[Don Hoey]

A little bit of history to start with by way of explanation.
When Nikon upgraded their lens range to AI ( Auto Indexing ) one of the changes to the design was to add an EE Servo Coupling Post. This was added to AI lenses to allow for electronic control, by way of a servo motor, of the lens aperture. This was achievable when using the DS-12 Electronic Aperture Control attatchment on the all mechanical Nikon F2AS.

With the advent of autofocus and advanced electronics in cameras, the option to control lens aperture electronically was taken up. For this electronic control to work, the lens had to be set to minimum aperture, and a means of signalling was required. Nikon took advantage of the EE servo post to solve the problem as it could contact a switch on the lens mount perifery. First used on the F401 it was used on a number of film cameras in particular the F80.

The F80 is relevant as it provided the chassis for the D100 and so it was carried over to that, and subsequently the D70, D50, D80 and in slightly modified form to the D40. As the Fuji S2Pro and S3Pro were based on the D80 chassis it found its way there too.

So what does it all mean.

1) On D type lenses which have a manual aperture control option on the lens this must be set to the minimum for the EE servo post to contact the switch. Unless that contact is made there is no metering and the camera will not function even in manual mode. All changes to the aperture are made electronicaly by way of the mode dial.

2) Although AI lenses have an EE servo post that could be made to contact the switch at minimum aperture, no metering is available as they do not contain a chip to advise the camera of maximum aperture. Hence no metering is available with AI/AIS lenses. For that you have to move to the D1, D2, D3, D200, D300 means of lens communication.

3) Because of the switch proximity to the lens flange, pre AI lenses will not attatch without destroying the switch unless material is removed from the lens aperture setting collar to clear the camera body and the switch.

Images attatched.

1) Explanitory image of the difference between D type and G type A/F lenses.
2) Explanitory image of the difference between Pre AI and AI/AIS lenses.
3) Image of the camera mount to indicate the switch location.
4) Another explanitory of the switch.

Episode 2 covering D1, D2, D3, D200, D300, Fuji S5Pro hopefully tomorrow.

Don