Deciding on a Digital SLR Camera Viewfinder
The digital single-lens reflex (SLR) camera’s viewfinder shows you (more or less) the exact image the sensor sees. The SLR viewfinder shows the subject by using an image bounced off mirrors. With an SLR viewfinder, when you take the picture, the mirror moves out of the way to expose the sensor.
SLR viewfinders use a mirror to bounce light upward, where it then reflects off a series of surfaces until the final image appears through an optical window (as shown in this figure).
SLR viewfinders come in two basic types:
Series of mirrors: Less-expensive cameras use this type of viewfinder, in which the light reflects off separate mirrors.
Solid glass prism: More costly models use this type of viewfinder. It provides a brighter, higher-contrast image that looks better and is easier to use for viewing and focusing.