The main advantage of a single-lens reflex (SLR) camera over its point-and-shoot counterpart is you can control the shutter speed and aperture settings. This allows you to have more creative control over the resulting photograph. SLRs also usually have detachable lenses and the ability to use an external flash, resulting in more components than basic film cameras.
The camera's aperture is a diaphragm located in the lens of an SLR camera. It controls the width of the opening that lets light into the camera, and influences how much of the depth of a photograph is in focus. Basic SLRs have an aperture ring located close to where the lens meets the camera body. Newer SLRs have a selector dial and a digital panel that displays the aperture setting as a number, such as 4 or 5.6, for example.
The SLR camera contains a shutter that determines how long light enters the camera. It controls whether moving objects will appear sharp or blurry. Basic SLRs have a shutter speed dial on top of the camera body marked with numbers that can range from 1 to 1000, representing fractions of a second. Sometimes these cameras have a film speed, or ISO, selector embedded within the dial you can access by lifting its edges and twisting it to the desired film speed. Digital-display SLRs let you choose shutter speed and ISO with a selector dial.
Most SLR cameras have a detachable lens so you can choose between long, short, normal or zoom options. You may have to hold down a lens release button on the front of the camera body and simultaneously twist to unlock it and remove the lens. Lenses and camera bodies are marked with a small dot of a particular color to show you where to insert a different lens and twist it into the lock position.
Shutter Release Button and Film Advance Lever
The shutter release button works just like its counterpart on a point-and-shoot camera. When you press it all the way down, the camera makes an exposure. Older cameras also have a film advance lever that moves the film into place for the next exposure; you cannot make another exposure before pushing it forward. Newer SLRs automatically advance the film for you.
Many SLRs come outfitted with a flash hotshoe on top and in the center of the camera body. The hotshoe is a small area surrounded by two metal or plastic grooves with small circle sensors in the middle. These sensors help the flash and the camera communicate so you can make proper exposures with an attached flash.
Rewind Release Button and Rewinder
While newer SLRs automatically rewind film when it is done, this process is manual with an older camera. The film release button is located on the bottom of the camera body, underneath where you load the film. Once you press it, you can use the rewinder crank on top of the camera body to wind the film back into its cartridge.