Repair: Nikkor-P•C 10.5cm f/2.5

Hello, everybody! It’s Father’s Day today so I will greet all of the fathers who are reading my blog today a very happy Father’s Day! I was admitted to the hospital today because of my blood pressure but I am OK now but the most important thing is I spent time with my family. I spend lots of time at work and maintaining this blog that I often times find I am neglecting my family. Speaking of fathers, I am going to introduce you to a really special father in this article because this one started a long line of excellent lenses!


Today we’re going to talk about the father of this venerable lens family that we started discussing in the previous articles, the Nikkor-P•C 10.5cm f/2.5! It debuted late in 1953 to fill the gap between 85mm and 135mm. Some people find the focal length a bit odd but this made a lot of sense if you’re carrying a 50mm in your bag because 85mm just isn’t too different from 50mm and 135mm may be too long for many people. The f/2.5 maximum aperture may also be unusual for people who aren’t familiar with Nikon’s history, the f/2.5 maximum aperture was common and was also used on the W-Nikkor 3•5cm f/2.5. Back in the day, Nikon was in a contest with everyone so even a small lead counts (f/2.5 vs f/2.8) so this became the fastest lens in the 100mm class for some time.


This lens looks gorgeous with all those shiny chromed parts. You will sure to get plenty of stares when you shoot with this lens! I know some people who treat cameras as jewelry. I know it sounds strange but who am I to tell them otherwise? Focusing this lens can be a bit clumsy because of the long focus throw. You can also accidentally knock your focus off when you change the aperture and I find it annoying. Thankfully, I usually set my aperture before I focus my lens so this saves me a lot of trouble.

This was designed by the legendary Wakimoto Zenji, a giant in the Japanese optical industry and is the predecessor of the famous Nikkor-P 105mm f/2.5 series of lenses. The design was very long-lived and it pretty much stayed that way until the early 1970s when it was given an update by the disciple of Wakimoto Zenji.


Here is a simple comparison between the original 5-in-3 formula the later 5-in-4 formula. While the diagram shown to the left is for the Auto-Nikkor-P 105mm f/2.5 for the F-mount, the difference is negligible since only the rear element was modified by shaving-off 1mm just to make some clearance for the Nikon F’s reflex mirror so you can think of it as the same formula used on this lens. This is just for the sake of illustration to give you a better idea.

This design can be thought of as an enlarged Nikkor-P.C 8.5cm f/2, another lens designed by Wakimoto Zenji. The original design served like a template for this and it worked pretty well. I shoot with both lenses and I can say that the characteristics of both lenses are similar in many ways since both of the lenses shared the Sonnar pedigree.


This lens was sold as junk due to some coating damage by a previous fungus attack. I also noticed that it won’t focus all-the-way to infinity and the shop wasn’t aware of this. I love the beautiful engraved details on this lens which is very helpful. Minimum focus is around 1.2m which is adequate for a lens of this class.

This lens comes in 2 versions. The lens shown we have is the latter-type. It was just updated with a different way of attaching the lens shade where the original one has two small lugs to secure it and this one has none, resulting in a smoother front barrel that won’t snag on anything. The differences are insignificant, you can treat them as identical. There’s a Leica L39 version as well and the only difference is the lens mount.


Here it is compared to the F-mount version. They’re different in many ways but you can consider them to be similar because it is just a minor variation. Some people claim that the rangefinder version is better because the rear is closer to the film plane so artifacts like sphero-chromatic aberration, etc are near-absent compared to the F-mount version of this lens. I can confirm this myself and you can check my samples for reference.


Here it is with the rest of the gang. From the first one at the left from 1953 all the way to the last one to the right which ended production around the new millennium. If you’re a new Nikon photographer and you do not know what this lens family is about then I will advise you to read my articles and get to know these better. They are all excellent lenses.


It looks great with my Nikon S3. The 35mm, 50mm and 105mm is the trinity for the Nikon S3 because it has frame lines for these focal lengths, it’s really convenient. It’s heavy, it’s going to make your setup front-heavy so the best way to handle your setup is to hold it by the neck of the lens. You don’t want to let the lens dangle in front of your camera without support, this will wear the mount of the camera or damage the camera’s front casting.

Compared to other Nikkor telephoto lenses for rangefinder cameras, this is relatively new that it only came in the “new” scheme of chrome and black. Older telephoto lenses like the Nikkor-P.C 8.5cm f/2 and Nikkor-Q.C 13.5cm f/3.5 first came in all-chrome and then the two-tone “panda” version like we see here.

