Sony a (alpha) DSLR-A100 Operating Instructions Manual page 15

2 Keep the shutter button halfway down, and put the subject back in the original position to re-
compose the shot.
3 Press the shutter button fully down to take the picture.
• The focus-lock function will lock the exposure as well (when multi segment metering is selected
(page 58)).
• Releasing the shutter button after shooting will disengage the focus-lock. If you keep the shutter button
halfway down after shooting, you can continue shooting with the same focal point.
• If the z indicator does not light up in the viewfinder (the subject is in motion), you cannot use the focus-
lock function by pressing the shutter button halfway down. (See pages 53 and 71.)
Subjects that may require special focusing:
Using the auto focus, it is hard to focus on the following subjects. In such cases, use the focus lock shooting
feature or manual focus (page 71).
– A subject that is low in contrast, such as blue sky or a white wall.
– Two subjects at different distances overlapping in the focus frame.
– A subject that is composed of repeating patterns, such as the facade of a building.
– A subject that is very bright or glittering, such as the sun, the body of an automobile, or the surface of
water.
To measure the exact distance to the subject
The horizontal line in the illustration shows the location of the CCD* plane.
When you measure the exact distance between the camera and the subject,
refer to the position of the horizontal line.
* The CCD is the part of the camera that acts as the film.
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