Whether basic or digitized, SLR cameras have similar parts.
Film cameras vary in complexity, but single-lens reflex cameras all have the same basic structure. Newer and more expensive models may have digital panels to replace knobs and rings that would physically change settings. However, most all have manual controls and exchangeable lenses that make them an excellent choice if you want to move beyond the amateur level of photography.
Film Pressure Plate
The film pressure plate is located on the inside of the back door of the camera body. It holds the film on a flat plane so that you can properly focus the images. You should not ever touch the plate; as the film moves across it, foreign particles on the surface can cause scratches.
Shutter Curtain
You can see the shutter curtain when the camera back is open. The shutter is made of multiple "leaves" and opens for a set amount of time to let light into the camera and make an exposure. Some 35-mm shutter curtains open from left to right, while others open from top to bottom.
Viewfinder
The viewfinder is located in the center of the camera body for an SLR. An SLR's viewfinder gives an accurate representation of what will be in the photo due to the series of mirrors, called a pentaprism, that are in place to show you exactly what the lens sees.
Lens
SLR cameras usually have a detachable lens that is composed of multiple pieces of glass that focus the image. You can focus the lens by hand by turning the front ring on the lens. More advanced cameras have autofocus, which you can access by half-way tapping the shutter release button. Lenses may be fixed, meaning they use just one focal length, or may be a zoom, which allows you to choose from multiple focal lengths by turning the zoom ring.
Aperture Ring
Aperture rings are present on some models of SLR camera lenses; they are located closest to the camera body. They allow you to choose the width of the diaphragm that lets in light, which affects how much of the depth of your image is in focus. Other camera models provide aperture controls through the digital display panel, which you can access by turning a dial and choosing from number settings of f/2 to f/22, for example.
Shutter Speed Dial with ISO
SLRs may have a dial on top of the camera body that lets you select a shutter speed. Often housed within the shutter speed dial is an ISO selector that lets the camera's light meter know what speed of film you are using. Camera models with digital display panels also have a dial for shutter speed, where you pick from slow shutter speeds like 1/15 of a second to fast ones, such as 1/2000 of a second.
Shutter-Release Button
All SLRs have a shutter-release button that allows you to make the exposure. Some types are hollow in the center so you can add a cable release. This lets you make an exposure without touching and potentially moving the camera.
Film Advance Lever
Basic models of SLRs have a film advance lever that you must push to advance the film after each exposure. If you don't advance the film, the shutter-release button does not function. The lever stops moving when you have reached the end of the film.
Rewind Release Button and Rewind Crank
Some 35-mm cameras must be rewound manually, and make use of a rewind release button on the underside of the camera body. Once you press it, you can rewind the film with the rewinder crank, located on top of the camera body.
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