Repair: Nikkor-Q 20cm f/4

Happy new year, my friends! 2016 has been a crazy year for a lot of people, for me it was a stressful year because my beautiful assistant is working off-site so I have to do the job of 2 people at the studio. It was also a year wherein we lost the likes of Bowie, George Michael and other important ’80s pop icons. This made me feel old because I grew up listening to New Wave and other ’80s pop and rock. Thankfully, just like the loud electronic rhythms of yesteryears there is one thing that is slowly getting a revival – Classic Nikkors. Amongst these Classic Nikkors is something that I consider somewhat to be a hidden gem when it came to the cost/performance ratio – the Nikkor 20cm f/4!


This lens is part of a very historical lens family and is the lens that is succeeded by the lens that we talked about in this blog post. Although there are many similarities between this and the Nikkor-Q 200mm f/4 lens, the Nikkor-Q 20cm f/4 is made very differently. There are numerous differences in the lens barrel’s engineering that you can consider this barrel design to be totally different.

img_2868Here is my collection of Nikon’s 200 f/4 primes. All of them were bought as junks and were restored during my spare time. These comprise all of the major cosmetic variants for this lens line and we will have a guide for each of these one of these days.

From left to right (chronological) you have:

  1. Nikkor-Q 20cm f/4 bis – This looks similar to it’s successor but there are a few small differences between the 2 in terms of construction. The latter lens was made more to be more durable and short cuts in production are also made to manufacture this lens faster/cheaper without compromising quality.
  2. Nikkor-Q 20cm f/4 – The subject of our blog post. While nothing much has changed from the previous version, there are numerous improvements made in productions to cut corners and also to make the lens more durable. Note that it’s slightly slimmer than it’s predecessor so parts are NOT interchangeable in most cases.
  3. Nikkor-Q 200mm f/4 – This is the last version of the Nikkor-Q range. The minimum focusing distance has been lessened to 2m, the handling and construction was vastly improved, the optics were tweaked a bit to offer better sharpness and the C version is probably the sharpest in this range because it uses Nikon’s multilayered coating. We have a guide for this lens and I advise that you also read it, here’s the link.
  4. Nikkor 200mm f/4K/Ai – This version/s represent a total departure from the older lens range because the optics are totally different. The lens is also smaller and lighter, for many people this change alone is a big deal when deciding which lens goes in the bag or stays in the dry box. The K (New-Nikkor) and Ai versions are near identical so I have bunched them together in one group. I also made a guide for this lens, click on this.
  5. Nikkor 200mm f/4 Ai-S – This is the last version in this long series. Optically, it is the same as the previous one above but the construction is totally different. The coatings are probably different on the later ones but I have no data for this. Handling is pretty much the same as the previous version and cost-cutting decisions are obvious in the construction, very typical of Ai-S lenses (scotch tape,anyone?).

While the optical formula largely remained unchanged between this lens and it’s successor, the minimum focusing distance and sharpness has been vastly improved on the later lens. This lens still has the 3m minimum focusing distance which limits it’s use considerably so you are mostly confined to just using this lens on mid-ranged subjects or things that are far away up to infinity. In actual use, this isn’t so much of a crippling factor since you are going to want to shoot subjects in that range anyway when you use a tele lens.

img_1663Here it is with an M-ring, some people like to use this as a macro lens. It’s such a beautiful lens with all that chrome and aluminium accent, don’t you think?

I would consider this lens for daytime outdoor sports and for shooting wildlife that will be still enough for you to capture since there is no AF on this lens. It has limited use for street photography but the compression a 200mm lens gives you is sometimes useful to get the framing that you desire. Many people also value this lens for macro photography as a relay lens. Some would even add extension rings to this to get closer to their subjects, I tried and it was challenging for outdoor macro work because of the lack of AF and the slightest wind breeze would throw everything out of frame. I am not the person who shoots flowers and mushrooms so what do I know? But I will assure you that I saw stunning pictures from this lens used in the manner I described above.

(Click to enlarge, all shot with the Nikon Df)

The image above is tiled randomly but just look for the sunstar photos. As you can see, the simple 4-element design (hence, Nikkor-Q for quad) doesn’t produce a lot of ghosts unlike zoom lenses with many elements like the Zoom-Nikkor 43-86mm f/3.5 lens, this lens will only give you 1 big ugly blob when shot into the sun. At f/11 it is still diffused somewhat but at f/22, the blob “solidifies” and you get a nice sunstar.

Looking at the picture of the ducks you can see that the lens is great wide-open but CA is kinda high for my taste, this is typical for vintage lenses with lower element counts and it wasn’t really a problem for black & white photography anyway. This lens is reputed to have a bluish cast for use with black & white film and it was corrected promptly with the release of it’s successor. I would not bother about that for using this with digital since WB isn’t an issue anymore with digital photography.

