Another Well Regarded Legacy: Nikkor 28mm f/2.8 AI-S

The 28mm f/2.8 AI-S is a well regarded lens from the early 1980s that is still available new today. But what's the point of this compared to, say a 24-70mm f/2.8 zoom? And how does it fair for use as a walk-about or an environmental portrait lenses at/near wide open (f/2.8..f/5.6) apertures?


^{28mm f/2.8 AI-S}

Having spent a lot of time in the normal to short telephoto focal range I wasn't particularly sure about how I'd approach a wide angle lens for 'every day' or environmental photos. Sure, a 50mm is a reasonable choice but I wanted to frame things with a different perspective at the wider end - having scanned my catelogue of photos made with a 24-70mm it was clear I had a preference for the FF 28mm FoV when shooting people: the 24mm always felt too wide with difficult in composing effectively with people and 35mm didn't feel wide enough away from a 50mm.

So the search was on. Having recently picked up a 20mm for dual use as a wide for FF or as a walk-about ~28mm equivalent FoV on DX I started to look for a suitable 28mm prime that could be ultimately used on FF: sometimes you just want something lighter than a 900g zoom lens.

The Nikkor options (new and legacy) for the 28mm focal length is reasonable wide:

• 28mm f/2 AI/AI-S ^{1977 - 2005}
• 28mm f/2.8 AI ^{1977 - 1981}
• 28mm f/2.8 AI-S (0.2m min focus distance) ^{Aug 1981 - 2020}
• 28mm Series E f/2.8 AI-S ^{1977 - 1985}, f/3.5 AI-S ^{1977 - 1983}
• 28mm f/1.4G, 28mm f/1.8G, f/1.4D, f/2.8D

The AF focus lenses were mostly immediately discounted given their cost (all of them), apparent focus shift problems (1.8G)- the main reason I've started to hate the 50mm f/1.8G) - and poor optical performance (2.8D). Therefore it was back again with manual focus lenses. The Nikkor 1000 Nights tale regarding the 28mm f/2.8 AI-S provides a good read for why not to consider the Series E lenses: they were a cheap consumer line, whilst had an improved optical formula from the pre-AI iteration, were not a match for the AI-S.

And the choices were quickly narrowed to the Nikkor 28mm f/2 AI or the Nikkor 28mm f/2.8 AI-S.

NB: we have discontinued the f/2.8 AI version of this lens as unlike many other AI to AI-S upgrades, the 28mm f/2.8 AI and AI-S do not share the same optical formula: the reason for the optical upgrade is alluded to in the Nikkor 1000 Nights tale with the desire to improve the optics from the Series E which again was already supposed to have bettered the AI design.

The f/2 AI/AI-S vs f/2.8 AI-S: our purpose

The Bjorn Rorslett summary of both lenses are positive with other online commentary drawing the conclusion that whilst both are sharp and have CRC elements to allow for extended close focusing, the f/2 variant has better mid-far performance with better flare/ghost resilience whilst the f/2.8 is better in the close-near performance.

Given that I intend to use the lens mostly with people as the main focus the f/2.8 AI-S was the one - classic landscape properties (good infinity and corner sharpness at f/5.6 and smaller) for lenses don't matter so much as I'm typically using the lens wide open to f/4 perhaps f/5.6.

Cleaning the 28mm f/2.8 AI-S

The 28mm is available new (in limited quantities) it's retailing for ~610GBP (Nikon UK online store is asking for another 130GBP!), European eBay prices for these (2nd hand) lenses tend to be in the 130 - 185GBP range with absolute mint items touching 200GBP. I found a near mint item that was mechanically sound, smooth focus and elements clean of nasties (shining LED light through the front and rear elements and observing from the opposite end) but was a little dirty with rear and front elements needing a good optical clean.

There is a great resource from Japan based Richard Haw detailing the procedure to tear down and how to access the lens elements. For most folks, if we're cleaning we're hoping to simply cleaning small dust from the lens elements which are arranged as 8 elements/groups but in 3 different optical blocks within the lens barrel: front/CRC block, (4 elements) middle block (1 element) which is buried behind the first block and in front of the aperture mechanism and finally the rear block (3 elements).


