When the auto-focus was starting to make its mark, Nikon took a firm stand and did not alter its mount unlike some of its competitors. This has been a big help for Nikon users till date but is also a big cause of confusion. All of the different lens types which are available now and abbreviations being used might be overwhelming for a user. First and foremost, most of the Nikon lenses are called Nikkors. There are also some lenses which are called Nikon itself. The names are frequently interchanged by users. No confusion there. Both Nikkors and Nikon lenses are made by Nikon (except for few occasional outsourced versions like the 35-70 kit lens of Nikon FM10). Some diehard Nikon fans wince at the mix-up of the names but the fact remains.

The old lenses which are not in production are called ‘legacy’ lenses by Nikon. A lot of them can still be used with the present-day DSLRs.There is a huge market out there for used Nikon lenses. Further reading on buying used lenses – Buying a used lens

Non-AI / Pre-AI
Nikon has been producing lenses since the early 20th century. In fact it even made some lenses for Canon in the initial days. The lenses produced before AI system was invented are now called Non-AI or Pre-AI lenses. Logical! Is it not? All Non-AI or Pre-AI lenses have a letter after the word ‘Nikkor’, indicating the number of elements in the optical formula. Pre-AI lenses are not compatible with many of the present-day DSLRs. Factory converted and after-market AI converted lenses exist which can be used though.

AI Lenses
Nikon’s first change in lens mount happened in 1977, when Nikon came out with the AI lenses. AI stands for “Automatic Maximum Aperture Indexing” system. This is the mechanical system for coupling the lens to the camera’s exposure system. The camera is given the information about the maximum aperture of the lens which helps in exposure calculation. These lenses have a ridge that touches a feeler near the lens mount on the camera body. This simple system is what conveys the information.

AI lenses are manual focus, and can be used on any Nikon DSLR with a few exceptions. In general, the most of higher-end camera bodies will be able to meter through the AI lenses. The prosumer and consumer level bodies can accept an AI Nikkors, but the exposure will need to be determined using other methods.

AI-S Lenses
Nikon then introduced the AI-S version. People are divided on what this ‘S’ indicates but some photographers say that this is short for ‘Aperture Indexing Shutter’ system.  These AI-S lenses, which came later, allowed for automatic aperture control. This enabled more precise aperture control than the earlier versions. The movement of the little ‘feeler’ lever that closes the aperture and how far the aperture closes got standardized with the AI-S lenses. The aperture can be controlled by camera. (Modern DSLRs which support AI or AI-S lenses, however, do not differentiate between the two). It is easy to identify an AI-S lens by looking at its mount and checking for a small depression.

AI-S Nikon Series E lenses
These were made for the compact Nikon EM introduced in 1979, starting the use of plastics. Most of them were regarded as cheaper versions of the more expensive models except for a couple of lenses which became quite popular. These also did not have any CPU.

AI-P lens
These are manual lenses that have a CPU (basically a computer) built into them. The CPU is used to transfer metering data from the lens to the camera. These are also quite popular. The pancake lens from Nikon- Nikkor 45mm f/2.8 P is a well known normal lens (Normal Lens) from its time.

AF or Auto focus lenses
These were introduced in 1986 by Nikon. These were AI-S lenses with a built-in CPU and screw motor for AF operation.

AF-D
AF-D lenses were introduced in 1992. These are AF Nikon lenses but with a CPU that also relays Distance information to the camera, most useful for ultra-precise TTL flash and 3D Matrix metering. These had a dedicated aperture ring which unfortunately disappeared in the G versions of these lenses. The auto-focus happened through the AF screw in the camera body.

AF Nikkor lenses use a mechanical coupling between the lens and the camera body. On several Nikon DSLR camera bodies, the focus motor is in the camera and a screw turns the focusing gears inside the lens. Knowing this AF screw is important. Consumer-level inexpensive Nikon digital SLR cameras are designed without built-in focus motors, which allow them to be smaller and lighter than the larger, more professional models. These consumer DSLRs that do not incorporate a built-in focus motor, therefore, need special lenses that have built-in motors. These are the AF-S lenses. More about these lenses will come shortly.

In order to manually focus an AF lens on a present-day DSLR camera, one has to switch to manual mode by moving the AF switch from AF to M. This retracts the ‘AF screw’ so it’s possible to turn the focus ring freely. The models that don’t have the built-in motor do not have this AF-screw and so on those cameras, AF lenses must always be focused manually. Metering modes are not affected (Metering Modes). On cameras without a focus motor or when the camera is set to manual focus, the autofocus system in the camera will still tell you if the image is in focus or not with the focus confirmation dot in the lower corner of the viewfinder. More on focusing modes – (Staying Focused)

AF-I Lenses
Introduced in 1992, the AF-I lenses use an integrated focusing motor for fast autofocus operation. These were Nikon’s first lenses to offer the now popular M/A focusing mode. AF-I lenses initially were limited to expensive telephoto lenses. I have personally not used any of the AF-I lenses so can not comment much upon them.

