Nikon Lens Nomenclature

Confused ? If you are new to the Nikon line of photographic equipment, you may find yourself inundated with terminology and acronyms that leave you scratching your watch (or winding your head) in bewilderment. Hopefully, the following can take some of the mystery out of the process, it pertains to Nikons built after the rangefinder era. You need to know some definitions first.

ADR stands for Aperture Direct Readout. ADR is the small f-stop number that appears on a small ring at the very back of the later lenses. If you look carefully at the body of later model manual focus Nikon cameras, you may see a small window at the top of the lens mounting ring. Ambient, or surrounding light, is reflected off the ADR ring through the small window into the view finder, allowing you to see what f-stop you have set without removing your eye from the focusing screen.

AI stands for Automatic Indexing. AI allows you to perform metering with the lens wide open at it's maximum aperture (so you can see to focus with the screen at it's brightest) - then as the shutter is released, the lens "stops down" (or the aperture becomes smaller to what you have set on the ADR) to properly expose the picture.

Non - AI stands for the early bayonet-mount lens series that did not offer automatic indexing. You will often see these lenses offered for sale and described variously as "NonAI", "NAI (erroneously - NAI should stand for Nikon AI)", "Lenses with prong IC" or even "Nikon prong". One clue that a lens is Non-AI is when you see a description such as "Nikkor-Q 135/2.8" - The "Q" (or other letters) is the early designation that gives the number of elements in the lens.

Non - AI (The early bayonet-mount lenses)
	Solid "ears" (see note) on your lens indicate an Non-AI lens. These lenses can not be mounted on many of the later bodies without causing damage because the "ears" strike the body prism when you mount them. See the charts to determine if they will physically mount on your camera body. If the lens will mount on your camera body, then check if it will allow normal metering or if you are required to "stop down" the lens to meter. If you are required to "stop down" to properly meter, you first focus the lens at it's maximum aperture with a bright screen, then "stop down" to meter for proper exposure, then release the shutter. (Not very handy to do) Note: In some circles referred to as 'bat ears'.
	If the black outer rim on the lens base is solid all around the lens (no meter coupling ridge) you know it definitely is a Non-AI lens.

AI'd (Non - AI Lenses physically converted to AI after manufacture) and AI Lens
	When Nikon developed AI, users of the old lenses and bodies were not left out in the cold like many of the other manufacturers did to their customers. They offered factory alterations to Non-AI lenses so their customer didn't have to start over collecting lenses to mate with their "new" updated camera bodies. These alterations are no longer offered by the factory, but other folks do them still - see the links page for addresses. These "ears" have holes (see note) in them (as do later AIS lenses) and are mounted further out on the lens to clear the prism and allow mounting. A meter coupling ridge was added. Note : referred to in some circles as 'hog's nose'.
	If the black outer rim on the lens base has a rim (meter coupling ridge), the lens is either AI or AIS. Note the presence of the "ears" in this picture - Series E and AF lenses don't have ears as is the case with some late production AIS lenses.
	An original AI mount is shown at left - if the lens has been AI'd (or modified) from an older non-AI, it will not have the Maximum Aperture Indicator Post that is shown at the 6:00 position in the picture. The focusing ring configuration, colors of ADR number, etc. are not a sure indication that the lens is an original AI. Some late production non-AI lenses have all the outward physical appearances of AI lenses, but when modified they will not have the post.

AIS (Automatic Index - Shutter) Lens
	If there is a machined groove (Lens Type Signal Notch) in the base of the lens, you have an AIS, Series E, or Auto Focus (AF) lens. The purpose of the groove was to let the camera body know that aperture stop down was linear.
	Your camera can take advantage of AIS if it has this protruding pin on the camera lens mounting ring. If the pin is not on the camera body, it can't take advantage of the AIS feature, but the lens will operate as AI.

