The principle upon which all camera  equipment works is traced back to artist and inventor Leonardo da Vinci who showed that all that was needed to project an image  was a small  pinhole through which light  could pass. The smaller the hole the sharper the image. The basic camera, called a "camera obscura" or pinhole camera, existed in the early 17th Century.  It took much longer for science to   find a light sensitive material to record the image.  It was not until 1826 when Joseph  Niepce from France discovered that silver  chloride could be used to make bitumen  sensitive to light that images began to be formed in a camera.

EVERY camera has these basic parts.

We begin with a light tight BOX to hold the film and carry it around from subject to subject.

This first and main part is called the body.

The second part is the shutter  which might be located in the lens (leaf shutter) or it might be located right in front of the film (focal plane shutter).

The shutter controls WHEN the light enters the camera and for how long it enters. The shutter in the lens is often faster and quieter, but makes changing the lens difficult. The shutter in front of the film allows for easy lens removal, but is often loud and slow.  A good camera will have some way of adjusting the time the shutter is open plus  there has to be some type of release for the shutter. 

The lens lets in light. The larger the  lens the more light. The lens also effects how large the image appears based on the focal  length of the lens. The aperture is located in the lens and is a set of leaf like piece of metal  that can change the size of the hole that lets  in light.   We consider the lens to be part of the shutter as we do not actually need a lens to focus an image if we have a small enough hole to let in the light.

Finally, we have the third part is film holder  inside the camera. This must have some  attachment that allows for the film to be  moved which can either be a lever or a  motor. 
 

Shutter

Controls how LONG light enters the camera. This is TIMED by the shutter speed dial, usually on top of the camera. The larger the number the SHORTER the time. A short time lets in light quickly which will stop the MOTION an object might have as it travels across the film while being exposed.

Shutter Speeds on the common camera
 

1000  -  500  -  250  -  125  -  60  -  30  -  15  -  8  -  4  -  2  -  1  -  B

Each speed is a fraction of a second - like 1/1000th of a second or 1/4 of a second. B stands for bulb and holds the shutter open as long as the shutter release is held down. This used to be attached to a long hose to a bulb held in the photographers hand, thus the name Bulb. Each shutter speed lets in half as much light at the none below it to allow for easier exposure calculations. There are two types of shutters. One is an opening in the camera lens and the other is a curtain, usually cloth or rubber, that moves accross the front of the film. The later is called a focal plain shutter. The Pentax K1000 we use in class uses a rubber curtain.

Aperture

The aperture controls how MUCH light enters the camera. This opening is inside the LENS of the camera and is adjusted by a ring on the outside of the lens.  The larger the opening the less sharp the final image will be, much like in our original pinhole camera. The larger the opening the more light that is allowed into the camera. 

Apertures on the common camera

  1.4  -  2  -  4  -  5.6  - 8  -  11  -  16 - 22  -  32

Each of these represents a fraction again, thus 2 is 1/2 and 22 is 1/22 representing the basic size of the opening in relation to the focal length of the lens.  An aperture of f2 on a telephoto lets in the same amount of light as on a 200 mm telephoto, yet the size of the opening will not be identical.

Viewfinders

 This is the opening in the back of the camera through which the  photographer looks to aim the camera.  A simple Viewfinder only camera  will simply see a small image, much like what the camera will see. In a  Reflex camera where actual light from a lens on the camera is being viewed  on a piece of ground glass a focus aid may be seen like the one at the left.  This is typical of a 35mm camera viewfinder. The space between the outer  circle and the center circle will have a fuzzy, textured look when the photo is out of focus. As the image sharpens the two circles blend into the background. The center circle is a RANGE FINDER type focus. Here the   image is cut in half. When the image in the top half aligns with the image in the bottom half the image is in focus. The rangefinder type of focus aid works better under low light conditions. 

Film Advance

Though this is not really a camera control it still is an important part of the camera. Located on the body of the camera this is usually a lever at the top right corner in the cluster of controls that usually includes shutter speed dial, shutter release, counter and film advance. On some cameras the film advance is fully automatic using an electric motor.  Often this film advance lever does more than just advance the film. On some cameras this lever when pulled out part way turns on the light meter. The film advance usually is part of the mechanism that cocks the shutter by pulling the curtain back to the right side of the camera. This same turning of the lever also advances the film counter in most cameras.