Mastering the Nikon D300

2.6. Where's the Circle?

You can't see any indication of a circle in the viewfinder, so you'll have to imagine one.

Here's how (Figure 3A): Locate your current AF sensor in the middle of your viewfinder. The length of the little rectangle you see is about 2.5mm (.10 inch) in size. If you imagine about three of these little rectangles side-by-side, that's about the same size as the default 8mm circle, which at .32 inches is about 1/3 of an inch. The 13mm maximum size circle, at .51 inches, is about 1/2 inch wide.

Figure 2-3. Close up: Metering selector set to Center-weighted

Primarily, just remember that the center area of the viewfinder provides ...