Nikon D7000 manual Indexing

Chapter 3 ■ Nikon D7000 Roadmap 85

Figure 3.33

Automatic diaphragm lever

Indexing	Electronic	Lens type	Lens
cutout	contacts	signal	bayonet
		notch	mount

taking aperture is determined by the camera’s metering system (or by you when the D7000 is in Manual mode), and is communicated to the lens through the elec- tronic contacts described next. (An exception is when the aperture ring on the lens itself is unlocked and used to specify the f/stop.) However, the spring-loaded phys- ical levers are what actually push the aperture to the selected f/stop—even with advanced cameras like the D7000 or D3s. The aperture lever is also activated when you press the DOF button.

■Electronic contacts. These metal contacts pass information to matching contacts located in the camera body allowing a firm electrical connection so that exposure, distance, and other information can be exchanged between the camera and lens.

■Lens type signal notch. This is a machined groove in the lens mount, designed to tell older (non-dSLR) cameras that the aperture stops were linear. Today, this infor- mation would be conveyed electronically, except that all current lenses already have linear f/stops.

■Indexing cutout. The base of any Nikon lens made after 1977 that has an aper- ture ring includes a cutout notch that mates with a ring around the lens mount of Nikon’s advanced cameras (D200, D300/D300s, D2x/D2xs/D3/D3s/D3x/D700, and some older pro models). It tells the camera what the maximum aperture is and