AI superior to AI-S?

[John Koerner]

Having switched to Nikon for about 11 months now, I've purchased a few AI-S manual-focus lenses, because these were the last-generation of Nikon's efforts, so my expectation was that the AI-S models would be superior, optically.

However, after reviewing the specs (thanks to Roland Vink's pages), it appears that the AI iterations of virtually every MF lens Nikon made (105mm and below) would be preferable to the AI-S version, simply because of a longer focus throw. If a person purchases a MF lens, it's because they enjoy the tactile pleasure of manual focusing, so surely the longer focus throw offers more pleasure + precision. Here are a few examples of some great, older MF Nikkor lenses:

Nikkor 6mm f/2.8
Focus Throw (AI): 90°
Focus Throw (AI-S): 60°

Nikkor 8mm f/2.8
Focus Throw (AI): 90°
Focus Throw (AI-S): 60°

Nikkor 15mm f/3.5
Focus Throw (AI): 80°
Focus Throw (AI-S): 50°

Nikkor 20mm f/3.5
Focus Throw (AI): 100°
Focus Throw (AI-S): 70°

Nikkor 24mm f/2
Focus Throw (AI): 160°
Focus Throw (AI-S): 80°

Nikkor 35mm f/1/4
Focus Throw (AI): 180°
Focus Throw (AI-S): 105°

Nikkor 50mm f/1.2
Focus Throw (AI): 180°
Focus Throw (AI-S): 110°

Nikkor 58mm f/1.2 Noct.
Focus Throw (AI): 230°
Focus Throw (AI-S): 140°

Nikkor 85mm f/2
Focus Throw (AI): 255°
Focus Throw (AI-S): 170°

Nikkor 105mm f/2.5
Focus Throw (AI): 170°
Focus Throw (AI-S): 140°

*** At 135mm and 180mm, they're the same at 270 ***

The point of this is, if a person is a collector, or is wanting to enjoy old-school MF lenses, why purchase the newer AI-S versions?

Did the AI-S versions provide anything "extra" to justify buying them? If so, what? Glass quality?

If not, and the glass quality is equivalent, then it seems the AI versions of these elder lenses would offer the greater manual-focusing experience.

Thoughts?

Jack

[Erik Lund]

It depends,,,

Ai:
Most have a more heavy strong design
Longer helicoils with more resistance in focus ring.
A few has 6 aperture blades that are a bit rounded at some apertures.

Ais:
Lightweight design.
Quick focus due to short focus throw.
Internal Focus.
More aperture blades can give better Bokeh.
Linear aperture, much better for CPU chipped lenses.

The different optical versions are indicated on Rolands pages by vertical lines, thin or heavy,,,

[Bjørn Rørslett]

Most Nikkors have participated in a slow evolution and improvement over the years. The AI/AIS divide is not always the most important step in this process. Thus one has to be careful when comparing lenses of different vintage lest the comparison is flawed due to other internal changes, not just focusing throw.

[Akira]

The only lens in this range that was fundamentally redesigned was 28/2.8.  Other lenses remained the same optically, except for the SIC coating applied to the later Ais models.



Ai 50/1.2 and Ai Noct 58/1.2 had only seven aperture blades, so Ais versions with nine blades could be preferable.  (The later Ai50/1.2 might have nine aperture blade, if I'm not mistaken.)

In the digital era, the longer focus throw is preferable, so I would go for Ai version except for the 28/2.8 and the above mentioned fast lenses.

[Peter_S]

peobably yes, AI lenses are mechanically and optically really very good.
If you chip your lenses AIS are straight on. AI lenses, at least most of them have about one stop offset in the middle aperture range. Means, you dial in f5.6 and your cam  closes the AI lens only to f4. You may correct it with -1 in your cam or with  filing the aperture lever, but means some additionally work.
Nevertheless I got some unique AI lenses:
20 f4: small and excellent stopped down to 11.
35-70 AI: sharp as it gets better than my AFD, except bokeh.
55 f3.5 micro: in macro better than my 55 f2.8 AIS
non AI: 135 f2.8 QC: perfect sharp and excellent  bokeh, maybe better than my 85 f1.4 AFD, got it for 15 bucks
and a real gem: 50 f1.4 auto sc.
and some more 🤔

Since I chip my manual lenses I use my AF and AFS lenses rarely.
It's a pleasure to use these lenses, especially if you clean theme and put new grease to the helicoids - perfect.

enjoy manual lenses
Peter

[Akira]

Pedro, or anyone who uses chipped Ai lenses, is there still any discrepancy between the set aperture and the metered value when you switch the camera mode to set the aperture on the aperture ring of the lens?

[Peter_S]

if you toggle to the lens aperture ring it's fine, I think it's command 60 if I remember right, but does not work with the D800.
With my other DSLRs it works fine.
But it's mostly only an one stop offset. I think it was so designed by Nikon to be sure the lens can close to the value set at the aperture ring. Using electronic lever control from the cam, from AIS on, the lever MUST be precisely adjusted. But there are some workarounds

[Bjørn Rørslett]

 

Pedro, or anyone who uses chipped Ai lenses, is there still any discrepancy between the set aperture and the metered value when you switch the camera mode to set the aperture on the aperture ring of the lens?

If the lens is true AIS, either operation should lead to the same result. However, why one would dial in aperture when the lens itself has an easy-to-use aperture ring is beyond  my limited imagination ...

For an AI lens, only setting aperture on the lens can yield consistent results.

All the above assume a properly installed and correctly  programmed CPU chip. A few ultra-wide lenses need trimming of the value of the exit pupil in order to meter accurately, amongst these first and foremost the 15/3.5.

[Akira]

Peter (sorry, I thought you were Pedro a.k.a. PedroS) and Bjørn, thanks for the reply.  That supports my memory.

[Bjørn Rørslett]

The only lens in this range that was fundamentally redesigned was 28/2.8.  Other lenses remained the same optically, except for the SIC coating applied to the later Ais models. ...

This blanket  statement is at variance what one may see inside the lens. Even though the official design is said to be unchanged AI>AIS, more than the indexing mechanism and focus throw might have been updated. One example is the 50/1.2, for which the rear element changed its size. Erik and I grew a few extra grey hairs when dealing with that lens.

[Peter_S]

the best way is as Bjorn said, unfortunately I can not toggle to the aperture ring with my D800😬.
Other cams work fine with command 60 and Dandelion.

[Bjørn Rørslett]

Strange. My D800 allows the aperture ring to be used, no problem at all?

[Akira]

This blanket  statement is at variance what one may see inside the lens. Even though the official design is said to be unchanged AI>AIS, more than the indexing mechanism and focus throw might have been updated. One example is the 50/1.2, for which the rear element changed its size. Erik and I grew a few extra grey hairs when dealing with that lens.

I know, that's why I said "fundamentally".  28/2.8 has seen a total optical design change between Ai and Ais.  I would say that the change in 50/1.2 was minor, even with respect to the lost color in your hair.

[Bjørn Rørslett]

The optical change prevented us CPU-modifying the lens we had planned, so was significant.

Nikon have a very long tradition of keeping the playing cards tight to their chest. A lot of the improvement are never published.

[Peter_S]

Bjørn,
its a problem with a Dandelion chip and a D800.
Better way to chip is your approach, but I didn't know this some years ago...
With a D700 you may toggle AI lenses to the aperture ring, no problem. Works very consistent.
Its in depth  discussed at pindelski.org.....