Why no aperture control with Nikon 55mm f/2.8 AI-s on Nikon D3200

Question

It was pretty exciting to borrow my dad's old Nikon 55mm f/2.8 AI-s and try it on my Nikon D3200. I have to use it in full manual mode, but it gets great results! Amazing how a lens designed in 1979 still works on the new cameras.

However, I was wondering why the camera does not allow me to control the aperture from the camera itself. I can see that the lens has an aperture control ring, which looks similar to the modern lenses I have. I also notice that there is a pin around 8 o'clock on the mount that gets depressed with the AI-s lens but stays free when using a modern lens.

It feels as if Nikon intentionally designed the D3200 to not do aperture control on this camera for AI-s lenses even though it may have the capability to do so. Is that a correct assumption? If yes, then I was just curious, why would they want to do that?

Answer 1

Yes, the D3200 (like all current low end Nikon DSLRs) can't control non-electronic lenses.

The meter (and viewfinder) are illuminated at the maximum possible aperture and calculating exposure would require knowing the difference between it and the selected aperture: hence the ability of higher end cameras to implement A and assisted M modes thanks to the use of a relative aperture sensor, as visible in this image

The opposite problem is readily solvable on AI-S (and derived) lenses given the proportionality between the stopdown lever and the resulting aperture, to the extent that some film cameras predating on-camera aperture control can fully use G-series lenses in the P and S modes!

This still requires knowledge of the minimum aperture (as implemented by mechanical sensors on those cameras), and the higher end digital bodies have exactly a menu feature for programming older lenses but without getting in-camera aperture control. How much of it is due to intentional marketing restrictions is up to personal preference.

If you're really inclined, some companies will add electronics to almost any lens imaginable.

Answer 2

There are actually very few cameras which can take full advantage of controlling the aperture of AI-S lenses, all of them were film cameras that have been out of production for long: FA, F-301, F-501, F4.

The mechanical linkages needed to communicate aperture with AI and AI-S lenses are missing on your D3200 (and other low/mid Nikon DSLRs). Higher end models (D7000 and up) can use the aperture setting on lens for metering, but not actually set it from body. Few AI-S lenses were made. Setting aperture on similar AI lenses would not be reliable since the pin's movement does not linearly correlate with resulting aperture.

Minimum support for the lenses makes sense, as the linkage would add complexity and cost while being useful to very few photographers. Those who have kept such old lenses will probably buy one of higher-end bodies now and aren't scared off by aperture ring, while those who acquire those lenses now do it exactly because it's cheap - so they wouldn't have wanted to pay extra for the camera either, and better support would increase demand and thus keep prices of old lenses higher.

Answer 3

From some quick research, it appears that the pin in question (or at least the lens in question) is able to communicate the selected aperture TO the camera, but not for the camera to control the aperture.