Let’s now examine how this lens performs. Knowing how a lens performs is key to using it properly. You should know its weaknesses so you can work around them and use all of the lens’ strengths to help you make a beautiful photo. The series of photos that I took in the section below were shot from f/2.5, f/4 and f/5.6 respectively. I omitted f/2.8 because it is too similar to f/2.5.

(Click to enlarge)

Vignetting can be terrible wide-open and it can reach to more than 2-stops-worth of light at the far corners. It gets much better by f/4 but only begins to disappear by f/5.6. It is really dark and is probably the biggest weakness of this lens. Now, this was designed as a general-purpose lens but it has great utility for portraiture so you can use this “flaw” to help give your portrait a unique look and help direct the eyes of your viewers closer to the center of the frame where you will most likely position your subject. The 2nd set will help illustrate how smooth the bokeh quality is, it’s one of the defining traits of this lens. Wide-open, the background melts into a smooth wash of colors, bokeh balls look nice and clean without any ugly outlines. The background remains smooth despite stopping the lens down but it gets less blurry due to the deeper depth-of-field. The bokeh balls still look circular because the iris isn’t angular, it plays a big role in the character of the bokeh. I consider this lens to have one of the best bokeh characteristics amongst all of the lenses that Nikon has made for the S-mount and “exquisite” is the only word that can describe that.

(Click to enlarge)

Here are some photos I took with the subjects at closer ranges. Sharpness and contrast at the center looks great wide-open and tonality look natural. Bokeh seems pretty smooth but you’ll see that it has the tendency to render some linear and long details at the background in a muddy way. It may just be just an unfortunate combo in the background of the 4th set because the bokeh looks gorgeous otherwise. Vignetting will make the corners look dark. People won’t notice it much as long as you do not have the sky or any solid-colored background. Like I said, you can use this to your advantage. I recall that people used to add this in the darkroom way into the 1980s. Resolution looks fine wide-open, stopping this down will make it better but not by a lot because it’s already good from f/2.5. There’s a really slight hint of chromatic aberration but you won’t see it unless you go out of your way to look for it. The field seems flatter-than-usual for a tele lens but I’m not sure about this, that’s just my impression. The technical quality of the pictures look great at f/5.6, it’s very sharp, clear and the contrast looks great. This is the aperture that you will want to use when sharpness and all those things matter most.

(Click to enlarge)

This renders great for subjects that are further into the scene. Longer lenses should perform better when shot at farther distances for obvious reasons. You’ll only see slight spherical aberration at really bright parts of the scene and that’s it. Again, vignetting will be your biggest concern here.

Let us see some real-life pictures, shooting mundane objects for tests won’t give you a good idea on how a lens performs. My reviews aren’t technical at all and I’ll always base everything on my impressions of the lens from real photos and experiences. The following photos were taken wide-open using my old Sony a7. I took these wide-open because that’s the best aperture to examine this lens’ character.

(Click to enlarge)

Please pardon me because these shots are a bit blurry since they’re all taken at slower speeds such as 1/60s because f/2.5 isn’t really fast-enough for this kind of pictures and my subjects are all moving. See how natural the photos look? They definitely have a vintage look to them. Despite being a bit blurry due to a shaky hand you will see that they’re sharp and if my subjects only stayed still then these would be better photos in the technical sense.


I love the mood of the pictures that I get with this lens, the rendering is very natural and the low elements count of just 5 helps achieve it. It’s not overly-corrected and all of its flaws work together beautifully to give you a unique-looking picture.


I love the colors that I get from it. The tones are subtle despite the contrast being a bit on the high side for a lens from this era, this is a good derivative of the Sonnar.

I also took some pictures using my Nikon Z6, it has IBIS and that helps a lot when shooting with a slower shutter speed.

Amazing details even near the edges at f/2.5! The bokeh quality is smooth, it is perfect for taking photos of people who are about 6m away from you. It’s a great lens for full-body portraits as the longer focal length will help make your model look a bit taller due to frame compression.

The colors that I get with this lens is wonderful even with fungus damage. It is never a boring lens, it’s a shame that Nikon never made one with AF and VR. I am sure that it will sell very well.

The bokeh quality is smooth in most cases but there are times when weird smearing happens at the blurred areas. This is just a combination of things so we ended with this. To be honest, this doesn’t look bad at all but I do not want people to think that this is a magic lens that doesn’t have any flaws or make my blog sound like it’s all-praises for Nikkors.

