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Repair: Micro-Nikkor 55mm f/2.8 Ai-S

 Hello, everybody! It has been a long busy week again for me and I really apologize for not posting in a timely manner. I was busy with work and family as usual and since spring is just around the corner, I am down most of the time due to hay fever. In fact I am currently very dizzy as I am typing this so please bear with me if I have typographic or grammatical mistakes. Time flies very fast and my baby is going to be 1 year old soon and this blog is on it’s 1st quarter now. I hope that I can maintain this blog as long as I can and I am happy for the support that you are giving me.

I am again pleased by my growing readership and some of the new readers request that I do a post regarding the Micro-Nikkor 55mm f/2.8 Ai-S. This amazing lens has a reputation for the tendency to have oily aperture blades so it ends up being in the most requested list. This lens can be complicated so this post will be longer than the usual so please bear with me as I try to break this down as easy as I can for beginners to service this lens.

There is also a request that I make the pictures bigger for people who read this on a smart device or simply for people with bad eyesight like me. With that being said, from now on I will post bigger pictures on this blog. I am very thankful for feedback like this so please do not hesitate to tell me my writing in the comments section.

Introduction:

IMG_2326.JPGThe 55mm Micro-Nikkors have a long pedigree starting with the first one made in 1961. I have an affinity with this lens since I shoot candid street portraits everyday and bugs,too when they are in season. I also occasionally get the request to do product photography and 55mm is just OK for that, giving me a more natural perspective as opposed to the 105mm that I also use. Longer focal lengths can make the subject look flat and most of the time you do not want that in your product photography.

The 55mm family has evolved throughout the decades that it has been in production with the latest one being the subject of our tear down. I would also like to note that the last lens in the line, the AF-Nikkor 55mm f/2.8 has the exact same optics as the subject of this post (Micro-Nikkor 55mm f/2.8 Ai-S).

IMG_1061The lens is small and balanced really well on many Nikon cameras. The relatively fast f/2.8 maximum aperture also makes this lens a very good choice for everyday photography with the added bonus of being able to achieve 1:2 magnification. The 55mm focal length is also nice for candid street photography and portraiture (on DX).

IMG_2327Here in this picture you can see how much this thing extends to achieve 1:2 magnification. In order to achieve life-size (1:1) magnification, you will need an extension tube (PK). This PK extension tube is packaged and sold along with this lens when brand new but is usually lost or just simply not included when you buy this lens.

This lens is so good that it is rumored that some companies actually use this for industrial purposes. The sharpness and flatness of field of this lens is superb for industrial use that even NASA has a special version built for them to bring into outer space. It is also worth mentioning that this lens is still currently in production and you can even buy this brand new from stores around the world. The longevity of this lens alone is a testimony to such a masterpiece of optical engineering .

Weaknesses:

We can generally assume that manual focus Nikkors are pretty tough and can handle a lot of abuse in the field and this lens is no exception. All the lenses produced by anybody has their own weakness and for this particular one, the CRC unit (it’s main selling point) is it’s weakness because there is one more thing that can fail in the lens when abused or used for a long time.

One of the most famous issues with this lens is the problem of grease migration. The CRC unit is actually a part of the objective (lens assembly) and it is positioned very close to the iris assembly. Nikon initially used a light and runny grease for this lens and over time the grease would slowly creep into the iris assembly resulting in oily aperture blades. This can be avoided by properly storing the lens but it happens all too often because of the design so Nikon decided to use a thicker and more viscous type of grease to negate this problem on later production lenses.

The second most common problem for this lens is ceased helicoids. The CRC unit’s tiny helicoids’ grease get gummed up and will prevent you from focusing your lens. This is a pain to fix since a full overhaul of the helicoids is in order.

With these issues in mind, let us begin dismantling the lens itself so you can see how and why these things fail.

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 (Initial):

This is one of those lenses that can only be opened through the bayonet plate. If you have been following this blog, most of the lenses that I have featured here can be opened up by simply removing the optical block (objective) from the front barrel. This lens is different as you will see later.

This lens can be broken down into several parts:

  1. Focusing unit/main lens body
  2. CRC unit
  3. Objective/lens assembly
  4. Iris assembly

I will outline this tear down in a similar fashion to make it more manageable and easier to read or else it will be a long and jumbled mess. You can choose to start in any order as in the case of repairing the iris assembly only and leaving the helicoid overhaul for another day or situation.

