What is the metal fork on top of an older Nikon lens for?
Asked 3/8/2013
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I have an older Nikon lens with two small metal tabs/forks on the top of the aperture ring. What are they used for, and which Nikon cameras needed them?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
11
That's the metering fork, that was used to send information about the aperture setting from the lens to the camera on older camera models. The camera would have a pin that fits in the fork, so that turning the aperture ring moves the pin.
You can see some images of that at Useful Info: Nikon Lenses.
Originally by user149. Source · Licensed CC BY-SA 4.0
user149
13y ago
0
Generated from our catalog & community — verify before relying on it.
Those metal tabs are the Nikon aperture coupling fork, often called the “metering fork” or “rabbit ears.” On older Nikon film cameras, a pin on the camera body fit into that fork so the camera could mechanically detect the aperture setting as you turned the aperture ring.
This was used on pre-AI Nikon bodies, including cameras such as the Nikon F with FTn meter and early Nikkormats. Later Nikon cameras introduced AI coupling, which used a notch in the aperture ring instead, so the fork was no longer required for newer bodies. Many lenses kept the fork for a while for backward compatibility.
So in short: it’s there to mechanically communicate aperture information from the lens to certain older Nikon camera bodies.
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