<sup>(c) Nikon - 28mm f/2.8 AI-S optical cross section


exploded view, via photo.net user MFreeman</sup>

Because of the location and arrangement of the middle block (it's screwed in and buried in the lens) you'd hope to not need to access this but the rear block may need a little attention. The tools to give yourself successful and easier access are a lens spanner with flat blades and a P0 sized JIS cross head screwdriver, like a Vessel 9900 P0-100.

Access to the front/middle optical blocks can be achieved by removing the front collar which is secured by 2 grub screw, accesible when the lens is focused at MFD. Once removed you have access to the front optical block that can be removed using a rubber tool pressed against the optical block's retaining collar - if this removes the collar without removing the optical block, there are spanner slots on the optical block to allow removal. Once the front optical block is removed, the internal optical block can be removed using a lens spanner but this is secured by lacquer that needs some IPA to dissolve.


^{removal of front collar, front optical block using and access to middle optical block}

Accessing the elements in the front optical block with require a rubber tool to unscrew the front and rear collars; the rear collar is only to access the 4th element whereas the other elements can be picked out with a lens sucker - there are spacer rings that also need removal

^{removal of collars to access elements in front optical block}
The CRC mechanism causes the front element both rotate and to shift in/out of the lens barrel. The front element will recess into the lens when focusing towards infinity leaving a gap between the front nameplate/ring (that has the serial number) and the front element - this gap can allow dirt and particles into the lens: behind the front element optical block is main barrel that leads to the infinity brass focus adjustment ring that sits next to the helicoids. You can clear around there but it is tricky due to the space and need to remove various important helicoid keys.


^{left: focused MFD, right: focused at inf - notice the gap between front element and nameplate}



To clean the rear three elements in the rear block, it is easier if you remove the bayonet mount to get easier access to the rear element retaining ring. You can remove this retaining ring with the bayonet in place but you need to be careful that your lens spanner does not slip and scratch the rear element.

Set the aperture to f/22 and then remove the bayonet mount (3x '+' head JIS screws) and lifting up/out which will leave you access to the protruding rear element assembly - once the bayonet mount is removed, the iris will not change when moving the aperture ring. At this point a lens spanner can remove the rear retaining collar (you can do this by hand if not secured too tight) - note this ring screws directly onto the edge of the rear element so be careful not to over tighten when putting back together. With the first retaining ring removed you can lift the rear element out; next is a spacer ring (the 'cup/ridges' face towards the rear element) followed by two further elements that can be displaced by gravity but better with a lens sucker. Underneath the third and thickest element of this block (it's the one with the black inking on the edge) you will have (some) access to the aperture blades but not able to clean the middle optical group through them.


^{top L-R: removed bayonet (aperture index ring alredy removed), unscrew retaining collar. bottom right: rear element removed, spacer orientation}

Re-assembling the items are reasonably easy (clean the elements whilst wearing latex gloves and lens tissues is recommended if you do not have a lens sucker) but ensure the aperture ring and its associated aperture index ring with the silver tab are fitted correctly before trying to fit to rear mount, aligning the underside bayont latch with the silver aperture post mechanism.


^{assembly aligning aperture ring with f/22, placing aperture index ring and top view}

Helicoids and focusing smoothness

UPDATED: the internal helicoids control the focusing but is an advanced maintanence topic for this lens; over the years, the helicoid grease can dry out or get contaminated with dirt (dust, sand, grit etc) which affects the feel when focusing. The 28mm's helicoid maintanence is covered here.

Lens Performance and characteristics

Now that the lens is clean and usable, how does it stack up against our original objectives, performing at/near wide apertures for environment portraits/walk-about. Obviously these are my observations and there may be user error or lens sample variations at play affecting my conclusions.

Sharpness at different focus distances

The lens has a good reputation for sharpness in the close-mid range but what does that really mean. At minimum focus distance (0.2m) its very good wide open, although this is just an additional benefit to me given I'm not composing with people at this distance.


