#1. "RE: Using AI lenses on D5000" In response to In response to 0 Sun 20-Sep-09 05:28 PM by gkaiseril
The AI lens was introduced in 1977. The Nikon "AI" lens is a lens that allows for the automatic setting of the maximum f Stop for Nikon camera. Earlier Non-AI lenses required the turning of the aperture ring for setting the aperture for exposure by centering the exposure needle within the brackets. AI lenses added a metering ring that the camera would allow the camera to set the f stop for the correct exposure. For both lenses the iris release lever allowed the lens's iris to close for the exposure. A Non-AI Nikkor lens.
The exposure meter will not adjust the lens's aperture for the correct exposure since there are no electronics within the lens to send lens information to the camera and to receive the signals from the metering circuitry and set the lens's aperture. You can use the 'sunny 16' rule to estimate the exposure and then chimp the shot and look at the histogram to fine tune the next exposure.
Once you stop the lens to f 5.6 or smaller, there is not enough light entering through the lens for the focus circuitry to work, detect contrast.
The lens will not auto focus since there is no focus motor within the lens and your camera does not have the in camera focus motor and screw head to turn the lens's screw driver head focus link, but you can manually focus the lens and the viewfinder's focus indicator will indicate when it thinks proper focus has been attained.
With the AI and Non-AI lenses the photographer had to manually turn the focus ring to set the desired focus.
With the original Nikon F, 1959 - 1962, one needed to use a external light meter and set the camera's f stop, shutter speed and focus prior to taking an image and then manually advance the film and wind the shutter spring with the film advance lever. One never needed to charge or replace a batter on that model.