Focusing this thing on walking people can be a challenge because of the long focal length, your subject can easily go in and out of focus as you can easily see from my people pictures above. Some of the pics are barely not in focus but when you nailed it somewhat, like the picture of the lady in the bike then you are in for a treat. That picture was shot at f/5.6 and she is somewhat in focus, the lighting is what I liked about this shot. Pity it has to be just a candid shot of a random lady on a street and not a model!

img_2867This lens is heavy but it balances very well with most Nikon cameras that are big enough, from the Nikon F to the Nikon D5. It is a very well-balanced lens so it doesn’t feel heavy at all even on a small camera like the Nikon Df or on the film Nikon FM/FE series of cameras.

With the Nikon Df, I don’t need to convert the aperture ring to make it work on a modern Nikon camera. This is a pre-Ai lens and pre-Ai lenses that have no screws at the bayonet don’t have the much sought after factory Ai kits so the only way you can use this on later manual film Nikon cameras like the FM2 & FE2 and the majority of Nikon’s DSLRs is to convert this to Ai. I made this guide on how I went about doing this on my pre-Ai lenses, check it out. Before you convert any of your pre-Ai lenses to be Ai-compatible, be sure to think through it very well first because this is a destructive process and there is no going back once you’ve removed any material from it.

The Nikkor-Q 20cm f4 is a nice lens and the focal length sits comfortably  with my 50mm and my 28mm. These 3 lenses is my walk-around combo as far as minimalist lens setups are concerned.

The 28mm FOV is just wide enough for many things like landscapes and the usual urban architecture and it also serves well for street photography.

The 50mm is a general purpose fast prime lens for just about anything. It’s very hard to ignore the usefulness of a fast 50mm prime.

I just put these lenses in my bag and I am set. I would even add a film camera if I am in the mood to shoot film. I haven’t been shooting film much lately because of the cold weather. I hate developing film on colder weather, that’s why.

I probably wrote more than usual this time, I got carried away because I really like this lens a lot. I will try to give you whatever I know about something but I am sure that I will miss out on some things so if you noticed something or want to add some bits then please say something in the comments section. I appreciate Mr. Charlie, Roland Vink,etc for their input and corrections. Let’s begin with the disassembly!

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 (Lens Barrel):

Dismantling this lens is not too difficult if you are familiar with Nikkor primes and it has a lot in common with the Nikkor-Q 200mm f/4 that replaced this lens. You can even think of this lens as a GIANT version of your usual Nikkor-S 50mm f/1.4 prime if you wish because this is basically what it is – an oversized prime lens.

img_1578The only things that gave me trouble are the copious use of glue on this lens and the use of slot (-) screws. Slot screws are annoying to deal with and can be easily stripped if you are not careful and the liberal use of glue means that you will need to use more alcohol on the screws and threads. If alcohol isn’t strong enough then you should use acetone or MEK.

The helicoids for this lens are big so you would require more grease to lubricate it and the focus throw is kind of long so you would like to use a lighter grease for this. If the helicoids feel gritty for some reason even after you have cleaned them then you should go ahead and use a stiffer grease. This will make the focusing stiffer but at least it feels smooth!

img_1579Extend the hood and rotate/position it until you see this little set screw. Set screws serve as pins that dig into the part underneath so you cannot unscrew anything off accidentally.

img_1580Here is another one. There are 3 of them altogether.

img_1582Using a rubber sheet or a grippy rubber glove, unscrew the front ring but be careful not to damage the front element while doing so. It can be difficult because this part might have been glued or decades-old dirt might have solidified.

img_1583Be careful separating the hood from the rest of the lens, it houses a small mechanism for the clicking action and the parts are easily lost when the parts go flying across the room.

img_1584The mechanism consists of a pellet, brass cap (not shown) and a sprint. The pellet sits on top of the brass cap which serves to protect the spring. These go into the hole and it can be a pain to put it back when reassembling the lens.

img_1585Now with the hood gone, you can now strip the lens further. Remove the screws (circled) from the focusing ring and just pull it pff the lens. It can be hard to pull since solidified old grease can bind things or glue might have been used on this part.

img_1586You can skip this part if you want to remove the objective in one piece but I wanted to keep the front elements safe so I removed this part early in the disassembly. Locate this tiny set screw and remove it.

img_1587You can now unscrew the front barrel once that thing is gone. Keep this safe because it has the front elements in it!

img_1588Now, off to the rear. Unscrew this long screw from the aperture ring. This screw serves as a pin that connects to the aperture fork inside so it rotates as you turn the aperture ring.