Let’s start!

IMG_1516Carefully remove the 3 screws securing the bayonet mount to the lens. You can now safely remove the bayonet mount and store it for the mean time.


IMG_1518To remove the objective (optical assembly), remove these 3 screws. Be sure that the lens is focused to infinity when you do this and avoid turning the focus ring because this will be your reference point.


IMG_1520Now, carefully remove the objective and make sure that you do not knock or turn any part of the assembly. This lens has CRC and it is a precise fit so you would want to know where things are exactly aligned and by how much. Do step this while keeping the lens focused to infinity.

WARNING:
The objective can be heavy and it may drop and dive into the floor if you are not careful so always be aware of this!!!

Disassembly (Close Range Correction or CRC Unit):

IMG_1538As you can see from this picture, I have marked all of the important alignments when this is focused to infinity. This includes the helicoid stop for the CRC unit (encircled) and the midline of the lens. Also notice the gaps and remember them for reference.


IMG_1539Remove these 3 screws to separate the iris assembly from the rest of the objective. One of the screws might be obscured by a lever just like in the picture above so you may need to turn the lever to access it. Note that the 3 screws are gone in the picture. Just take a look at that fungus, Yuck!


IMG_1540Carefully separate the iris assembly from the objective and be sure to keep things aligned while doing this. You may have marked them in the previous steps but you just want to be careful because CRC can be a pain to re-align later. Just take a look at all that dirt!


IMG_1541.JPGNow, to separate the CRC components you have to first unscrew these and remove the key to split the tiny CRC helicoids.


IMG_1542Now, separate the CRC helicoids and be careful to mark where they separate. These lens is my own property so it’s OK to mark it like this but if this thing belongs to somebody else then you would want to make your marks smaller.


IMG_1543Next, remove the main CRC helicoid from the rest of the objective. Be sure to note where that notch on the brass ring should be before you remove it. You can also remove the brass ring to thoroughly clean it but mark where things should be aligned as this is the part that maintains the CRC unit in sync with the rest of the objective.

Disassembly (Objective or Optical Assembly):

IMG_1544First, remove this part using a rubber plug to reveal the 3 little screws underneath it.


IMG_1545Now, unscrew these to remove the “hood”. Be careful not to scratch the front element!


IMG_1546It should come off easily. If they have put any adhesives on this part then you should put a drop of acetone to soften it up and attempt it again after a few minutes.


IMG_1547Yuck! Just take a look at that fungus under the front element! By the way, I kept the screws there for safekeeping so please ignore the fact that they are there on this picture.


IMG_1549.JPGUse a lens spanner to remove the front elements assembly from it’s helicoid. I also had to apply some acetone on this part since it was glued in place by some kind of thread-locking liquid (that red lacquer looking thing).


IMG_1550.JPGThe front elements assembly can be taken apart by removing the retention ring that holds everything together. Carefully use a lens spanner to open this thing up and do not force your way when it is being glued in place as you might damage the front element.


IMG_1552The rear elements assembly (attach to the iris assembly) can easily be removed by twisting it with your hand. It can be further taken apart by removing the retention ring that secures the rear element by using a lens spanner. That thing to the right of the iris assembly is the front elements assembly.


IMG_1557Six elements in five groups, simplicity is best. The 2 retention rings are placed above for reference. You should mark the sides of each element assembly with a soft lead pencil so that you know which one faces forward when you reassemble you lens.

To get rid of the fungus, I cleaned it with 1 part ammonia, 1 part hydrogen peroxide. Wipe it with alcohol and cleaned with microfibre cloth and blower. As for really stubborn fungus types, you need to soak the lens element in the ammonia/hydrogen peroxide solution for an hour or so to soften it up before you can wipe it off the glass element. Do not do this for lenses that were glued together because this might eat away the balsam that was used to bind the glass together.

Disassembly (Lens Body or Focusing Unit):

IMG_1521First, I got rid of these 2 screws that secures the aperture ring to the aperture fork. Once the screws are gone you can safely remove the aperture ring.


IMG_1525The aperture fork can now be safely removed from the lens.


IMG_1524Next, to separate the helicoids, you have to first remove the helicoid key by removing the 3 screws that secure it to the lens chassis.


IMG_1526You can now safely remove the helicoid key from the lens body.


