Camera types
Contents
The following sections should be moved to individual pages
View Camera
Rangefinder
Rangefinder cameras are those that focus using some sort of coincident-viewing distance-determination mechanism. The most common form, as used in cameras like the Leica and other classic small 35mm cameras, is to use a prism and mirror arrangement between two viewing windows. Small adjustments in the angles of the prisms will align two superimposed images -- when the images are aligned the distance can be determined accurately by a simple mechanical cam. Such rangefinders have been used in 35mm cameras for many years and also in larger-format cameras such as "folder" medium format cameras, "Texas Leicas" like the Mamiya 7 and even some early polaroid cameras.
Other styles of rangefinder do exist, such as the electronic variety found in the Contax G1-G2 cameras. In general, "rangefinder" focusing is often used to describe any focusing mechanism that doesn't view directly through the taking lens (or an identical copy of that lens, as in Twin Lens Reflex cameras).
Pocket and Point & Shoot cameras
Single Lens Reflex
With a single lens reflex camera, the viewfinder image is rendered by the taking lens. In the light path is a mirror with 45° angle, that reflects the viewfinder image upwards onto a ground glass screen.
To take the image, this mirror is flipped out of the light path between lens and film plane, before the shutter opens.
The advantage of this system is, that there is no parallax error as in a rangefinder or twin lens reflex camera. You always see the image of the taking lens and do not need any additional viewfinders for different focal lengths. This makes the use very comfortable.
The slap of the mirror is the main problem of the SLR design, because it causes vibrations and camera shake, which makes it difficult to hand-hold an SLR at slower shutter speeds.
In many vintage SLRs (and few modern ones with interchangeable finders), the image on the ground glass is directly seen from above (waist-level finder) - it's upright, but reversed (left and right). In most modern SLRs, the ground-glass image is seen through a prism that resides on top of the ground glass screen. The view through the prism gives you an upright, unreversed viewfinder image (eye-level finder).
Twin Lens Reflex
Twin Lens Reflex (TLR) cameras are "two-eyed" cameras such as the classic Rolleiflex. They consist of a ground glass on the top and two lenses on the front.
The scene viewed by the top lens (the viewing lens) is reflected by a mirror onto the ground glass. The image seen on the ground glass is back to front (left is right, right is left) which can take some getting used to.
The bottom lens (the taking lens) exposes the film. This means that, unlike Single Lens Reflex cameras, the viewed image is not exactly the same as the image recorded on the film - the difference being the distance between the centre of the viewing lens and the centre of the taking lens. This discrepancy is known as parallax error, which can be corrected by lifting the camera until the taking lens is as high as the viewing lens was when the image was composed.
Well-known TLR manufacturers are Rollei, Yashica and Seagull. Popular and beautiful TLRs were also made by Japanese companies such as Minolta prior to the 1970's.