Sphero-chromatic aberration is well-controlled but there are times when it can show traces of it as evident in the worn parts of the track. This is simple to fix by stopping the iris down by a stop.

(Click to enlarge)

These are great photos for showing how good this is for real-world use. It’s a great lens for candid photos and stage photography but tracking subjects by-hand can be frustrating at times even with focus peaking but you will be rewarded with amazing photos if you nailed your focus.

Let’s now see some pictures that I took using film. It is important to see the performance of this lens when shot with film because this was calculated exclusively for use with it. It’s the only way we can see what the designers were thinking when they made this some 65 years ago.

(click to enlarge)

Here are some sample shots that I did as soon as I finished overhauling this lens. These have no creative value since I usually shoot a roll to test the lens and see if I got the focus coupled properly to the rangefinder and to see how this lens performs. See how smooth the bokeh is? You can also see that this is indeed sharp wide-open and it will improve a lot when you stop it down to f/4. You can also see that large polygonal blob when shot against the sun, this has more to do with its outdated coating than the design of the optics. A flaw set by the limitations of its time.

(click to enlarge)

Time for some color photos. The results are full of character as you can see in the transition from what’s in-focus to what’s not.

(Click to enlarge)

These 2 pictures were shot at around f/8 or so. At this aperture, it is capable of high resolution and sharpness across most of the frame. The colors look nice and neutral but a bit on the cool-side because this lens was calculated for monochrome film. The bokeh has a smooth character despite being shot at this aperture.


I shot this at around f/8 at 1/8s, dragging the shutter to give me nice motion blur. The corners look sharp as you can see from the cartoon girl’s eyes and the details on it. The tiny fishes also looks sharp. The contrast is just right, it is not too-high but it’s enough to not give you a flat picture.

(Click to enlarge)

Here are shots that I took wide-open. I think I shot these at around 1/60s or so. The lens is on the heavy-side due to the brass barrel, that added stability to my setup so I can use slower speeds than what I am comfortable with. A rangefinder camera is more stable because it doesn’t have a flapping mirror that shake your setup a bit.

So, do you think that you have enough information about this lens to make a conclusion? Well, let me help you with that. Buy this if you like this focal length and you like to shoot portraits, it is easy to adapt these now with all the available adapters so mounting it to a digital camera is not an issue. For Nikon rangefinder camera users, this is one of the key lenses that you have to own and it should never even occur to you if you should buy one or not. Leica shooters will also enjoy it but the focal length may be odd for Leicas, I will advise that you use an external finder when using these with Barnacks. For those rare instances when you would want to mount this to a Zeiss Ikon Contax, make sure you get one with “C” engraved on the barrel since those were calibrated for the Contax. This is a tele lens and accurate focusing is a must so get the right type for your system. It’s a lovely lens in both form and performance, you can get one for less than $250 or so if you’re lucky. These lenses stay relevant up to this day due to their utility, they are practical and simple that you can’t get any more basic than this. Unlike electronic lenses, these will still function well beyond our own lifetimes when taken cared of properly and this is one of the charms of using legacy lenses.

Before We Begin:

If this is your first attempt at repairing a lens then I suggest that you check my previous posts regarding screws & driversgrease and other things. Also read what I wrote about the tools that you’ll need to fix your Nikkors.

I suggest that you read these primers before you begin (for beginners):

Reading these primers should lessen the chance of ruining your lens if you are a novice. Before opening up any lens, always look for other people who have done so in Youtube or the internet. Information is scarce, vague and scattered (that is why I started this) but you can still find some information if you search carefully.

I highly recommend that you 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 and it will be beneficial for you to read this.

Disassembly (Focusing Unit):

First of all, we would like to separate the objective from the main barrel to protect it from any accidents. Some rangefinder lenses are very simple and so you can just remove the front assembly with your bare-hands. This lens was planned this way so you can change the main barrel to mount a Contax, Leica or even the rare F-mount version to it! Nikon sold the F-mount barrels as a separate unit, this is confirmed by old catalogs but the Contax and Leica fit were definitely sold from the factory as-is. Interesting, huh?


The objective can be easily removed by unscrewing it from the focusing unit. It may take some effort because it may be glued or old lubricant may have bonded it together.


Be careful not to damage or lose the brass shim. It’s used as a washer and to help adjust its focus. These are unique to each lens and were selected from a box of spares by the person who’s in-charge of calibrating its focus.


Remember I told you that this was sold as junk because it won’t focus all the way to infinity? This is the cause! I don’t know how this thing got inside but it was preventing the barrel from collapsing.