IMG_1527Now that the helicoid key is gone, you are free to separate the main helicoid from the rest of the lens. Be sure to remember where it separates. Mine separated at this point. If you decided to remove the focusing ring before doing this then you should mark where they separate by scribing a fine line on the surface of the helicoid where it will not be seen or get in contact with another helicoid.


IMG_1529Carefully remove the rubber grip by sliding a small and thin screwdriver underneath it and run the screwdriver on the whole circumference of the rubber grip to free it from whatever adhesive Nikon has applied. Be very careful not to puncture a hole on the rubber grip while doing this.


IMG_1530Once the rubber grip is gone, you can now unscrew the front part of the focusing ring and keep it in a safe place. You do not want to warp this part because if you did you will end up with a rough focusing lens as this part will rub against the front barrel when you focus.

You can also remove this part while the rubber grip is still attached if the rubber grip itself is not being held by any adhesives. This is preferable since you do not risk the rubber grip tearing itself while you remove it with a small screwdriver so attempt to remove this first while the rubber grip is still attached.


IMG_1531There are three screws in the focusing ring that hold it to the main helicoid. These screws are also responsible for adjusting your lens’ infinity focus so you would want to remember where they are originally before you remove them by marking their respective positions. If you messed up, you can simply adjust it later on (discussed in the Post Mortem section).

The group of 3 small screws circled in the picture is used to secure and adjust the helicoid stop. You can usually overhaul your lens while leaving these alone. These are positioned precisely so that your lens can achieve infinity focus so leave these alone if you can help it.


IMG_1533You are now free to remove the focusing ring from the main helicoid.


IMG_1534This is the best time to remove the inner helicoid from the main central helicoid. Be sure to mark where these separate.


IMG_1536For a thorough cleaning job, remove the chrome grip by unscrewing 3 small screws. With the chrome grip gone, you can now remove the outer sleeve (with “Made in Japan” mark) by carefully twisting it with a grippy rubber glove. Nikon usually glue these metal sleeves to the main barrel with some kind of lacquer or glue so please be patient and put acetone in between the seams if the sleeve will not come of the first time around and repeat it until the glue is soft enough and attempt to twist it off again. I advise cleaning this since grease usually finds it’s way under this metal sleeve.

Post Mortem:

When lubricating your helicoids, be sure to use a light general purpose grease because is you use a stiff grease all the resistance from the CRC unit’s helicoids and the lens’ main focusing helicoids will all add up resulting in a lens that takes a considerable amount of torque to focus. This will hasten the wear on the bayonet mount and the focusing ring and as you can see from the steps prior, the focusing ring is just being secured by 3 small M1.7 screws.

For many people, the reason why they would want to read this tear down is because they need to clean up the oily aperture blades on this lens. This is a common problem for the Micro-Nikkor 55mm f/2.8 Ai-S lens but is easily preventable (Which I will describe later). Many people will just open up this lens to access the iris assembly to clean it and then put the clean iris assembly back into the lens and assume that it will work again without any problems. While this is fine for most cases, you would want to clean the root cause of the problem which is the oily helicoids so it is highly advisable to just do a full overhaul of the mechanical components of the lens.

I did not need to clean the aperture blades on all of the Micro-Nikkor 55mm f/2.8 Ai-S that I have fixed so far, so I did not take any notes. It is not difficult to do at all but if you need to clean yours then just head to this YouTube video from the master himself and see how he overhauled the iris assembly.

IMG_1551Be sure to apply a little nail polish to both ends of the spring to secure it. A small amount goes a long way so do not put too much.


IMG_1554To adjust your lens when it fails to achieve infinity focus, reassemble your lens but leave out the frontal parts so you can still adjust these screws on the focusing ring until you can achieve infinity focus. Once you got it right then you can finish reassembling your lens.

Finally, do not forget to lightly lubricate the slots and canals of the helicoid keys for both the main one and for the CRC unit. If you forgot to do this then you might end up with a squeaky lens. Do not over lubricate this or you will end up with oily aperture blades again. A little goes a long way as far as lubrication is concerned.

Conclusion:

This is a very fun lens to work with. I would not consider it to be as easy task because of the CRC unit but with proper guidance and tools a beginner will be able to overhaul this lens properly without any trouble at all. I have not clocked myself on how much time it took me to overhaul this but all I can say is that it will probably take you more than half a day’s work, maybe even a whole day if you consider overhauling everything including the ball bearings on the bayonet mount.

