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Repair: Nikkor 50mm f/2K (New-Nikkor)

Hello, readers! Sorry for skipping the past couple of weeks as I was busy with work. It was a very unremarkable month and all I did was work work and work. Couple that with a cold front and you get a very lazy and tired father. Apart from people messaging me that they saw my name in the latest Final Fantasy credits, this month passed on unremarkably and I would like to continue on that tangent by talking about an unremarkable lens today…

Introduction:

Today, we will be talking about the Nikkor 50mm f/2K (New-Nikkor) lens! I was busy in the past few weeks and I cannot decide on which lens I should make a teardown of so I made a poll and this one got the 2nd highest vote. It was such a boring month anyway and it’s just fitting that I make a teardown of a boring lens.

img_1443The Nikkor 50mm f/2K feels heavy and VERY well-built. This feels pleasant in the hands so I would sometimes use this lens just for the heck of it. It has the right heft and balances so well on all cameras without a built-in motor drive/grip.

img_2634Despite being a simple and bland standard 50mm lens, it is very well-built and feels more like a more expensive lens. It balances very well on both digital and film cameras.

(Click to enlarge)

As you can see from the samples above, this lens flares pretty badly and the blobs it forms can be annoying. You can use these flaws to your creative advantage if you choose to. But if the sun is not in the frame or close to it, the images it produces are pretty sharp. The first picture of the leaves will show you that it’s decently sharp and it can focus really close,too. It is a very utilitarian lens and is a very practical choice for anyone wanting a good lens for street photography. The strength of this lens in my opinion is that it’s good at everything to the extent that it doesn’t do one thing really well and that is just a nice way to say that it is a boring lens but useful lens. Would I recommend it? Yes, especially for the price that it is selling for these days. I can imagine that this is a great lens to couple with a Nikkormat or the Nikon FM/FE series of cameras. They both make for a light and compact setup. There is a really good write-up made by Nikon in this page and I advise that you read that as well.

img_1445If you pay attention to the glass you can see that fungus has made the inner surface of this lens it’s home. This is unacceptable to me so it has has to be cleaned. The helicoids were in poor shape as well because of the dry grease so a full overhaul is in order.

Did I say “overhaul”? Oh,yeah! You are here to see how it was overhauled! OK, let’s begin with the teardown!

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):

I have never opened up the Ai version of this lens but from the looks of it I can guess that the Ai version should be roughly the same as this one in engineering so this teardown will also be applicable to the Ai version despite being a K (New-Nikkor).

As usual with primes, we need to separate the objectives first while working with the lens barrel to avoid damaging the delicate optics in it. Before you attempt working on this you will have to be sure that you have the correct tools for the job such as screwdrivers and I’ll also warn you that you will need plenty of alcohol and solvents to soften up the glue used on this lens during assembly in the factory. Patience will get you thru this project.

img_1446Carefully remove the rubber grip from the focusing ring by wedging a small screwdriver or a toothpick under it and running it through the circumference of the rubber grip to loosen up the old adhesive that was used on it.

img_1447Carefully remove the rubber grip and be sure not to tear it. Older lenses have brittle rubber used for the grips and they tear rather easily. Notice the old adhesive in the picture?

img_1448Once the rubber grip is gone, you can go on and remove the front part of the focusing ring. This can be very difficult to separate because they are usually glued in place. Place a couple of drops of solvent or alcohol and let it work on the glue before you attempt removing that thing with a rubber sheet to add some friction to your grip.

img_1449With that ring gone, you can now access this small set screw. Unscrew that and store it in a safe place so you won’t lose it. These tiny screws can get lost easily, I warned you.

img_1450Now that the set screw securing the front ring is gone you can now proceed with removing it from the rest of the lens by unscrewing it.

img_1451The front ring secures objective so you can now pull it off from the lens barrel and keep it in a safe place while you work on the rest of the lens.

img_1452On to the rear of the lens. Remove these 5 screws from the bayonet mount. Be careful with these because they are usually secured with Loctite or some kind of adhesive. If the screws will not come off then drop some alcohol or solvent in it and wait for it to soften whatever was used on it before you attempt to remove it.

img_1453The bayonet should come off without any trouble since nothing is attached to it like a tiny screw or spring.

img_1454Next, remove the aperture ring. There are no screws attached to it unlike some of the early types of Nikkor lenses.

