Apple Aperture Digital Photography Fundamentals - Manual (Page 9)

Chapter 1 How Digital Cameras Capture Images 9
Digital Rangefinder
There are two classes of digital rangefinder cameras: coincident rangefinder and
point-and-shoot.
Coincident Rangefinder
Unlike DLSR cameras, the coincident rangefinder does not provide the photographer
with the ability to view the subject through the lens
. Instead, the coincident
rangefinder employs a mirror or prism that uses triangulation to unite the images seen
through the viewfinder and a secondary window to bring the subject into focus. The
photographer sees two images overlaid on top of one another in the viewfinder, and
the image is not in focus until there is a single image. As with DSLRs, most features in a
coincident rangefinder are adjustable, allowing for maximum control over the captured
image. An advantage to using a coincident rangefinder over a DSLR is that the lack of a
reflexing mirror significantly reduces camera shake. Camera shake is due to hand
movement or the vibration of the reflexing mirror found in a DSLR, and can cause
blurring of the image.
Rotating mirror/prism
Image sensor
Light-gathering window
Semitransparent
mirror
Viewfinder
Beamsplitter
semitransparent mirror
Light source
Reflective
light
Out of focus
(image overlays not aligned) In focus
(image overlays aligned)