Knew More Single Lens Reflex (2)

08 Agustus 2009

In this time, I want to share about optical components in SLR camera.

A cross-section (or 'side-view') of the optical components of a typical SLR camera shows how the light passes through the lens assembly (1), is reflected by the mirror (2) and is projected on the matte focusing screen (5). Via a condensing lens (6) and internal reflections in the roof pentaprism (7) the image appears in the eyepiece (8). When an image is taken, the mirror moves upwards from its critical 45 degree angle in the direction of the arrow, the focal plane shutter (3) opens, and the image is projected onto the film or sensor (4) in exactly the same manner as on the focusing screen.

This feature distinguishes SLRs from other cameras as the photographer sees the image composed exactly as it will be captured on the film or sensor.

Pentaprisms and penta-mirrors

Most SLRs use a roof pentaprism or penta-mirror to direct the light to the eyepiece, but there are other finder viewing capabilities, such as the waist-level finder, the interchangeable sports finders used on the Canon F1, F1n and F1; the Nikon F, F2, F3, F4 and F5; and the Pentax LX.

Another prism design was the porro prism system used in the Olympus Pen F, the Pen FT, the Pen FV half-frame 35 mm SLR cameras. This was later utilized on the Olympus EVOLT E-3x0 series, the Leica Digilux 3 and the Panasonic DMC-L1.

Lastly, a photographer can also purchase a right-angle finder which slips onto the eyepiece of most SLR's and D-SLR's and allows viewing sans a waist-level finder. There is also a finder which provides EVF remote capability.