Commonly employed on digital cameras, 2-stage shutter release is a shutter release, that when pressed halfway, it activates the autofocus and the light meter of the camera, setting them to achieve correct focus and exposure. Holding the release at mid-course maintains the focusing point and allows for re-composition if desired. A further press on the shutter release takes the picture.
See “A Quick Guide to Digital Cameras” in the Quick Reference section of Webopedia.
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