AF-S Lenses
These have the focusing motor built into the lens. They can be used on any current Nikon camera body, whether the body has a focus motor or not. These lenses are capable of auto-focusing on all of the present-day DSLRs. The motor is marketed as being an ultrasonic ‘Silent Wave’ motor. In Nikon’s words- this enables high-speed autofocusing that’s extremely accurate and super quiet. If you are buying an inexpensive consumer model from Nikon, the camera body will not have a built in motor but the lens will. The ubiquitous 18-55mm Nikkor lens for DX bodies as an AF-S model.

R-UW
These were special lenses made for Nikonos series (under-water cameras). They feature an extra external bayonet and are incompatible with most present-day cameras. I have not included any other Nikonos lenses in this list except these since one of my friends happened to pick a wide angle lens at a cheap price and is unable to use it with his DSLR.

‘G’ type lenses are also quite popular now. These are similar to the ‘D’ lenses but lack the aperture ring. The aperture is controlled directly by the camera. The lack of an aperture control ring is perhaps the easiest way that you can tell if a lens is a G-Type or not.

AF-P
These use a “Pulse” motor or “Stepping” autofocus motor and are even quieter and smoother to autofocus than an AF-S lens. The quiet function is marketed as making these lenses ideal when shooting video with a DSLR. The caveat is that most camera bodies are not compatible with these lenses. Nikon also advises firmware up-gradation for some bodies which can then be used with these lenses. These lenses have also done away with the VR switch from the lens body. This is now controlled by the camera.

Z
This is Nikon’s entry into the world of mirror-less with a more mature approach.  The mount is different from the Nikon’s F mount. FTZ adapter is available to use some of the F-mount lenses on this new mount.

E-Type Nikkor Lenses
Some of the newer lenses now incorporate an electromagnetic aperture mechanism in the lens barrel. This is said to provide highly accurate electronic aperture blade control when using auto exposure during continuous shooting, especially when shooting at high frame rates. This is said to be an improvement from the G or D type lenses, where the aperture blades are operated mechanically. Older digital SLR camera bodies as well as film SLRs can not use E type lenses. These new E-type lenses are CPU controlled, AF-S, and should not be confused with the inexpensive MF Series-E lenses from the 1980’s.

In the vast sea of letters, there are still a few more being used by Nikon.
‘VR’ indicates vibration reduction or optical stabilization used by these lenses.
‘N’ or Nano crystal coat tells us about the new kind of lens coating to improve microcontrast.
‘DX’ are lenses that are meant to be used only with APS-C sensor based cameras. On full-frame cameras, the image circle size is not enough to cover the full sensor. (Full Frame or Crop Sensor?)
‘ED’ are special elements used inside the lens. These are high-quality glass elements with special coatings that improve the overall optical quality of the lenses by reducing chromatic aberrations.
‘DC’ – Defocus Control lenses allow controlling the bokeh, which is great for portraits. These are not soft-focus lenses as they are commonly misunderstood but very sharp lenses with additional control over the blurring of the out of focus areas.
‘Micro’ is the term used by Nikon for its macro lenses. Interestingly some of the Nikkor micro lenses do not go to 1:1 which is considered the minimum requirement for a true macro lens. What it means is that the lens is capable of photographing objects at the same size as that of the film/sensor. My favorite micro (macro) lens does only 1:2 (Micro Nikkor 105mm f/2.8 AI-s)
‘1 Nikkor’ or ‘CS’ are lenses for the old mirrorless Nikon system and not for DSLRs.

Apart from the above, the lenses have also used terminologies like closed range correction (CRC), rear-focus (RF), perspective control (PC-E) and various other terms for indicating special functions or the coatings and glasses used. Get in touch with me if you want to know something more about any of these letters used in the naming of Nikon lenses. Use this article only for information.

 

(Nikon also manufactures lenses for medical use and those can sometimes confuse camera users. One of the friends, an ophthalmologist, uses a Nikon 20D lens for indirect ophthalmoscopy. That’s a simple plano-convex lens of 20 D power and can not be mounted on any camera. )

 

If you are interested in knowing the exact lens types that can be used with a particular camera body, go through the last few pages of the user’s manual. All Nikon camera manuals provide a table of compatible Nikkor lenses.  If you have lost your camera’s user manual, download one from Nikon’s official website. Do read the complete details before choosing an old lens. Some of them may be compatible but restricted in the functionality provided. Do not depend on online compatibility charts available on various websites and forums. I have come across various compatibility errors, some of which can actually end up harming the camera so refer to the user’s manual or Nikon’s website.

 

I will not be able to write a similar article for Canon since I do not have as much information as I have for Nikon. Sorry folks! I have been a Nikon user for most of my photography period. I’ll, however, request some of my colleagues to provide me more information about Canon lenses and then maybe someday, I’ll remove this part from the article and instead publish another article dedicated to Canon lenses. As I always say, Canon lenses are very nice but it just so happens that I use Nikon. More on Nikon-Canon debate – Nikon or Canon?

 

Further Reading:
Evolution of Nikkors (Nomenclature)
Nikon CLS and SU-800