Using old Nikkor lenses on Digital Nikons
by David Barth, 3 December 2008
The venerable Nikon single lens reflex (SLR) mount is legendary in that it has not changed since it was introduced in
1959 on the Nikon F, Nikon's first SLR camera.
Changes have been made over the years to the way the lens couples to the metering system on the camera body, and the
initial discussion briefly describes the types of couplings used, because it is the lens characteristics and f-stop
setting that need to be transmitted to the camera body to provide exposure control.
Non-Automatic Indexing (NAI)
This is a Non-Autofocus, Non-Automatic Indexing Lens. Note the fork that couples with a pin that protrudes from the
bottom of a Photomic (metering) finder.
The Nikon F and Nikkormat Cameras
This shows the Nikon F Non-Automatic Indexing (NAI) meter pin that couples to a fork on a lens. As the f-stop ring
is rotated, the fork moves the pin to index the exposure meter to the f-stop setting on the lens.
The Nikon F, some F2, and most Nikkormat cameras, are Non-Automatic Indexing (NAI) cameras. They have a pin that couples
to the lens f-stop (aperture selector) ring on the rear of the lens. The lens has a
simple, metal fork that couples to a pin on the camera's light meter. This coupling allows the light meter to know the
selected f-stop of the lens, and with the speed setting on the light meter, provides an exposure indication by way
of a needle that can be seen in the viewfinder and on top of the camera.
In the case of the Nikon F, the top meter
needle display window is on the top surface of the finder. On Nikkormat cameras, the window is on the top cap, to
the left of the finder. As the f-stop ring on the lens is rotated, its coupling to the meter, via the pin on the
finder, indicates the selected lens f-stop.
Automatic Indexing (AI)
This is a Non-Autofocus, Automatic Indexing (AI) Lens. The AI feature is the raised rim on the back of the f-stop
selector ring. Note that the fork allows the lens to be used with NAI cameras.
This is another view of the Non-Autofocus, Automatic Indexing Lens AI rim.
During the early 1970's Nikon developed "automatic indexing" which changed the way the lens transmitted f-stop settings
to the camera body. This feature was applied to later F2 as well as the Nikkormat FT3, ELW, and EL2 camera bodies. The
design eliminated the pin that protruded from the finder, changing to a tab that moved around the lens mount. Instead of
using the fork on the lens, a rim on the back of the f-stop ring coupled the f-stop setting of the lens to the camera's
meter. AI lenses of this era, from the early 1970's through the mid-1970's, retained the fork to allow backward compatiblity to
the earlier, NAI cameras.
During the late 1970's, the fork on lenses was discontinued, but a small impression on the f-stop ring of the lens
indicates where one of the fork mounting holes can be drilled to attach a fork. It is not known if replacement forks
and screws are available from Nikon at this time, but I have a supply of aftermarket forks and Nikon phillips head
screws available at a reasonable price. The original screws were slotted, but they are very rare.
Note that most older, Non-AI lenses can be modified to AI by a camera repair person who can trim the rear of the f-stop
ring so that a rim allows connection to the AI tab on the camera. However, the value of old lenses may drop if they are
modified because they become less desirable to collectors.
An NAI lens should never be mounted on an AI camera body that has the tab because the rim of most lenses will
interfere with the tab, binding the f-stop ring.
Autofocus (AF) Lenses
This is an Autofocus, Automatic Indexing Lens. Note that AF lenses have pins on the back that transfer electrical
signals between the camera body and the lens.
This is an Autofocus, Automatic Indexing Lens with the indentation for attaching old-style, NAI fork.
In the late 1990s, Nikon introduced "G" lenses that did not have an f-stop ring. Instead, the lens had a small computer
chip that indicated the internal f-stop through electrical contacts on the rear of the lens. These lenses can be mounted
to older cameras, but there is no transmission of the f-stop setting to the camera. G lenses are autofocus. Nikon
continued to manufacture lenses with AI rims to enable backward compatibility to older cameras.
This is a Silent Wave Autofocus (AF-S), Automatic Indexing Lens.
This is a Silent Wave, Autofocus, Automatic Indexing Lens with indentation for attaching old-style fork.
Original AF Nikon lenses use a motor inside the camera body coupled to the lens to focus it. AF-S lenses have a
motor inside the lens that focuses it. Focus information is transmitted from the camera body to the
lens through electrical contacts.
AF-S lenses are autofocus, as the "AF" indicates, and automatic focusing is accomplished through a focusing motor
inside the lens, indicated by the "S." These lenses are similar to G lenses except that they often have the f-stop
ring and rim.
Nikon Digital Cameras: D100, D70, D70S
This is a Nikon D100 Camera without the AI tab.
Nikon Digital cameras were introduced in the 1990's, continuing with the lens mount as it was in 1959. The D100, D70,
and D70S bodies do not have an AI tab on the side of the lens mount, so they can not meter with lenses that do not have
a computer chip inside. These cameras must be operated in manual mode where the f-stop and speed setting is manually
entered into the camera. The advantage of digital cameras is that the result of an exposure can be viewed immediately,
and the f-stop and/or speed can be adjusted if the exposure is not correct. An external light meter can be helpful. I
have shot many photos through old, 1960's era lenses mounted on a D100 digital Nikon with excellent
The Nikon D200
This is a Nikon D200 Camera with AI tab.
This is a Nikon D200 Camera with AI tab.
The Nikon D200 has the AI tab beside the lens mount, allowing AI lenses to meter. The D200 also allows
lens characteristics, such as minimum f-stop, to be entered into the camera to aid in the use of older lenses. Most
Non-AI lenses cannot be mounted on the D200 because the AI tab conflicts with the f-stop ring on the lens.
Questions regarding compatiblity
The best way to approach the compatiblity issue is to compare the lens characteristics to the camera.