Once overhauled, this lens will last you many many years of use since manual focus lenses are built so tough compared to what is being produced these days and if you have used the right lubricant and not put too much of it then the aperture will never get oily again. Just remember to always store this lens facing up and set to f/5.6 or f/8 so that the aperture will not get stuck wide open or fully stopped down. I am not sure what kind of metal they use for these but they do get rusty if you do not use them often.

I hope that you have enjoyed this post. It was rather long and it took me around 3 nights to write this since the lens is a bit complicated. If you have benefited,enjoyed or learned from this post then please do not forget to share or click on the ads on this page. This will help me a lot in terms of maintaining this blog and keeping this alive for everybody to enjoy. Thank you very much, 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 paypal.com account (richardHaw888@gmail.com). 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.

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24 Comments (+add yours?)

  1. Ron V.
    Feb 23, 2016 @ 20:21:12

    Again…………….excellent work Rick, much appreciated.
    These lenses are well known for having helicoid issues………….mainly the grease solidifying over time.
    This article has given me the encouragement I needed to pull my sample apart.

    Reply

    • richardhaw
      Feb 24, 2016 @ 02:54:21

      Thanks! this is not difficult to be honest. a 55mm is probably one of the first lenses that i took apart. (1st one was a Sigma super 24mm from the 80s). I am thinking of adding some exotic lenses like the GN and the 5.5cm f/3.5 here because their engineering is just so different from what you usually see from Nikon!

      Reply

  2. Angel
    May 10, 2016 @ 14:00:56

    Excellent guide Rick. I just bought a cheap 55/2.8 with stuck iris so im about to follow your guide.
    Thanks!

    Reply

  3. richardhaw
    May 28, 2016 @ 14:07:31

    Hello, Angel!
    Sorry for the late reply. The aperture not closing may be a sign of oil in the aperture blades. I do not understand what you mean by the DOF pin.

    Reply

    • Angel
      May 28, 2016 @ 19:12:35

      I meant the aperture lever but later i found that its normal on some versions. Today i tested it and this lens is wonderful!

      Reply

      • richardhaw
        May 29, 2016 @ 00:07:47

        Hello, Angel.
        I am not sure about that, it should spring back all the time when the lens is assembled. the lens is amazingly sharp. it is also very useful as a normal lens. Ric.

  4. dfgriff57
    Aug 09, 2016 @ 16:51:58

    Hi Richard, I went through you’re procedure and all is well but for one tiny thing that I can’t figure out. I removed the rear lens elements for cleaning but upon assembly, it looks as though the two elements touch each other when I tightened the outer retention ring. I didn’t notice this at first so it could have already been like this. Are there any shims or other spacers in the rear lens group besides the one you show? Thanks again for making tutorial, helped a bunch

    Reply

    • richardhaw
      Aug 10, 2016 @ 00:35:24

      Hi! Sorry but I do not remember that part of the lens very well. Are you sure that what you heard is the apex of the lens coming in contact with each other? Or is it just the sides. be careful as you might break the glass. Ric.

      Reply

      • dfgriff57
        Aug 10, 2016 @ 00:49:58

        Hi Ric thanks, yes it is making contact. I can see a sort of spot forming right in the middle as I tighten the retention ring. If I leave the ring slightly loose, the center of the lens remains clear and the images I make are sharp. If I tighten the ring hand tight, the spit appears and images have a fuzzy look in the center. Guess I can save it as a paper weight. Thanks again.

        Don

      • richardhaw
        Aug 11, 2016 @ 13:58:30

        Hi, sorry for the late reply. I am quite busy these days. You have to be careful as you may have the rear elements in the wrong order/direction. I am not sure but this is a very common mistake. Ric.

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  6. Chris_R
    Jan 06, 2017 @ 11:38:50

    Great article, thanks. Do you have a recommendation for lube for the outer main focus helicoid? I have a couple which have gone stiff (105 the same).
    I’d better buy a screw extractor kit – insurance!

    Reply

    • richardhaw
      Jan 14, 2017 @ 14:06:21

      Hello, Chris! Sorry for the late reply. I tend to use the same grease for the whole lens to avoid mixing the grease’s chemistry and foul up the helicoids as time goes by. I use a thin type of grease sparingly to prevent the grease from migrating into the iris. Ric.

      Reply

  7. Trackback: Repair: Micro-Nikkor 105mm f/2.8 Ai-S | Richard Haw's Classic Nikkor Maintenance Site

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