Repair: RF-Nikkor-P.C 8.5cm f/2

Hello, everybody! It is Nikon’s 100th anniversary today! The company was founded with the merger of several smaller companies and it was called Nippon Kogaku which means Japan Optical literally. There are milestones throughout Nikon’s 100 years of continuous operation and I will tackle some of them here in my blog. You may have already seen my Nikon Museum series which I began a few months ago along with the related articles and this is just a part of that. I hope that you will enjoy this series, Nikon lover or not.


Today, I am going to show you a historically significant lens as far as the Japanese optics industry is concerned and it is no other than the venerable RF-Nikkor-P.C 8.5cm f/2 lens! The RF-Nikkor-P.C 8.5cm f/2 was perfected and sold in the post-war reconstruction years following WW2. It was heavily inspired by the Zeiss designs since Nikon was new to this game and needed somewhere to start from. I would consider this lens to belong to the 1st generation wherein the lenses have very strong resemblances to the Zeiss “inspirations”. By the 2nd generation, Nikon had learned enough and the lenses began to look different in terms of design and engineering. Everybody has to start somewhere, right?

IMG_4508.JPGThis is a compact but very dense lens. The RF-Nikkor-P.C 8.5cm f/2 is a joy to hold in your hands. It was made of chrome-over-brass with big pieces of glass, hence the weight. This lens is legendary and you can even say that it was partly responsible for introducing the Japanese camera and optics industry to the world. Nikon is known here (in Japan) as one of the companies that helped revive the Japanese post-war export industry and this lens helped it achieve that and I will make a separate article about that in the coming weeks.

IMG_4507.JPGThis is the lens with the hood on. The cap is rare and is used on earlier type of this lens. It came with the set and that cap alone can cost $60 just by itself. The earlier versions don’t have a filter thread for you to attach a hood so it had to be secured by friction alone. The light meter is a VC2 meter by the way. It is the best meter for classic rangefinders and it’s still being sold new. It is very accurate and compact. It’s money well-spent if you ask me.

IMG_4537.JPGOne very annoying thing about this lens is that the focusing ring moves when you rotate the aperture ring. You should hold the focusing ring firm before you rotate the aperture ring so that your focus won’t change. This is not exclusive to this lens as a matter of fact, many lenses from this era and earlier were made like this. If you are wondering why the engraved characters and numbers look so good despite the lens’ age, I will tell you that I repainted them with enamel paint. Read my article on how I repaint these things on my old blog post on this link. This is important because the chrome finish can make the feint lettering harder to read. The fact that they were thin and tiny doesn’t help at all.


The optical design is simple and it is just another variant of the Zeiss Sonnar. There are 5 elements in 3 groups as you can see from the illustration above. If you think that this is a familiar design then you may be correct because this design is also the basis for the very popular RF-Nikkor-P.C 10.5cm f/2.5 lens. Both render similarly and this is the reason why.

IMG_4538Here it is beside my lunch of raw fish and rice. It balances very well on the Nikon SP and the 8.5cm frame lines of the Nikon SP is very useful for framing. There are 2 variants for this lens. One is the chrome-over-brass finish that you see here and another is the rarer black anodized aluminium alloy version. There are several minor variations in between these 2 major variants such as the early ones having a click-less aperture ring and some versions having a different minimum aperture and so on.


(click to enlarge)

Check out the pictures above. All of them were shot wide-open at f/2 I think. This should give you a good impression of how this lens performs wide-open where it counts. Look at the lovely “bokeh” and see how sharp the subjects are despite the ancient coatings used. I had a hood when I shot these and that helped a lot! However, when the sun is situated at the periphery of the frame just outside of what’s in view you might get a big blob on your frame. I counter this by shading the lens with my palm. I also shot a variety of backdrops ranging from geometric shapes like architecture to organic ones like foliage. Foliage is a very tool for showing how good a lens’ bokeh is because they are sort of reflective and is multi-faceted as individual leaves act like little waxy mirrors. As you can see from all the images above, it doesn’t seem to exhibit the dreaded “二線ボケー” or “double-bokeh”. This is highly desirable for a lens like this. On the down-side, it did seem that this lens is prone to produce some smudging of the bokeh. It is not terrible at all and you may not even see that on everyday scenarios so don’t worry, just enjoy the many strengths of this lens!

