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David Busch’s Nikon D3100 Guide to Digital SLR Photography
Figure 1.14
Metering mode
icons are (left
to right):
Matrix, Centerweighted, Spot.
4. Press OK to confirm your choice.
5. Press the information edit button to exit, or just tap the shutter release button.
■
Matrix metering. The standard metering mode; the D3100 attempts to intelligently classify your image and choose the best exposure based on readings from a
420-segment color CCD sensor that interprets light reaching the viewfinder using
a database of hundreds of thousands of patterns.
■
Center-weighted metering. The D3100 meters the entire scene, but gives the most
emphasis to the central area of the frame, measuring about 8mm.
■
Spot metering. Exposure is calculated from a smaller 3.5mm central spot, about
2.5 percent of the image area.
You’ll find a detailed description of each of these modes in Chapter 4.
Choosing Focus Modes
This section shows how to select when the D3100 calculates focus: all the time (continuously), only once when you press a control like the shutter release button (single autofocus), or manually when you rotate a focus ring on the lens.
The Nikon D3100 can focus your pictures for you, or allow you to manually focus the
image using the focus ring on the lens (I’ll help you locate this ring in Chapter 2).
Switching between automatic and manual focus is easy. You can move the AF/MF (autofocus/manual focus) or M/A-M (manual fine-tune autofocus/manual) switch on the
lens mounted on your camera.
When using autofocus, you have additional choices. The D3100 has eleven autofocus
zones that can be used to zero in on a particular subject area in your image. (See Figure
1.15.) In addition, you can select when the D3100 applies its focusing information to
your image prior to exposure.