See, now it collapses all the way! I can really make a good living repairing lenses. Maybe I should do it in my retirement?


Remove the focusing ring by unscrewing these 3 screws that secure it to the inner helicoid.


Take note of the screws’ positions before you dismantle this further. Taking notes is essential but people just do not listen and message me when things go wrong.


This screw prevents the helicoids from turning outside of their focus range. Carefully remove it as this can be delicate because the neck of the screw is thin.


Take notes and photos before you dismantle. This shows the focusing cam’s inner mechanism. The screw slides within the slot as you turn the focusing ring. The cam on the other side pushes a lever in the camera that operates the rangefinder.


This is how much the barrel will extend before the screw is removed. I took this so I’ll know later if I re-assembled this correctly.


Separate the helicoids and never forget to mark where these parted. If you forgot to do this you will spend plenty of time guessing where these should mate later since you will have to mate them in the same position as where they separated. If you are new to this, read my guide on how to work with helicoids to prevent any mistakes.


The sleeve can be removed after extracting its 3 screws. I believe that this is overkill since the scale can be engraved into the main barrel. I always find oil underneath this so maybe this was implemented to somehow help with keeping oil from seeping out of the barrel and this is not merely a cosmetic part.


Let’s go to the rear this time. Remove this set screw so you can remove the retainer ring. It is there to secure the ring from accidentally being moved.


This retention ring can be un-screwed by using a lens spanner. Remember to rotate it exactly to how it was before you remove it so you can put the set screw back.


Once the ring is gone you can take out the focusing cam mechanism.


To remove the cam’s collar, unscrew this carefully and be sure not to lose it. This screw is used to keep the cam in-place and to keep everything together.


Once the screw is gone, everything comes apart. That spring is responsible for pushing it out so it comes into contact with the rangefinder lever all the time.


You can remove the collar on the mount if you wish but this won’t help with repairing this lens except from removing dirt trapped underneath it.


This is how it comes off. Again, there is no real benefit to removing this.


If your lens does not sit properly to the mount on the body then you can use your hands or a pair of pliers wrapped in rubber to bend these a bit. This is a delicate operation and I’ll advise you not to do this unless you know what you’re doing because the problem may not be on the lens but on the flanges on the camera’s mount itself.

I doubt that many people will have problems with the main barrel but there will be people who’ll want to take it apart due to grease migration or a dry helicoid or worse, a seized helicoid. I make it a habit to do this for all of my lenses because I just do not trust what’s there and I do intend to keep these things working forever.

The helicoids have been thoroughly cleaned. I brushed them with a stiff pig-hair wheel brush on a Dremel then wiped them until the tissue wipes clear of anything. I’m very meticulous when it comes to this step because I do not want the old grease to contaminate the new one. Use a lighter type of grease for this because the internal helicoid on the camera will add resistance and they will all add-up. Don’t apply too much grease or you will end up with an oily lens.

The cam at the rear and the spring under it were lightly lubricated with the same grease used on the helicoids. This will help prevent it from squeaking. If you found rust on the spring, clean it off using a fine steel wool or WD-40 and be sure to clean it thoroughly and leave no residue before lubricating it lightly and putting it back to its assembly.

Be careful with the Dremel. Only use a soft organic brush to polish anything related to the threads in your helicoids. A steady hand is required.

Disassembly (Front Barrel):

The objective is easy for me since I work with this lens family regularly. It is so simple and the elements are of a comfortable size to handle so handling them is easier. There is nothing I’ll need to warn you about, just follow the fundamentals, take lots of notes and be careful.


The front elements cell can be removed by unscrewing it. This neatly comes off as an assembly as you can see here. Be careful not to scratch the back as it is exposed and can come in contact with anything inside the casing.


The front element can be removed by un-screwing the front. This may fall all the way to the ground if you’re not careful so do this while this is facing up.


The front element can now be extracted using a lens sucker.


The 2nd group consisting of the 2nd, 3rd and 4th elements (a triplet) comes off when you unscrew its collar. Both ends are accessible without removing it from its housing so you can clean it just like this unless there is fungus or serious “schneideritis” which rarely happens with this lens.


I am removing this just in case somebody is curious. These are usually tight so don’t not force it or you will risk damaging the glass.


The rear element can be accessed and cleaned thoroughly by removing this collar. You may have to place a drop of alcohol to soften the seal that Nikon applied to these to secure them.