img_1455Let’s go back to the front. Before you remove the aperture ring, be sure to tale a picture of it first or make some marks. This is an adjustable part so you will want to take some notes for reference later during reassembly. These 3 screws secure it to the central helicoid and unscrewing these will allow you to remove the focusing ring.

img_1456And off it goes…

img_1457Next, we need to remove the chrome grip in order to access some parts underneath it like the helicoid key. Simply remove these screws to take it off.

img_1458OK, you got rid of the screws but the grip still won’t get off! The reason is because this tiny screw is in the way. Remove this screw to get it out of the way so you can remove the grip. This screw acts like a pin that connects the aperture fork inside to the aperture ring. This is a delicate part and is easily damaged to be careful.

img_1459The chrome grip is sometimes glued in place so you will want to use some solvents and a little bit of patience.

img_1460Once the chrome grip is gone, the sleeve with the scale can now be removed as well. Mine was glued into place and it took some solvents and effort to get this loose.

img_1461OK, after so many steps we can now finally access the helicoid key! Simply unscrew these 2 screws to free the helicoid key. Notice that the helicoid key is is mounted wide side-up. It was designed this way to conserve space I think.

The helicoid key is there so that each helicoid will maintain it’s position while you rotate the central helicoid.

img_1462With the helicoid key gone, you can now separate the central helicoid from the outer one. I made a few marks on the surface of the helicoids to indicate where they separated. This’ll help me later in determining where these should mate. Never forget this procedure!

img_1463For a thorough cleaning of the helicoid, I need to strip it down to it’s bare components. It’s also advisable to do this since you do not want old crud hiding in the crevices of the lens to contaminate the fresh grease that you are going to apply later.

To remove the aperture coupling fork and it’s ring, you will have to remove this brass ring. This brass ring can be annoying to remove but the easiest way that I can think of is to turn the ring until the ends are near the slot/rail of the helicoid key. Once it’s in place like the one in the picture you can use a small screwdriver to pick it out from the slot.

img_1464And there it goes. This part should come off easily since you already removed the screw in the previous steps. You can’t get this far anyway if the screw is still there.

img_1465Separating the central helicoid from the inner one requires that you remove this helicoid stop. This part limits the turning of the helicoid to it’s minimum and maximum distances. It is also keeping you from separating these 2 helicoids so we have to get rid of it.

img_1466Rotate the inner helicoid until the screws of the stop is revealed. Unscrew these 2 and then remove the stop. It may be glued in place so you may want to wedge it with a screwdriver. Just be careful not to damage the delicate threads.

img_1467The helicoids separate in this manner with the inner helicoid exiting from the lower part. Do not forget to mark where they separate. If you forgot to do this then you are an idiot.

img_1468The central helicoid comes in 2 pieces, the helicoid itself and the rotation limiter. This part  is used to limit the rotation of the focus ring in conjunction with the helicoid stop. Grease and old crud tends to accumulate under the ring so I open it up to clean it despite the effort and patience needed to remove this.

Before you do anything with this, make sure to mark it’s position by scribing a small mark on the ring and the helicoid to serve as marks to help you align this ring again later.

This ring is glued in the factory so I usually soak this part in alcohol first for several hours or overnight to dissolve the glue. Remove the 3 set screws and simply unscrew the ring off. If this doesn’t work then soak in in alcohol again until you think it’s OK to attempt again.

img_1469The ring should come off, revealing the dirt underneath it. Clean these thoroughly and be sure that nothing is left in there.

img_1470Going back to the front end of the lens, the front ring comes in 2 pieces. The name ring is also hiding some dirt underneath it so I unscrew it off to clean the underside of it.

