Nikon D90 user manual Mode a Aperture-Priority Auto, Choose an aperture, Depth of Field

Mode A (Aperture-Priority Auto)

In aperture-priority auto, you choose the aperture to control depth of field (see below) while the camera automatically selects the shutter speed that will produce the optimal exposure. To take photographs in aperture-priority auto:

1 Rotate the mode dial to A. Mode dial

t2

Choose an aperture.

Press the shutter-release button halfway to activate the exposure meters and rotate the sub-command dial to choose the desired aperture from values between the minimum and maximum for the lens.

Sub command

dial

3Frame a photograph, focus, and shoot.

ADepth of Field

“Depth of field” is the distance to which objects behind and in front of the focus point appear to be in focus. Large apertures (low f-numbers) reduce depth of field, blurring objects behind and in front of the main subject. Small apertures (high f-numbers) increase depth of field, bringing out details in the background and foreground (note that depth of field is also influenced by other factors, such as focal length and focus distance). Short field depths are generally used in portraits to blur background details, long field depths in landscape photographs to bring the foreground and background into focus.

To preview depth of field, press and hold the depth-of-field preview button. The lens will be stopped down to the current aperture value, allowing depth of field to be previewed in the viewfinder.

Depth-of-field preview

button

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