img_1589Now that the screw is out of the way, you can remove the aperture ring from the rest of the rest of the lens by unscrewing it but while doing so, count how many turns it would take to remove the aperture ring and put that on a piece of paper. This is how many times you will turn your aperture ring when you reassemble your lens later.

img_1590Wipe off all of the old grease from the threads and locate these screws and remove them to get rid of the bayonet mount.

img_1591The bayonet mount can be pulled off safely once the screws are gone. The stop-down lever has a big and beautiful fork. Nikon probably needed to make this big since the simple and straight design that we usually see wouldn’t work with such a big lens and it may bend.

img_1592The metal sleeve can be removed by unscrewing the 3 screws securing it (circled). Just look at all that old grease and fungus.

img_1593Once the sleeve is gone, locate these screws and carefully remove them. The helicoid key is secured by these 2 screws and it is essential to remove the helicoid key to proceed.

img_1594You may need to rotate the helicoids to get the helicoid key out and whatever you do, don’t remove it from the slot. If the slot gets damaged then you will end up with a rough feeling sensation every time you turn the focusing ring.

img_1595OK, I know that we should have done this earlier so I apologize. Remove these screws (3) to free the objective’s casing from the rest of the lens.

img_1596The objective can now be removed safely. Store it somewhere safe and I advise you that the front barrel be re-attached to this if you got rid of it earlier like what I did.

img_1597Now, it’s time to separate the helicoids! Begin by separating the central helicoid from the outer helicoid and NEVER forget to mark where they separate! This is the same place that they should be mated again when you reassemble it. I placed my mark to coincide with the centre line of the lens, this will make it easy for me to identify where it should mate later.

img_1598Next, separate the inner helicoid from the central helicoid and as usual, mark where they separate. Observe where I placed my mark and you should get the idea.

img_1599Once the helicoids are gone, you can safely unscrew the ring that has the aperture fork in it. The threads are fine and it would be wise to handle this carefully.

Disassembly (Objective):

The objective of this lens is huge! Glue was used on many of the threads on my lens so be careful and exercise patience. The optical design of this lens is really simple – 4 in 4. It’s basically saying that there are 4 separate lens elements arrayed in 4 separate groups. If it’s 4 in 3 then it means that 2 of the lens elements are glued together to form a single unit.

The individual elements for this lens are also huge and some are even bigger than an Oreo! Having mentioned the size of the lens elements it goes without saying that they are heavy so be careful not to drop any into the floor by accident!

img_1600Here is the objective. This is probably the biggest casing found in a Nikkor that I have dealt with so far. I have opened bigger lenses but the objective doesn’t come off like this. If you recall in the previous steps, I removed the front barrel early in the disassembly process. If you didn’t follow what I did then you should get something like what you see in the picture above. It doesn’t matter which way you went anyway so don’t worry.

img_1601I started working from the rear but it doesn’t matter which side you start with. There is a ring retainer securing the rear element and I simply unscrewed it with my barehand. If it is glued then you would have to place a drop of alcohol/solvent on the threads and wait for it to work on the glue before you attempt to remove this ring again.

img_1602The rear element can be removed by using a lens sucker. Make sure not to drop this on the floor after you got rid of the retention ring!

img_1603The rear cover of the case can be unscrewed easily. If it didn’t then just do the alcohol trick again on this.

img_1605The front element is being held by this ring which you should saturate with alcohol first as it’s usually secured with glue. Use a lens spanner and carefully turn it counter-clockwise. I would really be careful if I were you since the front element is exposed.

img_1606The front element was removed using a lens sucker. Note that I used a sharpie to mark the leading edge of the lens. I do this to help me identify which side should be facing forward when I reassemble the lens. An element facing the wrong direction can be disastrous!

Notice that there is a gasket right after the front element. Do not lose this rubber gasket.

img_1607The 2nd element should also be removed by using a lens sucker. As with the front element you will definitely want to use a sharpie to mark which side faces where. A simple dot is all that you need. I even use a series of dots to note which element number it is.

img_1608I am sure that you have seen this before. The front barrel can be unscrewed from the main casing after you remove it’s set screw. The chrome sleeve is glued to the barrel and it will come off if you soak it in alcohol overnight. Underneath it, I found gunk and fungi.

img_1609Now it’s time to remove the 3rd element. Use a lens spanner or a lens opener with the long bits and sink the tips into these dimples and rotate this ring counter-clockwise.

img_1610The ring should be carefully removed carefully to prevent scratching the 3rd element. You will also need to be careful at this point because the 3rd element can fall into the floor.

img_1611The 3rd element is seated into a recess and it can be a snug fit. If your fingers can fit into the case then you can simply pick it off. Notice the sharpie marks that I made.

img_1612And here it is – 4/4 (4 elements in 4 groups). You can’t get any simpler than this unless it’s a Nikkot-T. I store them in their proper order with the front surface facing up.

