The f/3.5 AI-S was sunset in 1983 by which time the very well regarded 28mm f/2.8 AI-S had been released. Over time, the 28mm f/2.8 AI-S reputation (and its long production run) keeps it in conversations but if you were to consider a manual 28mm, is the slower f/3.5 worth considering?
The 28mm f/3.5 AI and AI-S lenses share the same optical formula but different barrel construction so picking up either is a good bet. Due to the internal changes to the AI-S version, Richard Haw states the AI-S is more prone to oil getting onto the aperture blades due to the helicoid and aperture being part of the same physical block - this is not the case with the AI. The AI and AI-S f/3.5 are nearly identical in size/weight but the AI has a 200 degrees focus throw compared to the 90 degrees of the AI-S
Performance
Incredibly, the 28mm f/3.5 AI lens is very sharp wide open with very good contrast in my comparison with the 28mm f/2.8 AI-S. This is indeed a surprise given the f/2.8 AI-S is renowned for sharpness and the slower and older lens is right up there wide open. Contrast seems a touch better on the slower lens too wide open but this gap closes as we stop both the f/2.8 AI-S.
centre crops, shot at 1.5ft - click for full size
The lens is quite flare and ghost resistant and similar to the f/2.8 AI-S in this regard, although the f/2.8 AI-S has nicer looking sunstars but maybe the f/3.5 AI is less prone to ghosts.
Infinity performance is a little mushy and the same for both wide open and f/5.6 and beyond down to f/11. I've recalibrated infinity focus with no change to the performance. Look at the yellow brickwork detail of the building on the left of the frame and the buildings on the horizon line for how it performance doesn't significantly improve as you stop down.
centre crops, shot at infinity - click for larger size
Objects that are not quite "infinity" tend to not be so mushy, so there's a question whether the resolution of the lens at infinity is in play. The two images below are at f/5.6 and not focused on tall blue building.
Objects in near-mid distances fair better - various images at f/5.6.
Bokeh is average, nothing special but there's not any jittery rendering which is positive.
28mm f/3.5 AI wide open, cropped, click for bigger
28mm f/3.5 AI wide open, cropped, click for bigger
Compared to the f/2.8 wide open, both at about 0.4m focus.
Asthetics
The AI lens was in production from 1977-1981 and common to most AI lenses the focus distance scale is on its own section of the lens (as apposed to being on the chrome grab ring) and as you focus from infinity to MFD the distance focus scale is further exposed. Asthetically I much prefer the AI-S lens where turning the focus ring does not extend/expose more of a focus scale. However the f/3.5 AI has a hybrid setup and its quite pleasing.
Notice as the lens is focused at MFD, more of the distance scale is exposed of the 35mm f/2 AI lens (as with many AI lenses). The 28mm f/3.5 AI handles this in a much more pleasing way IMO.
Pysically compared to the 28mm f/2.8 AI-S, we can see it has more of the future AI-S design language:
The f/3.5 AI has the longest focus throw of all the AI/AIS 28mms at 200 degrees although the f/2.8 AI-S has 170 degrees rotation, both are signifcantly longer than the f/3.5 AI-S.
Servicing
As with any aging 40+ year AI lens, repairing / servicing 28mm f/3.5 AI is almost inevitable and this lens is quite easy to work on. This lens constructions follows most wide-normal AI lens so if you've worked on the 35mm f/2 AI or the 50mm f/2 AI this will be quite familiar.Be aware that Roland Vink documents there are a number of iterations of the 28mm f/3.5 AI. Whilst this should not impact the main characteristics of the lens barrel etc, this should be noted. The documentation below is for a lens with a 18xxxxx serial number (the last iteration according to Roland Vink's data).
- To start, remove the rubber focus grip to expose a lacquer seal securing the focus ring. Apply acetone/IPA to the hole and wait before twisting off.
Once this collar is removed locate and loosen the grub screw on the objective retaining collar.
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Once removed, extend to MFD to access the set screw on the front lens retaining collar (including the nameplate) - once the retaining collar is removed you can remove the lens objective as a single unit and set it safely aside.
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Remove the rear mount and the aperture ring as usual - there are no gotchas here and can be lifted straihgt off - to expose the aperture coupling pin; unscrew this pin and pick out the aperture fork.
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Set lens to infinity
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Remove the 3x screws and lift off the focus ring. These 3x screw holes are where you'd adjust infinity focus post reassembly - the holes are on the central helicoid.
