Views: 12
THE CAMERA
The camera is a device to capture an image on a desired medium. The basic principles between all cameras are the same. The basic parts are: lens, iris, shutter and the medium and sometimes filters. The lens gathers light from the selected image and focuses the light on to the medium.
Parts of a camera
TYPES OF CAMERAS
The Simple Camera
A simple camera consists of:
(a) A light tight box with a lens
(b) A shutter to admit light briefly to the film
(c) A film cassette (a compartment for film)
Most simple cameras have a fixed forces lens that is built in front of the camera. This is not variable and it’s only set maximum overall sharpness of the image i.e. you cannot adjust the lens to move the object closer or away from the point of focus.
Behind the lens, is a shutter consisting of movable blades or rotating disks, which protect the film from light until when it is necessary. They open when the shutter is pressed and these when light is allowed to reach or fall briefly on the film surface.
Simple cameras have a limitation, which includes;
(i) View finder error
(ii) Fixed distance of focus images not being sharp due to their cheap or poor quality lens
(iii) Enlarged photographs are generally of poor quality
Rangefinder Camera
As camera and lens technology developed and wide aperture lenses became more common, rangefinder cameras were introduced to make focusing more precise. Early rangefinders had two separate viewfinder windows, one of which is linked to the focusing mechanisms and moved right or left as the focusing ring is turned. The two separate images are brought together on a ground glass viewing screen. When vertical lines in the object being photographed meet exactly in the combined image, the object is in focus. A normal composition viewfinder is also provided. Later the viewfinder and rangefinder were combined. Many rangefinder cameras had interchangeable lenses, each lens requiring its own range- and viewfinder linkages.
Rangefinder cameras were produced in half- and full-frame 35 mm and rollfim (medium format)
Single-Lens Reflex Camera
In the single-lens reflex camera, the photographer sees the scene through the camera lens. This avoids the problem of parallax, which occurs when the viewfinder or viewing lens is separated from the taking lens. Single-lens reflex cameras have been made in severalformats including sheet film 5×7″ and 4×5″, roll film 220/120 taking 8, 10, 12 or 16 photographs on a 120 roll and twice that number of a 220 film. These correspond to 6×9, 6×7, 6×6 and 6×4.5 respectively (all dimensions in cm). However, the most common format of SLR cameras has been 35 mm and subsequently the migration to digital SLR cameras, using almost identical sized bodies and sometimes using the Same Lens Systems.
Almost all SLR cameras used a front surfaced mirror in the optical path to direct the light from the lens via a viewing screen and pentaprism to the eyepiece. At the time of exposure the mirror flipped up out of the light path before the shutter opened
Twin-Lens Reflex
Twin-lens reflex cameras used a pair of nearly identical lenses, one to form the image and one as a viewfinder.
The lenses were arranged with the viewing lens immediately above the taking lens. The viewing lens projects an image onto a viewing screen, which can be seen from above.
The advantage of a TLR was that it could be easily focused using the viewing screen and that under most circumstances the view seen in the viewing screen was identical to that recorded on film
At close distances however, parallax errors were encountered and some cameras also included an indicator to show what part of the composition would be excluded. These cameras take films that significantly smaller than 35 mm.