The pictures above shows how this lens perform in real-world scenarios. Too bad that we don’t have a model here because this lens is perfect for portraiture! All of the pictures in this article were shot with a 24MP full-frame camera and some images were cropped and had their exposures tweaked a bit by around a stop. I know that the contrast looks great but I promise you that I didn’t mess around with the saturation or anything else. The lens is considered by many to be the best in its class during its time, now you know why.

I generally do not shoot tests but I wanted to show you how organic-looking the images from this lens look. Do note that all images were shot hand-held and framing or focus is not exact so please take these into account and be kind to me.


(click to enlarge)

The series of sample pictures above show how the lens performs as it was stopped-down from f/2, f/2.8, f/4 and f/5.6 (from left to right). The lens is already pretty sharp wide-open and it improves significantly when stopped down to f/2.8. By f/4, what’s not in focus still looks creamy but the subject’s contrast improved a bit. Finally, the lens looks like it is at it’s peak when shot at f/5.6 but you loose the creaminess of the background. What’s good is that the background still retains its organic look and doesn’t look hard at all. The good thing about the 10-bladed curved iris of this lens is that your aperture will still be round even if you stop it down. Most rangefinder lenses are like this and this is one advantage of the rangefinder system over the mostly-polygonal irises found on almost all automatic iris lenses found on SLR’s and modern mirrorless systems (?).

DSC00195I’m not a cat person (I don’t like them) but I do appreciate a good cat picture if I saw one. The picture shows just how delicate the lens is when shot wide-open. It’s sharp where it’s in focus and the transition to what’s not in focus is very smooth. The image also has good separation, giving you that classic “Zeiss-pop” as what some people call it these days. It is just a fancy way of saying that the image looks three-dimensional instead of flat. Also see how rich the colours are when there aren’t any strong light sources within the frame. Old coatings just don’t compare to the new ones that were introduced just a decade after.

That’s it for the introduction! I hope I succeeded in showing you what this lens is capable of so we are going to commence to the teardown! This is what you are here for anyway!

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 (Focusing Unit):

If you’ve been following my blog for some time then you’ll know that I prefer to remove the objective from the focusing unit first if possible. This will prevent any accidents from happening to the objective and its glass. The “safety first” advice applies to everything.

You will need to have several slotted screwdrivers available because the screws come in many different sizes and you should use the correct driver that will fit the slot precisely. If the driver is too big, you will want to file it to fit. The screws here are very prominent. I always try to be very careful with them because ruining the heads of the screws is going to affect your lens cosmetically in a very big way. Yes, aesthetics are important for lenses like this where the screws are part of the design. Think of it like the chrome trims in cars.

You will also need a proper lens spanner for this. If you do not have one then do not even think about doing this! Buy the best one you can afford because quality matters here.

IMG_4509The objective can be screwed off from the focusing unit. This is very typical of the earlier Nikkor telephoto designs for rangefinders. If yours is stuck then don’t force it and drop a small amount of naphtha or pure isopropyl alcohol into the seams to help dissolve what’s in there. Make sure that you do not put too much or it will get into the iris assembly.

IMG_4510The screw near the top edge of this picture is responsible for keeping the focusing ring or the helicoids of this lens from going beyond its focusing range. You can remove it now or you may opt to do that later before you separate the helicoids. It’s your call.

IMG_4511While the focusing unit is set to infinity, I got a caliper and measure the clearance just so I will know if I got things right later on. Pardon the cheap plastic caliper, the digital one is safely stored somewhere. It is expensive so I take good care of it.

IMG_4512Take as many pictures and notes before you begin removing anything. Here is the rear of the focusing unit with the rangefinder coupling cam/collar. This is how it should look like when you put it back together. Better take notes now than regret not having them later!

IMG_4513Let’s begin taking apart this things. Begin by removing the retainer ring that secures the rangefinder coupling mechanism. The retainer ring is being secured by 2 set screws and here is one of them. Use the proper screwdriver that will fit the slot or you’ll ruin it!

IMG_4514Here is the other one. Notice that the screws look different. I am not sure if it came out of the factory like that or it has been modified by a repairman but whatever the case is, you should take note of small details like this to prevent you from making any mistakes later.

IMG_4515The retainer ring can now be safely removed with the help of a lens spanner. I am going to caution you about this part. It was precisely secured into place so that the rangefinder coupling mechanism won’t wobble if it’s too loose or squeak when it was too tight. Count how many times you have to turn it to get it off, that is one good way to remember how it was put together before you remove it. Take note of the 2 small screw holes and how the 2 of them aren’t identical at all so remember to put the right screw back to the right hole!

