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Nikkor G lenses have a built-in USM motor that permits auto-focusing on bodies with or without the focus motor. They also permit changing the aperture from the aperture dial on the body. Nikkor G lenses do not have an aperture dial on the lens itself.

Nikkor D lenses do not have a built-in USM motor. They can auto-focus from bodies equipped with a focus motor. Nikkor D lenses also have an aperture dial on the lens.

Do Nikkor D lenses permit aperture adjustments from the dial on the body, or does the existence of an aperture dial mean that one must use it? The G lenses presumably have some kind of motor, in addition to the focus motor, to change aperture. If adjusting the aperture of a D lens from the body is possible, does the aperture ring move? Probably not, since it would drain a lot of energy. If the aperture is controllable from the body, does this mean a D lens does have some kind of aperture motor after all?

  • G lenses use the same mechanical coupling to control the aperture as older lenses. All they lack is a ring outside the barrel. There is no motor in the lens that moves the blades. – Blrfl Dec 29 '14 at 20:25
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All Nikon lenses (including D and G series) have a mechanical lever built into the lens that is moved by the camera body. No motor. The aperture ring is typically left locked at the highest aperture setting (say f/22) and aperture controlled by the dial on the body.

Here is the lever on my 50mm 1.4G:

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As @Blrfl said, the only difference between D and G is that the G lacks the external ring for manually changing aperture, which is rarely needed on a modern body anyway. The internals are the same for aperture.

  • Very interesting.. I see that the play (the distance moved by the lever) is very short. This hints that the aperture ring on a D-type lens does not move when the lever is manipulated by the body (since otherwise the torque required would be substantial). Is that the case? – Calaf Dec 31 '14 at 22:41
  • @Calaf No, the aperture ring remains fixed, only the aperture leaves are moved. – MikeW Jan 1 '15 at 1:23

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