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From the rear, remove the chrome grab ring - you don't need to remove the ident spring if you're lazy, simply press it down before sliding the grab ring over. Next remove screws securing the focus distince scale and remove the same way - this distance scale also acts as infinity/near range stops for the focus ring. The helicoid screws are accessible without removing the distance scale but its easier to remove it.
- Mark an infinity alighment mark on the central and rear helicoids.
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The helicoid key has a lip that faces the rear of the lens. Remove the helicoid key screws and carefully extend the focus towards MFD so you can push the helicoid key out - store safely
notice that the central helicoid appears to have no reference mark - its there but the focus helicoids has been moved towards MFD to allow the helicoid key to be extracted
With the helicoid key removed, you can collapse the central helicoid to get a reference for reassembly but because of the 50 year old grease, this may not be 100% upon reassembly.
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Separate the rear and central helicoids, marking separation on the central helicoid as aligned the the rear helicoid (infinity) reference mark
- Separate the inner and central helicoid THROUGH the central helicoid (as the inner helicoid going to to the front of the lens). YOu can't separate through the rear. Mark the inner helicoid aligned to the (infinity) reference on the central helicoid
the seperation mark is there on the inner helicoid (its marked at the edge closed to my palm) - its just burned out in the specular highlight
- Clean the helicoids with lighter fluid, kitchen degreaser, kitchen dish soap and then final clean with IPA. Wipe down/away most of the grease first, perhaps with lighter fluid applied to a thick kitchen tissue
- Apply a very thin layer of NLGI #00 grease to the inner helicoid and remate - ensure this is smooth and light before remating the outer helicoid. On the central helicoid apply a thin layer of the same grease but adjust to taste as this will have the most impact on the lens's focus feel when fully assembled.
Remember to lightly grease the helicoid key and its slot.
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Once assembled to attaching the focus ring, do not secure the screws but go and calibrate your inifinity focus
Optics
The optics are set in 6 elements in 6 groups, with the aperture blades sitting behind the 3rd element. The elements are in set logically into 1st/2nd elements as one removal block and the 3rd element. The final 3 elements are extracted from the rear and aside from the usual lacquer on a first logical block, access relatively easy.
Nikkor 28mm f/3.5 AI optical cross section
The front element is easy to access behind its own collar onced you've removed the front retaining collar This collar maybe sealed so pay attention if it does not spin off easily - if it is sealed, its easier to apply the accetone behind the lip of the collar if you pull the entire lens objective out. With the collar removed, you can tip this element into your hand but be careful of the rest of the lens objective following if its still seated in the barrel.
The 2nd element does not need to be removed from it's housing to clean unless its got fungus at which point you'd want to clean the housing seperately. Only need to remove the 2nd element from the objective if you need to clean it's rearside.
The 3rd element and its housing is accessible if you remove the front optical block and its 2 elements. Again you'll need a lens spanner to remove but this element is seating into its housing and you can't separate them.
Be careful when removing the rear element - its almost impossible to tell which way it should face, although if you install it wrong test images will show you. As with all rear elements, be careful of use an air blower on the 2nd-last element - blowing on it will invariable kick up the spacer and element and can confuse you for orientation. Luckily the 5th element here is clear and the spacer has a flatter edge that sits on the 5th element.
5th element sitting behind a spacer
Conclusion
I was positively surprised by this lens, given it was positioned as a consumer lens, below the faster f/2.8 and f/2 lens but above the series E.There's varied writeups on the internet about this lens perofrmance but its difficult to trust most of those reviews. Bjorn Rorslett did give this a 5/5 but given his very positive writeup of the f/2.8 AI-S I didn't expect the f/3.5 to be that good. Contrast is good, sharpness is good and if I were to be casually looking at images taken with both I'd not easily identify the slower/cheaper lens. I don't like the far-infinity performance of the lens - I see details as mushy not matter the aperture - but near-mid is much better. Build quality is good and expected of Nikkors of time with its all metal construction.
Next, as a prospective owner, consider the servicing aspect of the f/3.5 AI vs f/2.8 AI-S. As seen above, servicing is relatively simple for this lens, whereas the f/2.8 AI-S is much more complicated to service with its rear helicoid access and internal CRC helicoid.
Certainly if cost was a factor (the f/3.5 AI can be found around 1/3/ to 1/2 price of the f/2.8 AI-S) there would be no hestitation in recommending this f/3.5 AI but even if cost was not, it'd still be worth considering. Yes the 28mm f/2.8 AI-S has some highly respected (and deserved) qualities but looking at this lens alone, you would not discard it given its own qualities.
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