What does nikon ai s mean

So the light meter needs to take into account the difference between the aperture of the lens wide open and the aperture setting that will be used to take the shot. Which gets us to Nikon uses the name "Nikkor" for its lenses. The lenses that Nikon used on its F-mount SLR cameras between and have a little fork or "rabbit ears" on the aperture ring. The camera has a pin that rests between the tines of the fork so it can keep track of the position of the aperture ring.

When mounting a lens, obviously the pin had to be inserted in the fork and it was also necessary to turn the aperture ring all the way in both directions so the camera could learn the maximum aperture. The newest cameras that work like this are now more than 35 years old, so this meter coupling system is very, very obsolete. However, entry-level digital SLRs DSLRs such as the D3xxx and D5xxx series can mount these lenses just fine, although those cameras then operate without their light meter.

These lenses also work with many non-Nikon cameras through an adapter. When Nikon introduced the AI system, the company would convert older lenses to the new system for a modest price.

There are still a few places that perform this conversion with different levels of finesse, but if you have a nice unconverted non-AI F-mount lens, it's probably worth more in its original state.

In , Nikon came up with a new way to couple the aperture ring to the camera's light meter: Auto Indexing or AI. AI lenses have a ridge that catches a feeler on a ring surrounding the lens mount on the camera.

Mounting a non-AI lens may bend or break the feeler. AI lenses also have a mechanical system to indicate their maximum aperture to the camera, so now you just mount the lens and you can start shooting, the light meter has all the information that it needs.

AI lenses also have a second, smaller row of aperture numbers, allowing the photographer to see the selected aperture through the viewfinder. In order to let enough light fall on the aperture numbers, the rabbit ears now have a little hole on each side. The rabbit ears are no longer used, but for a long time Nikon kept including them on newer lenses for backward compatibility with older cameras.

It's not clear what the S stands for. The big difference between AI and AI-S is that the relationship between how much the camera moves the little lever that closes the aperture and how far the aperture closes is now standardized. This means the camera can control the aperture.

Before AI-S, automatic exposure meant that the photographer selected the aperture, and the camera would measure the light and select an appropriate shutter speed. Aperture priority or A on the mode dial. With AI-S lenses, shutter priority S on the mode dial is also possible, where the photographer selects the shutter time and the camera the aperture, or the camera selects both program or P mode.

Ironically, even though modern cameras still use that same system with modern lenses, they 'll only work in A or M manual mode with AI and AI-S lenses, not S or P mode. This also means that modern cameras don't care about the difference between AI and AI-S: since you control the aperture through the aperture ring on the lens, they work exactly the same. However, lower-end cameras such as the D3xxx and D5xxx don't have the aperture feeler so you lose light metering.

On the D7xxx and higher, you can use these lenses in A and M modes with light metering, but modern cameras lack the mechanism to determine the maximum aperture of these lenses, so you have to go into the menu and enter the focal length and maximum aperture under the "non-CPU lens" settings.

The aperture selected with the aperture ring then shows up in the viewfinder and LCD display s as well as in the EXIF data, along with the focal length.

This helps determining the depth of field through the matching colored lines that indicate how far before and after the distance the focus ring is set to sharpness extends. On AI-S lenses, the highest aperture value is in orange. In , Nikon introduced autofocus AF lenses. This works though a little screwdriver that sticks out of the camera, which connects to a screw in the lens that is connected to the focus ring.

With this, a motor in the camera can adjust the focus. The camera uses a number of focus sensors to determine whether different parts of the image are in focus and turns the screw accordingly. The camera communicates with the CPU in the lens electronically and learns the focal length and minimum aperture of the lens that way.

This allows autofocus cameras to do their through the lens light metering and use S and P as well as A and M. And AUTO. This retracts the screwdriver so it's possible to turn the focus ring freely.

Metering and program modes are not affected. On cameras without a focus motor or in manual focus mode, 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 viewfinder.

However, when used on an AF camera, the aperture must be set to the minimum. There's a little lock tab that keeps it there. The aperture is then set manually or automatically through the camera.

The D in model designations indicates that the lens can tell the camera the distance the focus is set to. This makes metering a little easier. At some point Nikon started building lenses that are no longer AI-S compatible. These are lenses with G in the name.

Most notably, G lenses lack an aperture ring. All G lenses are also D lenses. Although the original AF system works well and allows for smaller and lighter lenses, in Nikon introduced AF-S not to be confused with autofocus single mode, also called AF-S. AF-S lenses have their own focus motor built in. Nikon uses ultrasonic motors, which they call "silent wave". Makers of third party AF-S compatible lenses such as Tamron, Tokina and Sigma have their own names for this type of motor.

Each company also has their own name for what Nikon calls VR, vibration reduction, which moves a lens element in real time to counteract camera movement during the exposure. Unlike the aperture ring, which is now pretty much a thing of the past, they all do have a manual focus ring. A switch on the lens itself switches between autofocus and manual focus. On some mostly cheaper lenses this is a mechanical switch that disconnects the focus motor from the focus ring so the focus ring can be moved safely and easily.

On these lenses, the focus ring rotates with autofocus, and the autofocus switch switches between A and M. Selecting manual focus through the camera will turn off autofocus but not release the motor from the focus ring.

Of course moving the switch on the lens to the M position also turns off autofocus. With older Nikon lenses, typically turning the focus ring all the way to the right sets focus to infinity.

With newer lenses, this is usually not the case: they'll focus a little bit beyond infinity, so you have to use autofocus or manual focus to set the lens to infinity. All Nikon lenses until are designed to project an image that covers a piece of film or an image sensor that size.

These are 24 by 16 millimeters actually This means that a 50 mm lens on a DX camera produces the same angle of view as a 1.