You can extract it by using a lens sucker. At this point I will place a dot with a Sharpie to identify which side should be facing the front. The curvature of this element is a bit shallow and it can be difficult to distinguish which side is convex. I have worked on this lens family long enough to know that this is concave on the surface that’s facing the camera. Do this as a precaution, a simple permanent marker works well.

People who just want to remove fungus or dirt will only take it apart up to this point. If you are hardcore, continue to the next section.

Disassembly (Iris Mechanism):

The iris assembly on rangefinder lenses aren’t as delicate as the ones found on automatic lenses (SLR’s mostly) so having a bit of oil in them is tolerable but never acceptable. I will clean this one just to show you how if it bothers you. The oil will evaporate eventually and it will settle on the surface of the elements and ruin the coating. Of course, this is bad but it is your call if you want to spend this much effort on cleaning the iris assembly. Better having an oily iris then having one named “Humpty-dumpty” since you can’t put it back together again.


Extract this screw but mark the position of the aperture ring first.


The aperture ring is being held by 3 small set screws. See the dimple on the collar in the picture? That’s where the screws sink into. You have to put this ring back together again the same way as how it was so the mark we made in the previous step will help a lot.


Extract the brass ring to remove the rotator cup that’s securing the iris. You may need a sharp pick and it may take you some time to get it out.


This screw couples the rotator cup to the aperture ring, remove it to extract the cup inside of the housing.


Carefully remove the cup with your fingers.


The collar can be removed by unscrewing it. Do note the original position of this thing before you remove it. Some people count how many turns it takes to unscrew it but I use measurements instead.


See how intricate the iris is? They are more difficult than the ones found on most SLR lenses because there are more of them and they are inter-locking with each other. The good thing is they are usually heavier so they stay will put. If you want to know more about these things, read my article oh how to repair preset-type irises.


Drop the blades into a soft and clean lens tissue and be careful not to warp them. The iris blades are very delicate and a damaged one will result in an irregular-shaped iris or worse, an iris that doesn’t close or open properly.


Carefully wipe the iris blades with a lint-free tissue such as a lens tissue and use naphtha to dissolve the lubricant. This one is easy since the blades don’t look symmetrical. The trick is to have the pin on the rounder end connect to the hole on the housing. The rounder end makes a clearance for it to pivot. Putting it back the wrong way will result in an iris that won’t work properly. You will know it when you see it.


There are many techniques to do this, mine is to slide a blade under the one on top and then push it into place by using a pair of tweezers. Only handle the pins and never the blades.


Sorry for the mis-focus. I’m sure that you can see that the iris mechanism is now properly re-assembled.

The only troublesome part is the iris and I doubt many people will even try to attempt taking it apart but if ever you have the need to then this is how to properly do it. Some people will simply saturate the iris with naphtha or solvents and wipe-off the gunk but that isn’t the proper way to do it and the problem will soon come back. I’ll admit that I also do it sometimes on very rare occasions where I can’t open the iris because it’s stuck or some butcher glued the parts so nobody can open it up again. It’s best to leave it like that than to subject the lens to repair trauma.

I hope that you got yours back together after this. Don’t worry, it will take a few attempts before you learn how to do this. If you really want to practice how to do this then do it on a cheap Russian lens sold for parts. No need to ruin a good lens just for the sake of learning a new skill. Nikkors are family heirlooms.


As far as lenses for the Nikon rangefinder system goes, this is bog-standard, it has a lot in common with other telephoto lenses in terms of engineering so I was not even worried about this thing when I worked on mine. In fact, this took me less time to overhaul than expected because there aren’t many parts to take care of. I am saying this from the position of an experienced hobbyist.


This one comes in metric. I sold this but I wish I did not because its rarer. I rarely sell my lenses and if I do, I usually sell them to people I know. I may buy it back one day.

I would not advise that you ruin one as an experiment because these aren’t cheap like the majority of the F-mount lenses due to their rarity and age so only attempt repairing this if you’re an experienced repairer. Send this to a reputable repairer if you don’t have the tools or experience to repair this.

I hope that you liked this one, if you benefitted from this, do not be shy and donate to my cause. I’m considering updating this account again and it will be very helpful if you can help me with the upkeep so I can keep this thing running and keep the files on another server to help with the bandwidth because my blog is obviously very picture-heavy. Thank you guys again, 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 site’s upkeep, you can make a small donation to my ( 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’s name or other information so that the donations will totally be anonymous. This is a labor of love and I intend to keep it that way for as long as I can. Ric.

11 Comments (+add yours?)

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  3. Trackback: Repair: Preset Iris Reassembly | Richard Haw's Nikon Maintenance Site
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