Disassembly (Iris Assembly):

I would normally not bother with the iris assembly but I guess I had no choice when with this one. The iris is gummed up with oil and the only way to fix this is to strip it down to it’s bare components and clean it it thoroughly.

The blades were cleaned by wiping them with Zippo fluid individually. You should use a lint-free tissue for this so you won’t leave any lint on the blades and while doing so, you should be careful not to bend any of these as a bent blade will easily make your lens a junk as it will only be useful wide-open since the iris will not open and close properly.

The iris assembly has couple of precision adjustment points that you have to be very aware of so before removing anything, be sure to make small marks or take plenty of photos.

img_1604Yuck, just look at all that oil! It’s oilier than KFC but not finger-licking good at all.

img_1613Before I dismantle the iris, I marked it first so that I will know how these things should be aligned later during reassembly. This is a precise adjustment point so I am not taking any chances. It’s true that a skilled repairman leaves no marks but I am not a skilled one so it’s okay I suppose. Better safe than sorry.

img_1614Once you are satisfied with your marks, remove these 3 screws from the objective’s case. It is used to secure that ring that we just marked in the previous step.

img_1615The ring can be removed by using your fingers. Be careful not to damage the iris blades! It can be tight be tight so don’t use too much force or you will lose control. That lever you see in the ring is used for stopping-down the iris.

img_1616Now, it’s time to remove this brass ring! But don’t get too excited because you will have to follow the next step before you can remove this safely.

img_1617Look for this tall-headed screw and be careful removing this. These types of screws can be delicate because of the short shaft and relatively long head. This screw is responsible for connecting the iris assembly to the aperture fork.

img_1618This brass ring is responsible for securing the iris assembly. Once you got this out then you have crossed into the point of no return. Do not point the casing down or the iris blades’ll fall down and you will risk damaging such delicate things.

img_1619Before I remove the rotation plate, I took the effort to take a picture of it as a guide later. It doesn’t matter wether the iris is open or closed.

img_1620The rotation plate can be removed easily by pressing on it’s lever from the outside of the casing to lift it up and once it’s up you can simply pick it using your fingernails or a pair of tweezers. Again, be careful not to damage the iris blades.

The iris blades can be picked individually using a pair of tweezers or dropped into a clean tissue paper on your palm.

img_1621Once the iris blades are gone, you can also remove this ring from the inside of the case. It’s used as a holder for the 3rd element as well as to hide the holes where the pegs of the iris blades should go into.


I am starting to get really familiar with this lens since I overhauled a few of these. I would say that it’s relaxing to overhaul this lens because of it’s simplicity but it usually takes me 2-3 nights to completely overhaul one just because of the sheer size of the parts. As you know by now, I do something called an “alcohol bath” to the individual lens parts. This is when I pickle the parts in an alcohol bath overnight to get rid of the smell, residue, fungi or anything nasty in it. I got this practice from watch repair where individual parts of the movements are soaked in a fluid overnight for the same reason.

img_1626The felt on the lens hood had to be replaced as well. Felt paper was ordered from Amazon because the local Japanese supplier went belly-up. A thicker than usual felt was used as a replacement for the 1mm-thick felt lining so my lens hood feels snug and it will not move easily when extended, I like it nice and tight. Felt can be bought from the upholstery shop.

There are no adjustments for infinity focusing on most early Nikkors for the F-mount so if your lens isn’t focusing all the way to infinity properly then you definitely made a mistake here or there during reassembly. This is how tight Nikon’s tolerances were back in the days.

As you can see from the pictures the lens is damn oily and the oil even got it’s way into the iris assembly so to prevent this from happening again, just use enough grease so you have a thin film of it over the helicoids and not slather it like butter on a steak.

Thank you for supporting this site and I look forward to your support in the coming years so please share and spread this site so we can get more hits. I just got a notice from several sources that the domain and subscription has been renewed this year and thanks to all of you who are helping me support this site we are able to pay it automatically, we can move to a bigger image-hosting plan in the future as well because I noticed that we are running low on server space.

I sure had a lot of fun with this lens and I hope that you overhauled yours successfully and I bless you with a HAPPY NEW YEAR and plenty of prosperous things to come our way this 2017, the year of the fire rooster. Love, Ric (and family).

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.


2 Comments (+add yours?)

  1. Trackback: Repair: Nikkor-Q 200mm f/4 | Richard Haw's Classic Nikkor Maintenance Site
  2. Trackback: Internet Nikon Repair Resources – My Take on Photography and Diving (Underwater Photography Mostly)

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