Disassembly (Objective):

The objective itself is pretty straight-forward. There are no surprises so far but I will have to just warn you about accidentally dropping an element or two just in case. You will need a rubber stopper and a lens spanner for this job so be prepared. The rear element was sealed with paint and I will show you how I safely opened it.

img_1485Remove the front baffles to reveal the retention ring underneath it. The baffles should be removed using a rubber stopper. Do not use anything that’s not made of rubber on it and be careful not to damage the beautiful ridges milled into it.

img_1487The front elements group can be removed by unscrewing it off from the casing.

img_1488Use a lens spanner to remove the retention ring securing the front element.

img_1489My lens spanner has sharp tips so I scratched the metal surface underneath it. If you have a round tipped one then good for you.

img_1490Use a lens sucker to remove the front element and be careful not to drop this to the floor!

img_1491To make sure that I put the elements back together in the same order and direction, I used a sharpie to mark the leading and as well as a dot to indicate the element number.

img_1492The 2nd element group can be unscrewed from the case. The ring around it is usually glued to the 2nd element group on most lenses.

img_1493On to the other end. The rear elements group can be screwed off from the main casing. Use a drop of alcohol on the seams if it’s stuck.

img_1495To remove the 3rd element group, you will have to use a lens spanner to remove this ring.

img_1496The 3rd element group can then be removed using a lens sucker. Be careful not to drop it!

img_1497The rear element can be removed by getting rid of this retention ring but unfortunately, it is sealed by paint. I use the tip of a precision screwdriver to scour the the paint off so that I can drop some alcohol into the thread underneath it. Mind your fingerprints,sir.

img_1498A lens spanner should be used to remove the retention ring. Be careful not to scratch the delicate glass of the rear element!

img_1499Use a lens sucker to remove the rear element or drop it into your palm (and not the floor!).

img_1500To distinguish which element is which, I used a sharpie pen to mark the leading edge and the element number with a series of dots. Well, this lens is simple enough that you won’t get confused with which element should go where but this is going to be helpful once you work on a lens with more element groups.

img_1501And here they are, ready to clean! I cleaned them using the method described in my fungus removal post.

img_1494Well, my iris assembly still looks OK so I won’t be doing anything to it but if you needed to clean yours then you can start by removing these screws. I won’t bother with it if the iris is clean and working properly. Sorry if I can’t help you with this one.

Conclusion:

The lens is pretty straight-forward with nothing noteworthy as far as disassembling goes but I noticed that this lens is built better than most versions of this lens family. The build itself mirrors that of the more expensive mid-ranged (cost) primes in quality, something that most lenses today lack with all the plastic parts and such. After giving this lens the care it longed for, I can assure myself that this lens will last me many more decades before it decides to retire or need another overhaul. I love my manual Nikkors and I will sure make most of them family heirlooms in the future for my descendants.

This job will probably take you a whole afternoon to do, it isn’t stressful as long as there’s no stripped/rusted screws or anything of that nature which will require additional effort. I was slowed down by the glue used on several parts of the lens but that’s as expected and it is already part of my workflow to account for the time needed to fix that.

img_1471The aperture ring was milled so that I can use it with a modern Nikon camera without the risk of damaging the delicate aperture coupling tab. I milled it using the method described in this link. If you have the Nikon Df then you can use this safely on that camera.

img_1472To calibrate your infinity focus, rebuild the lens up to the point you see in the picture. With the focusing ring off and and the limiter ring in place but the 3 set screws loose. This will give you the chance to adjust it to your liking.

Focus the setup on a building or structure 4-5km away or even better, something further. Once the central focus point in your DSLR is centred on the far-away subject, focus the lens until the focus confirmation dot lights up. This is the correct setting for your infinity focus. Carefully rotate the limiter ring until it comes in contact with the helicoid stop and tighten the 3 small set screws to secure the limiter ring to it’s position. Now, focus on the far-away object again and see if the focus confirmation dot lights up again in the viewfinder. If it fails then go back a few steps and repeat the procedure again. I know it’s tedious but there’s no other way to do this. I usually go about doing this hand-held so a tripod isn’t necessary.

This article took longer to finish than usual since we had to cover the objective and it’s tear down. While this article didn’t teach you anything new if you are an experienced tinkerbug or if you have been following my blog for a while, it does help to know how things are put together so that you will have a guide just in case you need to fix one yourself and prevent any unwanted surprises. It’s also nice for collectors so that you will know if somebody is trying to sell you something from a bash.

Thank you very much for your continued support since that is the only motivation I get for making these posts and if you’re not yet a member of the companion facebook page, click on this link to get there and “like” the page so that you get updates every time something new is posted or ask for parts and advise from other members. That’s it for this week and I hope that you enjoyed this post. Love, 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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1 Comment (+add yours?)

  1. Trackback: Internet Nikon Repair Resources – My Take on Photography and Diving (Underwater Photography Mostly)

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