^{f/2.8 min focus distance 0.2m}

Going to more comfortable distances for environment portraits, we're probably looking at 0.7m - 1.7m distances. Remember this is a wide angle lens so it's not going to be used for head/shoulders.


^{left: f/2.8 focus distance ~0.8m, liveview focused remote tripped| center crop | right: f/2.8 | f/4 focus distance ~0.7m, liveview focused remote tripped}

When compared to the image at MFD, it seems that whilst sharpness is reasonable wide open, it doesn't seem as sharp but it's not bad.


<sup>FX | f/2.8 focus distance ~1.2m


FX | f/2.8</sup>

Going further out with a subject at 1.5m and beyond, I'm finding it difficult to obtain the same level of sharpness compared to the 0.7-0.8m distances. There could be a differing reasons for this, including the inability to focus (although my test images were tripod/liveview) or the contrast at those distances for smaller objects prevents showing absolute sharpness. I'm still to decide.

<sup>FX | f/2.8


100% crops of areas of focus (click for full size)</sup>

Finally going towards infinity (again wide open) I'm finding details a little mushy, not kit-lens mushy, but its very clear its not as good as in the 'close-mid' distances. Details get better as we stop down but at infinity it never gets to the same performance as close-mid.

This lens sample therefore seems to live up to its reputation of being very good at close-to-mid distances (which I'm defining as 0.2m-1.3m) for sharpness, colour rendition and contrast but further out than these distances the lens is merely ok. These observations don't really affect me as for my intended usage I would prefer near-mid performance gains.

Flaring and Ghosts

Flaring and ghosts are present wide open and provide some interesting patterns but not a big issue with veiling flare although there's a little loss of contrast and doesn't compare to the performance of the 20mm f/3.5 AI in this regard.

<sup>20mm f/3.5 AI: left, wide open | right, f/5.6


28mm f/2.8 AI-S contrast and flare/ghosts: left, wide open | right, f/5.6


28mm f/2.8 AI-S at f/2.8 (cropped): sun at right edge of frame</sup>

Out of focus rendition

Whilst bokeh isn't a massive consideration for this lens (it's a wide angle lens!) its rendition of out of focus areas are nice and unobjectionable - close up, bokeh it's very good.



^{out of focus renditions at MFD}

Lens Hood

The official lens hood for the 28mm f/2.8 is the metal screw-in HN-2 which, based on Rich Housh's data, stands at 15.3mm high and 71.5mm wide. Using circular polarisers (with their own filter threads) is generally not a problem except for potential vignetting caused by the profile of the filter itself.


With the hood installed the original clip on 52mm lens cap can still used although it can be frustrating given the tight fit - a modern centre pinch lens cap is easier to fit.

General Use

The 28mm on FF is my preferred wide and performs as expected. On DX, its FoV is 42mm equivalent which is a neither here nor there for me: as noted earlier, it falls in that zone between 50mm and 28mm and it's arguably even worse then a 35mm given it's not even that wide - but this is all irrelevant if you're used to seeing in the classic focal lengths.

Compared to a modern 24-70mm at 28mm and wide open

Now various forums posts will make statements along the lines of: the 28mm f/2.8 AI-S is super sharp/sharpest lens ever. Whilst I've seen in my sample to be reasonably sharp at/near wide open, when I compare this to a Nikkor 24-70mm f/2.8G at 28mm and the same apertures, I'm easily convinced the modern day zoom performs better. Both lenses produce nice and sharp images but they are different with the modern day zoom having a little more contrast and a little more saturated colours - skin tones in particular are better on the zoom.


^{Nikkor 24-70mm f/2.8 @ 28mm f/2.8}
But, the old timer with optics designed for 1981 is not embarrassed and we need to recognise this is a comparison against a pro-level modern day optic (who's performance, IME, is optimised in the wider end of the zoom - at the long end of 70mm, the sharpness of the 28mm f/2.8 AI-S is better)

Is it worth it? From my lens sample, there is some overstated online exaggerations about the qualities of this lens but it's still a very reasonable performer. For the price paid (compared to the ~615GBP for new) it's provides an good optical alternative to the (better but heavier) 24-70mm zoom for the 28mm environment portrait use case.