Nikon 50mm f1.8 AI Lens – No. 1761389

The Nikon f1.8 50mm lens has always been well regarded. In pre-digital days, a ‘nifty fifty’ would have been the first lens owned by many photographers, mounted on a new 35mm SLR.

This example – 1761389 – came into my hands as part of a job lot of Nikon f-mount lenses bought from a well-known auction site. I was particularly interested in picking up an example of the 50mm f1.8 to try on a digital camera. The price for four lenses in very mixed condition seemed reasonable. I also wanted to learn what I could about lens repair and rehabilitation. A 50mm fixed focal length seemed like a good place to start. Richard Haw’s guide to disassembling this lens is superb so I set to studying his description and identifying the steps I might need to take (see link below).

A Bit of History

There have been various versions of this lens type beginning with the ai version, first produced in early 1978, of which 1761389 is an example. This lens type replaced the 50mm f2 version as Nikon’s standard lens according to Richard Haw’s review and repair guide. I found an excellent website that details the serial numbers of a wide range of Nikon lenses. This site is run by Roland, a New Zealander. He is still actively updating the site and claims that he has catalogued every Nikon lens that he is aware of in his database. He must be a true enthusiast, maintaining his site as a very welcome service to photographers who have an interest in Nikon’s rich history of lens making.

He says: “This page lists every Nikon lens version and sub-version I know of. Minor changes to internal mechanics, lens coating, engravings or electronics may not be listed. For each version up to four serial numbers are given: Start – Earliest – Latest – End. Start and End serial numbers are from Nikon Ai conversion lists, service manuals, catalogues and various books. The Earliest and Latest serial numbers are from lenses I have seen. They help confirm the Start and End numbers or indicate the range where the Start and End numbers are unknown.”

The database lists the following serial numbers for this lens type:

Start: 1760801
End: 2165418

Total Production Run: 404618 lenses

Production ran from January 1978 until October 1982.

Roland has seen lens 1760831, the thirtieth produced in the entire run. My conclusion is that my lens – 1761389 – is a relatively early example as it comes in at around number 588. Given that over 400000 examples of the lenses were made in just over four and a half years, it is likely that this example was in the first 0.15% of the total production run.

I don’t know how many 50mm lenses Nikon workers produced per week, but based on Roland’s figures and a production run of 58 months it must be about 7000 per month or around 1700 per week. Being the 588th in the run, it is quite possible that the lens was made in the first flush in January or early February of the initial production year. Whilst 1761389 is not the first example of the ai 50mm f1.8 lens, or even the thirtieth example, it feels like a small piece of Nikon 50mm f1.8 history being, apparently, a very early example of the product.

Current Condition of 1761389

The seller’s description was fair. The lens was relatively clean and tidy, the glass was clear, but it didn’t focus at all. The seller had made me aware of this in answer to a more specific request for information about its condition. The best I could do was to bring a shallow depth of field to focus at about 30cm. The following samples will show the sort of results I was able to shoot on a Samsung NX10 with a Nikon F mount to Samsung NX mount adapter.

I am a complete novice in this field, but my sense is, at a minimum, the infinity focus needs calibration. But there may well be more problems – misaligned helicoids – or, the worst case scenario, misreplaced or missing lens elements. There seem to be some issues with chromatic aberation which may or may not be related to the focussing problems. (Readers experienced in lens repair may be able to diagnose the problems more precisely from the images.)

There’s no evidence of the lens having been dropped or mistreated. However, a previous owner may have attempted a repair or service and left the lens in worse condition. There doesn’t seem to be much to lose by having a go at restoring it to something like its original condition. Of course, with my limited knowledge and skills, I may be unable to redeem the lens, but I will have learnt along the way and been part of 1761389’s journey.

Reflections

How many photographs have been taken with this lens over its near fifty year life? Weddings, parties, portraits of families, children at play, holiday snaps, landscapes, cityscapes, flowers, pets, domestic scenes. Images out of focus, in focus, under or overexposed, perfectly exposed, misframed, beautifully composed. For how long was 1761389 forgotten in cupboards, lofts or cardboard boxes, and then brought into the light after months, or perhaps years, to capture another fleeting moment. I would like to try and repair 1761389 so that its story may continue.

Follow Up

Following Richard Haw’s instructions I disassembled the front of the lens. This gives access to the focus ring so that it can be removed. I cleaned some of the grit from the focus thread using a cloth and isopropyl alcohol. The focus ring now turns much more smoothly, and without the sense of crushing sand. I couldn’t sort out the focus at infinity using the method described by Mr Haw so I reassembled the lens and took some further test shots. I don’t know if there’s any objective difference in the quality of the images but at least I didn’t do more harm! My sense is the lens will need a full disassembly so that the helicoids can be re-meshed correctly. I won’t have time to work on the lens for some weeks, but I am encouraged and think that I might be on the right track.

Resources

https://richardhaw.com/2020/05/23/repair-nikkor-50mm-f-1-8-ai/
http://www.photosynthesis.co.nz/nikon/serialno.html

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