Conversely, to get the same result as with a 50 mm on FX, you need a 35 mm lens on DX. So DX is said to have a "1. FX lenses work just fine on DX cameras, but the problem is that a wide angle lens isn't so wide with the effective focal length multiplied by 1.

So in Nikon introduced lenses specially made for DX cameras, taking advantage of the fact that the image that the lens has to project is 1. For the same or similar focal length or focal length range the DX version is typically cheaper than the FX version, if both are available. DX lenses are not useful on film SLRs because the corners of the image will be dark or even black. They simply switch to crop mode, where only the center area of their bigger sensor is used.

With a year history, there are of course tons of additional details, exceptions, caveats and more. But the above is pretty what you need to know about Nikon lens compatibility before you go lens shopping. Good luck! Nikon has done this smart, unlike Canon.

Canon, on the other hand, really screwed their loyal following by completely changing mounts. That means that modern Canon users no longer have access to the superlative Canon FD lenses. Way to go Canon, just one more reason why I will stick with Nikon, who I have used since What a load. The Nikon F compatibility chart is longer than most Russian novels and just as hard to keep straight.

Their system was mimicked by others. Hi, may I ask then? In short, the answer is no. The feeler around the lens mount will most likely be damaged if you try to mount a non-AI Nikkor. If you want to use the old Nikkors, you have two choices, have the aperture ring modified to AI standards or do like I did with one of my old non-AI Nikkors, do it yourself with a Dremel cutting tool.

Unless you are good with tools and know exactly where to cut given the maximum aperture of the lens, you are advised to let it be accomplished by a professional. Are there any other fully compatible lenses out there?

In answer to the digital vs. I have a couple of mint non-AI lenses purchased new in Hong Kong around or so, never used. I just got them from my father-in-law, but I'm not familiar with Nikon lens system. The aperture lever moved in a linear instead of a logarithmic travel and the FA and F4 cameras altered their Program mode shutter speed if a long lens was mounted to use a higher shutter speed.

I enjoyed this article and learned a few things too. I am a fan of older lenses probably because of their price! What's interesting about this is that they didn't start out being called "Non-AI lenses.

Later in , Nikon introduced "AI" lenses, and their predecessors strangely started being described in terms of what they were not. Imagine what it must of been like when God invented blondes. Good thing we're not calling them "Non-Brunettes.

Two of the many early lens characteristics are focal length markings in centimeters rather than MM and a solid stainless steel bayonet base rather than the five mounting screws later lenses used. About lenses with rubber focusing mounts started to appear. About multicoating started to appear, identifiable by its green color.

Please note that in at least this collector's opinion, the Original Nikon F Lenses, as introduced with the Nikon F in , belong to a special class all to themselves. They have many small characteristics which were discontinued after a short time, and make for a fascinating part of Nikon collecting.

It has a ridge in the center of it for the meter coupling pin. All NAI cameras would give incorrect exposures if the photog forgot to correctly couple the meter. Among these are the Medical and PC Nikkors, and various older longer than mm lenses.

I use the astoundingly creative terminology of " Non-Meter Coupled" to describe these lenses. Other sources use various terms, including lumping them together with the NAI lenses.

What cameras were designed for NAI lenses? The F clip on only mounts on top of the standard meterless prism. The original Photomic was not TTL. All later meters were. You can recognize Nikon's multi-coating by it's green color. In Shutter-priority and Program exposure modes this permits the camera to accurately stop down the lens to the required aperture by moving the aperture-coupling lever a known, precise, and equal distance for each increment of aperture value. This system permits the Nikon FA and the Nikon F, which was introduced a year later, to operate Shutter-priority and Program exposure modes with a far greater degree of accuracy compared with non-Ai-S lenses.

Other features found on Ai-S type Nikkor lenses but which are absent from the Ai type include the following:. On lenses with a focal length of mm or longer, the focal length indexing ridge, a flange that is located around the outside edge of the rear element, extends past the indentation in which the lens locking pin seats.

Again this is used by the FA and F cameras to detect when a telephoto lens is attached in order that the camera body will select the appropriate option in the Dual-Program exposure mode; the camera automatically switches to P-Hi high-speed Program that sets a bias toward higher shutter speeds to reduce the effects of camera shake. When lenses with a focal length shorter than mm are attached to these cameras normal Program exposure mode is selected.

On most standard and wide-angle Ai-S lenses the throw of the focusing ring in shifting focus from infinity to the minimum focus distance is reduced by about half compared with the Ai version, so that the former only require a quarter turn as opposed to a half turn for the latter. Focusing is quicker with Ai-S lenses in this range of focal lengths but as a consequence the depth-of-field markings on the lens barrel are closer to together, which makes assessing depth-of-field and the hyperfocal distance less precise.

The only two camera models actually make full use of the Ai-S lens mount: the Nikon FA and F, both of which have been out of production for many years. The F and F4 will detect that an Ai-S type lens has been mounted but both these cameras operate with Ai lenses in an identical way. All other Nikon cameras make no differentiation between the Ai and Ai-S mount.

The Ai-S lens mount represents the pinnacle of Nikons design and engineering in terms of the mechanical linkage and control of a lens diaphragm. Introduction of the AF-Nikkor lenses, which use electronics to control the lens and provide other information such as the focus distance for exposure computations have obviated the need for further development of the mechanical system.

The optical construction of most Ai lenses is either identical or very similar to the equivalent Ai-S variants, and they operate with the same functionality on compatible Nikon camera bodies. It is worth bearing this in mind when buying used equipment since, generally, the Ai-type Nikkor lenses are less expensive. Simon Stafford www. Join our Mailing List Go.