SLR camera

Also known as: single-lens reflex camera

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July 13, 2026

Quick Summary

A single-lens reflex (SLR) camera is a type of camera that uses a mirror system to allow the photographer to see exactly what the lens sees. This mirror reflects the image from the lens up to a focusing screen, which is viewed through the viewfinder. When the shutter button is pressed, the mirror flips up out of the way, allowing the light to hit the film or sensor. This mechanism is key to how SLR cameras achieve precise focusing and framing.1

SLRs often feature interchangeable lenses, built-in light meters for accurate exposure, and advanced electronic controls. They are distinct from twin-lens reflex cameras, which have two separate lenses—one for viewing and one for capturing the image.12

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technology of photography
The single-lens reflex
The ground-glass screen at the back of the studio, or view, camera slows down picture taking because the screen must be replaced by the film for an exposure. The single-lens reflex camera (Figure 2) has a screen, but the film remains constantly in…
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The ground-glass screen at the back of the studio, or view, camera slows down picture taking because the screen must be replaced by the film for an exposure. The single-lens reflex camera (Figure 2) has a screen, but the film remains constantly in…
Read More

viewfinder
In the single-lens reflex camera, the camera lens itself serves as the finder in conjunction with a ground-glass focusing screen to which the image is reflected by a mirror. The image is viewed on the screen through a pentaprism that corrects the lateral reversal of the image…
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In the single-lens reflex camera, the camera lens itself serves as the finder in conjunction with a ground-glass focusing screen to which the image is reflected by a mirror. The image is viewed on the screen through a pentaprism that corrects the lateral reversal of the image…
Read More