Going Long: Nikkor 200mm f/4 AI

A 200mm can be a useful focal length in the bag, albiet a less frequently used length. However the modern and autofocusing xx-200mm zooms are heavy and expensive and therefore options to satisfy the 200mm can be better sourced from the legacy Nikkor AI/AIS catalog.




The main options in the manual focus lens line up for the 200mm medium telephoto range narrows the scope to a few lenses:

• Nikkor 180mm f/2.8 ED AIS or f/2.8 AI
• Nikkor 200mm f/4 AI/AIS

The 180mm f/2.8 ED AI-S has universally better reviews, is a stop faster and has an ED element for improved CA control but for the infrequent use cases it may not be worth the premium in terms of size/weight (13cm/800g vs 11.8cm/580g) and cost over the 200mm f/4 so the 200mm won.

The very useful Nikon lens serial number site notes the 200mm f/4 had 3 different production runs: 2x AI (710155-739174, 738930-858563), from 1977-Oct 81 and 1x AIS (900747-980088) from Nov 81-Jan 96. Scouring eBay, the costs of the 200mm f/4 AI varied widly between 65-140 GBP, with business resellers pushing their items even higher. Optically, they share the same formula:


^{(c) Nikon - 200mm f/4 optical cross section}

Richard Haw documents cleaning the optics of this lens is not too difficult but as usual requires the right tools and MikeNo62 shows this on the following YouTube video:

The copy I found had a higher price point but was from a private seller and when it arrived it was in great condition with clean optics. The lens is nice and compact (~13.2cm with hood extended) and does not draw unnecessary attention to itself unlike the modern day xx-200mm zooms: for comparison, it's a little shorter than the Nikkor 24-70mm f/2.8 but is significantly less bulky.




^{200mm f/4 AI vs 180mm f/2.8 ED AI-S size comparisson}

The lens has a 52mm filter thread and reasonably light with a minimum focus distance of just under 2m. On DX, you're stepping back a little (3-4m) to get a head/shoulders.


^{tripod @ f/4}

Wide open and at 100% sharpness is quite good but focusing accuracy is difficult given the risk of camera shake at this focal length. Stopping down clearly helps although it's not a significant change.

^{100%, f/4 liveview focused}

Like a lot of other Nikkor AI lenses (excluding the 20mm f/3.5 AI), the 200mm doesn't handle back lit scenarios well resulting in veiling flare. Colour rendition is pleasing and saturated and out of focus areas are not distracting although I'm not sure it's good - certainly the more modern and faster 85m f/1.4D does a better job at their respective maximum apertures but even at f/4 I think even the 105mm f/2.5 AI-S has a little nicer OoF areas.



^{1/320th @ f/4}

Helicoids

^{UPDATED 2024}

Servicing the helicoids is relatively simple in this lens but some of the helicoid screws etc may be very difficult to remove due to epoxy etc and require soldering iron and patience. I ensured I could unscrew the helicoid key screws before stripping further but importantly I reseat the screws until I'm ready to separate the helicoids.


^{strip to this stage, removal of bayonet and apeture ring to expose the helicoid keys}

You can minimise the time the internals are exposed (to avoid additional dust etc getting inside) but following:

• expose key sections for marking for helicoid separation
• unscrew the set screw above the barrel's serial number
• remove the focus ring rubber grip and the 3 focus ring screws
• unscrew the front barrel (including the front optical group - exposes the apeture blades)
• remove the focus ring
• reattach the front barrel / front optical group

Mark the helicoids and seperate:

• mark the helicoids aligned to inifity as reference mark
• remove the brass helicoid key
  
  
  
• remove the apeture activation screws to turn the helicoids past normal operating range
• collapse the helicoids and mark - even with marking separation, because of the potentially sticky grease, it can be sometimes difficult to know EXACT separation point - this reference mark when the helicoids are collapsed will give you a true correct position when remating helicoids
  
  
  
• separate the outer and central helicoids (the one with the chrome index ring) - turn the chrome index ring and mark on the central helicoid the separation point in relation to the infinity reference mark on outer helicoid block
• separate the central and inner helicoids - turn the central helicoid and mark on central helicoid the separation point in relation to the infinity reference mark on inner helicoid block.
  
  I left the iris activation mechanism in place although you can slide it up and off if its easier for you

Clean and regrease the helicoids:

^{L: original grease (not bad but some points were slipping as you focus) - notice that theres less grease on central helicoid as lens collapses towards infinity | R: cleaned helicoids}


• clean with lighter fluid and IPA
• central helicoid - VERY thin layer of light grease (Japan Hobby Tool #10) to mate with outer helicoid - when you remate, ensure there is not any heavy drag otherwise it will make for unpleasant focus action
• inner helicoid - the threads are quite coarse but again light grease

Re-assemble:

• re-mate the central and outer, checking the collapsed reference point is aligned. Keep collapsed
• re-mate the inner helicoid, verifying infinity ref mark aligns with inifinity on index chrome tab
• secure screws on iris mechanism - its easiest ending the helicoids a little, insert a driver to hold in place and then secure
  
  ^{same technique shown for helicoid key} Validate iris mechanism activates correctly
• secure helicoid key, ensure infinity reference aligned afterwards
• reattach focus ring - unscrew the front optical block again, slip over the focus ring, rescrew front optical block - at this point you may want to test if you have the right level of dampening offered by the new grease. Go and repeat any steps above if necessary if they feel too heavy/too light
• reattach apeture ring and apeture fork - focus to MFD to get easy access to drop in the apeture fork and then secure. Validate apeture opens/closes when the apeture ring is turned
• rettach the rear bayonet mount

As a long lens on a budget, this is pretty good - the prices aren't very high and the build and image quality are good but the real kicker for some might be the relatively slow f/4 aperture and resulting shutter speed. Depending on the use case (outdoor vs indoor recitals etc) this may be bothersome without legs or flash but for the price and optical features it's still a lesser known bargain in the Nikkor back catalogue.