You will need access to a digital camera and some type of storage or output device during the course.
This is required so that you can take some photographs on a digital camera and submit them as a print or as a digitised file. An inexpensive digital camera and a printer or 3.5 inch floppy disk would be a minimum. If you plan to purchase a digital camera, but have not yet decided what to buy, it is recommended that you delay buying a camera until you have completed Lesson 3 and commenced Lesson 4. It is also suggested that you ask your tutors advice as to which camera would best suit your needs. Access to a suitable computer is also advantageous but not essential.
If you understand conventional photography, you already understand most of the operations of a digital camera.
If a small hole is made in the wall of a dark room or, as may have been in ancient times, a tent, the action outside the room or tent would be seen, projected onto the interior wall opposite the hole, the picture being inverted left for right and upside down. This phenomenon was almost certainly known since ancient times.
This is how the earliest examples of image formation were achieved.
Light can only travel in straight lines, and it can only move around a corner or angle by reflection.
Given that light only travels in straight lines, an image is formed as follows:
Imagine a standard lamp outside a dark room. Light rays are reflected from all parts of the standard lamp in straight lines.
If there is a hole in the wall of the room, some of these light rays will pass through that hole in the wall.
Light rays coming from the top of the lamp at a downward angle relative to the floor will meet the opposite wall close to the floor inside the room. This creates an image of the top of the lamp at close to floor level.
Light rays coming from the bottom of the lamp travel at an upwards angle through the hole to meet the wall close to the ceiling on the opposite wall. This creates an image of the bottom of the lamp near the ceiling.
The hole acts to restrict the transmission of light so that only the rays which enter it at the correct angle from the subject will pass freely through and form an objective image of the lamp. As a result, the rays are "selected" by the hole. The image is both upside down and inverted left for right. Rays that could form a correctly oriented image are diverging from the lamp in opposite directions and cannot form an image.
Box rooms were known as "Camera-Obscura" or "Dark Chambers".
The camera obscura, is historically the forerunner of all modern cameras and has lent its name to them. Today it is perpetuated, in miniature, by the pinhole camera.
One of the most significant developments in photographic history is the lens. Lenses probably originated when some distant ancestor happened to notice that a rounded crystal they were holding seemed to form an image of the sun on the ground, much the same as a magnifying glass.
The first practical lens for a camera obscura was designed in 1812. The first lens specifically made for photography was produced around 1840. Lenses operate on the principle called refraction. Although light moves in straight lines, its rays can be bent (or rather turned onto a different angle), when passed through a lens.
What Happens To Make It Look Bent?
Light does not travel at the same speed through all transparent materials.
When light illuminating your pencil or knife enters the water, it changes speed (slows down). As it does so, it changes direction to a new, straight-line course.
This leads to the light being reflected from the object in the water being ‘refracted’, to a different angle before reaching your eyes.
This is what makes the pencil or knife look bent.
The principle of refraction is the basis of all lens design.
The degree to which light ‘bends’ is dependent on two factors:
- The angle the light hits the surface of the new medium which it is being passed through (e.g. Water, glass etc.).
- The type of material the light is entering.
The simplest photographic lens uses this principle to refract and focus light. This is called a "biconvex lens”, having two outwardly curving surfaces. A magnifying glass is such a lens. A ray of light entering a biconvex lens is refracted.