Nikon Non-AI, AI, AI’D, AIS…. oh my. Part 2.

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And here we are again, at the cusp of further discussion regarding the Nikon F lens mount.  Part one of this Codex article detailed the various Nikon F mount revisions that have occurred through the years.  While there have been numerous modifications to the F mount, it has remained essentially the same mount since its inception in 1959.  If you were to raise your hand at this point and ask if this meant you could use any Nikon lens on any Nikon camera the answer would be…mostly, but there are exceptions.  These exceptions break down into three main categories: mounting, metering and focusing.


It is true that the F mount has remained basically unchanged for over 50 years. However, the universal rule that one Nikon lens can mount on any other Nikon body has one big exception. Due to several modifications done to the mount (and the associated cameras) over time, early Non-AI lenses should not be mounted onto all AI-era or later bodies.  The reason for this lies in a small lever that sits around the lens mount on the camera body.  This lever was introduced along with the AI modification to the lenses.  When a lens is mounted the lever recesses into the notches cut into the base of the lens mount and allows aperture ring information to be communicated to the camera’s meter.  The key point here is that the lever recesses into those available spaces cut out of the lens.  A Non-AI lens does not have these notches and when one attempts to mount a Non-AI lens onto a later camera they jam this lever into the body.  At best this leaves the lever out of place and the meter reads incorrectly.  At worst it breaks the lever and results in a hefty repair bill.


The AI lever on some Nikon bodies makes Non-AI lenses unmountable without damage to the camera body.

This is true of both Nikon film and digital cameras.  With DSLRs many of the more consumer grade cameras (think lesser expensive bodies) have no such lever meaning they can mount either Non-AI or AI (and later) lenses.  More professional DSLRs have this lever on the camera’s lens mount meaning they should only be used with AI or later lenses.  Do not mount a Non-AI lens to your D800!

A few Nikon cameras (such as the F3, F4, FE , FM and the new DF) allow the user to swing the lever out of the way, clearing a path for the mounting of a Non-AI lens. The trade-off for this is the loss of meter coupling with the lens.  If the camera has a depth of field preview this can be pressed to engage stop-down metering.


Some AI Nikon bodies have the ability to flip the AI lever up and out of the way, allowing the mounting of Non-AI lenses. These levers must be unlocked by depressing the small silver button in the lower right corner of the red rectangle above.


Ok, so you have that lens successfully mounted, all is golden now right?  Not necessarily.  Next up is the question of metering.  Some Nikon bodies will not meter properly with various Nikon lenses mounted on them.  This is especially true of Nikon DSLRs.  Lower end DSLRs without the coupling lever on their mount were mentioned above.  These cameras can mount either AI or Non-AI lenses safely.  But if you mount any lens that is pre-AF (any manual focus lens) the camera’s meter is disengaged.  You will have to either meter with a hand-held meter or guess and check.  Furthermore, the only exposure mode you will be able to use is M (manual).  It is important to note that the lens will still function properly in terms of aperture and focus, there is just no metering in-camera.


Some Nikon bodies lack the coupling lever, making them safe to mount both Non-AI and AI lenses. However, this is often done at the sacrifice of metering.

If you have a more professional DSLR like the D700 – which will only safely accept manual focus lenses of the the AI variety – then you are in better shape.  These lenses couple with the metering lever on the body of the camera and allow aperture information to be conveyed to the camera’s meter and voila!  You have metering capabilities with that 20 or 30 year old lens as long as you stick with the M (manual) and A (aperture priority) exposures modes.  S (shutter priority) and P (program) will not function with older, manual focus lenses.

On the film camera side of the equation, if you own a Nikon N55, N60, N70 or N75 then neither Non-AI or AI (and by extension AI-S and AI’D) will meter on these bodies.  In the case of these cameras, if you want to use the on-board meter you will have to stick with AF lenses.


It goes without saying that if you mount an old manual focus Non-AI or AI lens on an autofocus camera there will be no auto-focus capabilities.  Furthermore, some Nikon DSLRs (think the D40, D40X, D60, D3000, D3100, D3200, D5000, D5100 and D5200), in order to make smaller, lighter cameras have no auto-focus motors in the camera body.  These cameras rely on Nikon AF-S (or the very rare AF-I) lenses with the AF motors built into the lens to auto-focus.  You can mount other AF lenses on these cameras and they will otherwise fully function… as manual focus lenses.  Two other cameras to keep in mind are the  Nikon N55 and N60 film cameras from the early 1990s.  These cameras will not auto-focus with AF-S lenses, preferring AF or AF-D lenses.


With this knowledge added to your mental toolkit, you could potentially open up for yourself a whole generation of Nikon lenses for your body of choice. If you’re careful about mounting, flexible on metering, and comfortable with manual focusing, your options will greatly expand. There’s a lot of great Nikon glass out there; you might as well take advantage of it all as much as you can.



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