is secured with a collar. Be careful not to drop this to the floor.

IMG_1544Extract the front element with a lens sucker.

IMG_1545the last element on the front assembly is sealed to its collar. It’s best not to remove this or if yours isn’t glued to it then be careful not to drop it. It’s sometimes held in place with a type of paint which is most likely enamel-based and it can be flimsy at best.

IMG_1546Remove this collar to reveal the retention ring of the inner element.

IMG_1547The retention ring can be removed by using a lens spanner. Notice that mine is wet with alcohol, it was secured with lacquer at the factory and alcohol with easily dissolve it.

IMG_1548Carefully remove the ring and make sure you don’t slip and damage the glass.

IMG_1549The 2nd element can now be extracted. This can be a tight fit at times so don’t force it.

All’s easy, right? The only thing I hated here is the amount of lacquer used to seal it. I am not a very patient man so I hate it when I have to wait for the alcohol to soften the bond before I work on something. When putting the elements back, make sure that they are all facing the right direction. The lens is simple enough with only 4 elements in it but you’re advised to take note of the orientation of all the elements just for good measure.


This lens took me more time than expected because of all the parts involved but it was a nice experience so far, a great project after a hard day’s work at the office. There are few things that can go wrong here so long as you took notes and references to aid you later in reassembly. Before you call it a day, there are still some things that you should do with it.

You must calibrate your lens so that it can focus properly at infinity. If you have not seen it, please read my guide on how to calibrate a lens for infinity focusing. The article has lots of information for you on how to do this for most Nikkors. Make sure you have rebuilt it properly before you attempt this or else all your efforts will go to waste so test it first and  see if everything is working as they should. This is usually the last step involved.

IMG_1555Reassemble your lens up to this point. Leave out the focusing ring and the hood for now.

IMG_1553Adjust your lens’ focusing range with this. Make sure that your focusing stops exactly at infinity. This is very important so your focusing scale will be as accurate as possible. See if you are satisfied with the results and then tighten these screws and apply a dab of nail polish to seal these 3 screws to prevent them from moving accidentally.

IMG_1556You can now reinstall the focusing ring. Make sure that the infinity sign is centered with the white line then tighten the screws to secure the focusing ring. I sometimes apply nail polish or thread lock to the threads of these screws to prevent them from moving.

IMG_1557The shade is bent and warped from damage. This is difficult to fix but we can get it back to being circular again with patience and some effort.

IMG_1563I have a circular cut of brass for this kind of problem, I use this as my anvil.

IMG_1564A rubber mallet is also handy for this kind of job.

IMG_1566After hammering it for some time, I got it to be as circular as I can. The tough part is the front edge of the hood because its lip is beveled. I do not want to hammer it too much or I will flatten the lip and make it even uglier than when I started doing this. At least it can now be positioned without effort unlike before where the ding is obstructing the shade’s path. I can live with this since I am not meticulous anyway. The lens is also clean now, it is now free from grime and fungi.

Thanks for reading along, did you enjoy this? I am currently exhausted but I had to rush this because I know people will be checking my blog tonight to see if I published a post. It is very important to me and I treat you and this blog with utmost importance so I cannot let you all down. I am currently involved with camera repair because I want to begin this new article of mine that I am preparing for you and for it to work properly I had to write a couple of things before I tackle the main topic. I always have my readers in mind so I’m spending extra effort and time just to make sure that you’ll understand what I am about to show you. It’s very important to put things in-context both historically and technically before I show something complicated because I am aware that the majority of you aren’t really into camera repair. See you guys next time, I am now preparing myself physically because I am about to cover 2 big events for you in the coming week, I need the stamina and time for it so wish me all the best. See you guys again next time, 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.

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Thank you very much for your continued support!


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.


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