IMG_4516The whole mechanism can now be removed. Do not worry about its orientation, this part is free-turning and the most important thing is to put the screw you see here into its slot found on the inner surface of the focusing unit and that this thing sits flat on it’s ring.

IMG_4517The cam/collar can be removed by unscrewing this off.

IMG_4518Here it is stripped down to its basic components. The spring ensures that collar is always in contact with the rangefinder in the camera. Take special care to note how this spring was seated on the screw that we removed a step ago. If you got it wrong then you will get frustrated and open this thing again just to guess how it was originally.

IMG_4519Time to separate the helicoids! I turned the focusing ring until I got to this point wherein I am not able to collapse it further and then I took note where the red infinity mark is. In this picture, the mark ended up on the 2nd “e” of the word “feet”. If I mate the helicoids again later, I should be able to get to this mark again when I turn the focusing ring all the way in. Taking small notes like this will save you from hours of frustration later.

IMG_4520The most important not to make is where the helicoid separated because this is also the same spot where you should put them back together. Mind separated here with the mark for infinity landing in between the 15ft and 20ft mark.

IMG_4521Removing the 3 screws securing the focusing ring will allow you to remove it from the its helicoid. You can opt to remove this earlier but I decided to leave this thing intact until I was done taking all of my notes because the characters on the focusing ring are great for taking notes. Never forget to mark the orientation of the focusing ring before you take it off because it has to be on the right orientation when you secure it back later. If you did not do this then all of the characters will all be on the wrong places and your notes will all be for nothing. This is how many people get frustrated and send their lenses in to the repairman in the hopes that he’ll fix it but without any notes then he’ll be also clueless!

IMG_4522This decorative sleeve with the scale can be removed after unscrewing the 3 screws that are securing it. You’ll usually find plenty of oil underneath this so clean that mess up!

That’s it for the focusing unit. I cleaned off all of the old grease with plenty of naphtha or naphtha. Make sure that there are no traces of the old lubricant there and scrub it with an old toothbrush. I even soaked my parts in denatured alcohol just in case and gave it a good rubbing with Scotch-Brite. This will ensure that the old lubricant won’t contaminate the fresh grease. I use a lite grease for the helicoids because the helicoid on the camera is coupled to this and turning both helicoids on the camera and the lens at the same time is going to give you just the right damping sensation. I hope you get what I meant!

The rangefinder coupling mechanism was also lubricated using the same grease that was used on the helicoids. Every part that has metal-to-metal contact was lightly lubricated. I would like to emphasis that the part where this mechanism connects to the main barrel has to be lubricated properly because if you left it dry, then the focusing will not feel just as good as it used to be. This is issue amplified when you mount the lens to the camera.

Disassembly (Objective):

The objective is pretty basic when you compare it to the W-Nikkors which have elaborate designs just to keep the lens small. Many of the parts can be unscrewed with your hands alone none of the parts were glued as far as I can recall. The only thing that I will have to warn you about is to be careful with the glass. They are heavy and they can roll off from the edge of your table or you can drop one directly to the floor! Again, safety first!

IMG_4523The front elements assembly can easily be screwed off from the objective with your bare hands. There may be a thin brass shim around the collar so be careful not to damage it.

IMG_4524The front ring can be unscrewed from the front elements assembly’s housing. Be careful not to scratch anything at this point as everything is exposed. You can remove the front element by unscrewing the retainer ring that secures it. You can actually see that ring in the picture above. Use a proper lens spanner for this and be careful not to scratch your glass! It may be a tight fit so apply constant pressure or soften it up with some alcohol.

The 2nd group consists of the 2nd, 3rd and 4th elements and are cemented together into a single group called a triplet. This is very typical of the Sonnar design.

IMG_4525The casing for the rear element can be unscrewed just like this.

Store the glass somewhere safe while you work with the rest of the lens. Place them on a soft surface like a clean towel to prevent them from being scratched. Sure, the coating on Nikon’s lenses are tougher than what the Germans used but that doesn’t mean that it’s OK for you to just leave them on any surface! Do not wipe the triplet with solvents or expose it to high head or the cement will deteriorate and this will become an expensive repair.

Disassembly (Iris Assembly):

The iris assembly is probably the most intricate thing on this lens but it is still simple. I’m used to this kind of work so it was peanuts for me.

IMG_4526The aperture ring can be removed after you got rid of the 3 screws holding it. I made it a point to mark where the original position of the screw hole is in relation to the casing. If you for got to do this then you will end up guessing this thing’s orientation.