Series E Lens

Series E 35/2.5

If the lens does not have "ears", it is probably* a Series E lens or AF lens. Series E lenses have the machined groove in the lens base like the AIS lens, are manual focus, are marked as Series E and have an ADR ring. Developed for the smaller Nikon EM camera bodies as a consumer-grade lens and often denigrated for their build, Series E lenses include some of the best optical values in the Nikon line. The line included three zooms and five fixed focals; The prime lenses are: E 28mm f2.8; E 35mm f2.5; E 50mm f1.8; E 100mm f2.8; E 135mm f2.8. The Series E Zoom lenses are: E 36-72mm f3.5, E 75-150mm f3.5 and a E 70-210mm f4.0. The E series zooms are "one-touch" zooms - the same ring is used for zooming and focusing. * The word 'probably' was added after learning that some later production AIS lenses were manufactured without 'ears'. Morale : Never say never.

AF - AIS Lens

When Nikon started making autofocus (AF) bodies in response to other manufacturers, it incorporated AIS lens technology as well as an in-camera focusing drive motor. The AF - AIS lenses have the AIS groove machined in the lens mounting plate and a slotted drive screw inlet into the mounting plate at about the 5:30 position - there are no "ears" on the lens. At the 12:00 position on the mounting plate, you will see 5 electrical contacts. You will see these lenses normally marketed as AF AIS. Focusing speed was not much to brag about and Nikon later improved it.

Nikon 24-50/3.3-4.5 AF AIS

AF "D" Lens

Technology continued to improve as more functions were added to camera bodies. One improvement was the ability to meter in "3-D" mode, an improvement which allows the body (through a chip in the lens) to better assess distance from the focal plane to the object being photographed. AF"D" lenses are marked on the lens barrel. These lenses also have the slotted drive screw and 5 electrical contacts in the base plate.

Nikon 70-210/4-5.6 AFD

AF "S" Lens
So, you're still hunting for the "perfect" lens eh ? How about a "silent wave" focusing lens with an improved focusing speed over the older AF-AIS lenses? How to get this? Put a silent wave focusing motor in the lens itself to make it quiet. Note that not all AF bodies can autofocus with these lenses (see AF body chart) because they lack the circuitry to drive the lens focusing motor.

IX Lens

The Nikon IX lenses are made for the Nikon APS (Advanced Photo System) camera bodies (Pronea 6i and Pronea S) and are included here for informational purposes only since they can not be mounted to Nikon 35 mm cameras even though they may appear to be 35 mm lenses. The rear elements of these lenses extend back into the body and can not be mounted even if the 35 mm body provides true mirror lock up (MLU). The Pronea 6i and Pronea S bodies can accept and use 35 mm AF lenses, so the interoperability of this lens series is a one-way street.

And after all this, you're still not satisfied? There is talk (on today's discussion groups among the dreamers anyway) about matching the Canon "IS" (Image Stabilization) lenses - where the lens helps out with "camera shake" so your pictures don't get blurred when you try to hand-hold the camera at a shutter speed that's really too slow for the lens' focal length. Nikon hasn't got there as of this writing, but who knows? My advice is to get a tripod until then.

Along the way, there are several other Nikon lens nomenclatures that we missed - they don't affect mounting to the body, but they affect the picture and your ability to control it:

Micro - What the rest of the world refers to as macro, a lens capable of focusing at a closer range than normal.

PC - Perspective Control - Tilting the lens in relation to the film focal plane - special effects.

CRC - Close Range Correction - Lens adapted to reduce distortion when focused at macro lengths.

DC - Defocus Control - the ability to control what zones are in or out of focus, handy for portraiture for one instance.

NOCT - Nocturnal - "fast" lenses (wide aperture) with aspherical elements capable of photographs in very low light.

ED - Extra low Dispersion - Special glass that doesn't disperse the light as it enters the lens.

IF - Internal Focus - lenses that don't "grow" or shrink in length as they are focused.

Just think - if we wanted a really fast, constant aperture, stabilized, genuine all-purpose zoom lens with an internal focusing silent wave motor that offered perspective and defocus control and the ability to take really close-up pictures without distortion, we would have the following ( and it would only cost maybe $150,000.00, weigh 50+ pounds and take filters roughly the size of a really large dinner platter )

Nikon 6-800/1.2D ZOOM MICRO (1:1) NOCT PC/DC/UV/CRC AF"S" ED IS (w/Tripod Collar)