Pinhole Camera Basics

• You can make a camera from any object that can be made impervious to light: a box, a room, or even a car with taped-up windows. The principle involved is that when light passes through a small enough opening, it creates an image that can be focused on a surface placed opposite the opening. Because of the angle of the light traveling through the hole, the image is upside-down and laterally reversed on the surface. Many photographic artists today still use pinhole cameras for creative exploration.
  
  

Lenses

• Because the hole in a pinhole camera is so small, it generally takes minutes or even hours to make an exposure. This is why lenses were introduced into the evolution of the camera. Enlarging the size of the opening to the camera body reduces exposure time, but it defocuses the image. A modern photographic convex lens focuses the image by refracting light rays so that they converge onto the film plane or sensor. Lenses consist of multiple components that perform this complex task.
  
  

Image Capture

• The camera captures the image through the use of film or, with a digital camera, a silicon sensor. Modern film has a base of plastic and is coated with a light-sensitive silver compound. When light strikes the film, these areas turn dark, while the areas that do not receive light remain clear. Thus the film appears as an inverse of values, creating a negative. A digital camera's sensor is composed of millions of "photosites" that resemble a checkerboard. Each photosite captures electrons as light hits it, storing the information as a string of numbers. A computer reassembles these numbers to create a photographic image from the information.
  
  

Additional Controls

• Some cameras provide manual controls to help you decide on the appearance of the photo. Lenses contain a diaphragm that controls the width of the opening that lets light pass through to the film or sensor. This is called the aperture control. Aperture affects how much of the depth of the image is in focus. Shutter speed controls the amount of time light is allowed to pass through the camera to the film or sensor. It allows you to either freeze motion or make it blur. ISO refers to how sensitive to light the film or sensor is. A high ISO number setting on a digital camera or a high ISO rating on film allows you to make sharper images in low-light conditions.