IMG_4528Next, unscrew this big screw off so you can remove the collar. Notice that there are some marks on the collar. These are preexisting ones made by somebody else. This means that this lens has been serviced at least once in its almost 70 years of existence.

IMG_4529The collar can now be removed once the screw is gone. Again, make a small mark so that you will know how to put this back together later. Some people use a marker for this but I would rather be safe so I scratch it gently. I will sand this later to make it less obvious.

IMG_4530Here is the iris! It is acceptable for rangefinder lenses to have a little bit of oil in their iris but having this much is not good. The ideal scenario would be a bone-dry iris but that is not always avoidable given the age of these things. Oil on the iris will evaporate and end up sticking to the inner surface of the lens elements and this’ll result in a hazy element.

IMG_4531This cup can now be safely removed with your fingers. I should have warned you earlier that by removing the screw and its collar, this cup is now loose so be careful not to drop it! Work with the objective with it facing the ceiling to prevent any accidents.

IMG_4532Just look at that thing. I will drop the iris leaves on a  soft surface to prevent it from being damaged. These are tougher than the cantilever designs but you just have to be sure.

IMG_4533Just take a look at that. It was so oily that it came of as one single unit! Here is an article on how to work with preset-type irises and there are videos there. Check the link out for more information; the lens shown there is different to this one but it is still relevant.

Clean each individual part (of the housing) carefully with naphtha to dissolve any old or hardened gunk in there. Wipe it clean with a lint-free tissue so you will not end up with fibers on your lenses. I always take extra time and care in cleaning the housing’s parts so I am assured that nothing will settle on the glass as I use the lens or else I will have to do another round of cleaning! Better to spend some time doing this than do the while thing again! Putting everything back together can be a challenge for beginners but don’t worry.


This is routine for me and since I have worked on a couple of RF-Nikkor-P.C 10.5cm f/2.5 a few months ago, there was nothing that caught me by surprise because the construction and designs of both lenses are similar in many ways. Would I let a novice fix one as their first lens? Never. Nikon rangefinder lenses are not as common or cheap. A Russian lens is a better choice for this purpose. The Russian lenses are cheap and those sold as junk are even cheaper so you won’t be guilty if you have ruined one for the sake of learning.

The lens is pretty straight-forward and the only thing that took me some time was the iris but that didn’t take me a lot of effort to do and I will show you how in the next steps.

IMG_4534Here are the individual iris leaves after cleaning them thoroughly with naphtha. Wiping them with a soft lint-free ensures that all that gunk is removed. Be careful with these and make sure that you don’t warp or bend any of these. These are irreplaceable!

IMG_4535Putting them back can be very challenging to beginners but I am used to this. My style is to put them back individually and then leave out the last 2 or 3 for later because they are supposed to be interleaved with each other and the best way for me to install them is to slide one end under the other blades and push them into place using a pair of tweezers. I always handle them with their pins to prevent damaging the leaves themselves. This will require plenty of patience and you may even end up doing several attempts. That is OK.

IMG_4536Here is the gorgeous iris after it has been overhauled! The iris is always round whatever you do and the corners aren’t really obvious so you will never end up with polygonal and irregularly-shaped bokeh balls. This is the original bokeh machine of Nikon!

Here we are again at the end of another article. Did you enjoy this? This is only a part of my Nikon Centenary series and I intend to show you more historically significant Nikon gears in the coming weeks so come back and see what I have published! Thank you and please share this blog to your friends if you find my work interesting or beneficial to you. My site relies on “ad impressions” so each time somebody sees an ad in my page, my blog gets a fraction of a cent in revenue. Thanks again and see you next week, 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.


6 Comments (+add yours?)

  1. Trackback: Articles Index | Richard Haw's Classic Nikkor Maintenance Site
  2. Trackback: Repair: Nikon 100mm f/2.8E | Richard Haw's Classic Nikkor Maintenance Site
  3. Trackback: Repair: Preset Iris Reassembly | Richard Haw's Nikon Maintenance Site
  4. Trackback: Repair: W-Nikkor 3.5cm f/1.8 | Richard Haw's Nikon Maintenance Site
  5. Trackback: Repair: New-Nikkor 85mm f/1.8 | Richard Haw's Nikon Maintenance Site
  6. Trackback: Repair: Nikkor-S.C 5cm f/1.4 | Richard Haw's Classic Nikon Repair and Review

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