Cameras, whether film or digital, have basic components that make up the whole. These components work together to take the photos and all of them must work to complete the process. Some parts--such as the lens, the viewfinder and the shutter button--are universal to all types of cameras, while others--such as the charge-coupled device (CCD) and built-in computer--only appear on more recent cameras.
Lens
The standard single-lens reflex-type camera, whether 35mm-style film or digital or medium-format, starts with the lens. The better the optics, the better the final photo. A lens actually is multiple lenses arranged in groups to create the focal length. A normal lens of 50 to 55mm "sees" the same way and in the same perspective your eye does. A wide-angle lens appears to push the image back and get more of it in on the periphery. A telephoto lens magnifies the image, cutting out the peripheral parts. Zoom lenses change the focal length by moving the lens elements back and forth. Lenses also have focusing rings and aperture rings.
Film Compartment
The film compartment is light tight and holds a roll or cartridge of film on one side, stretches the film across the shutter curtain and a pressure plate and is taken up by a spool on the other side of the camera. In most medium-format cameras, this is housed in a separate film back that can be removed mid-roll when a dark slide is inserted to prevent film exposure. The pressure plate holds the film flat against a frame in which the shutter curtain is housed.
CCD
Instead of a film compartment, a digital camera has a CCD that captures the digital image and a memory card on which this digital information is stored. The CCD sits where the shutter curtain used to reside, just behind the flip-up mirror behind the lens. When the shutter button is depressed, the mirror flips up and the CCD captures the image or the shutter curtain opens and closes to expose the film.
Mirror and Pentaprism
The mirror behind the lens is used to convey the image upward through a ground-glass focusing screen to a pentaprism in 35mm-style cameras or to just the focusing screen for waist-level viewfinders found on medium-format cameras. The mirror is set on springs connected to the shutter release so it flips up when the photo is exposed and flips back down when the exposure is complete. The pentaprism reverses the image left to right and up to down so you see the corrected image through the viewfinder.
Other Parts
Manual cameras have film wind knobs, usually on the top at the right. Some film cameras have auto film winders. Both film and digital cameras have shutter speed dials so you can select the exposure length. Film cameras have a film speed dial to adjust for different types of film to allow correct meter readings. Other film cameras read the film speed automatically from the film cartridge. Digital cameras allow you to simulate ISO film speed, usually on a menu, so you can adjust for different lighting conditions.
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