article no 02> HISTORY

HISTORY

Having a general understanding on the history of SLRs is useful. And also sometimes it'll be very interesting. Anyone who is interested in this topic.., he or she can follow the wiki link below and learn more.  History of thesingle-lens reflex camera

When we talk about this topic, we have to go through some new or untouched terms.., we can clear those later. For now., let’s have a quick look on those old ones.                         

Prior to the development of SLRs, all cameras with viewfinders had two optical light paths: one path through the lens to the film, and another path positioned above (TLR or twin-lens reflex) or to the side (rangefinder). (Let’s talk about these two later.)

Because the viewfinder and the film lens cannot share the same optical path, the viewing lens is aimed to intersect with the film lens at a fixed point somewhere in front of the camera. This is not problematic for pictures taken at a middle or longer distance, but parallax causes framing errors in close-up shots. When there are two separate paths its obvious,  Moreover, focusing the lens of a fast reflex camera when it is opened to wider apertures (such as in low light or while using low-speed film) is not easy.

 TWIN-LENS-REFLEX CAMERA 

A twin-lens reflex camera (TLR) is a type of camera with two objective lenses of the same focal length. One of the lenses is the photographic objective or "taking lens" (the lens that takes the picture), while the other is used for the viewfindersystem, which is usually viewed from above at waist level.

The front of a Kinaflex twin-lens reflex camera. The focus rings of the two lenses are coupled with gears around their circumference in this simple design.

The classic Rolleiflex TLR

In addition to the objective, the viewfinder consists of a 45-degree mirror (the reason for the word reflex in the name), a matte focusing screen at the top of the camera, and a pop-up hood surrounding it. The two objectives are connected, so that the focus shown on the focusing screen will be exactly the same as on the film. However, many inexpensive "pseudo" TLRs are fixed-focus models. Most TLRs use leaf shutters with shutter speeds up to 1/500th sec with a B setting.

For practical purposes, all TLRs are film cameras, most often using 120 film, although there are many examples which used other formats. No general-purpose digital TLR cameras exist, since the heyday of TLR cameras ended long before the era of digital cameras. The main exception is the collector-oriented Rollei Mini-Digi, introduced as a rather expensive "toy" in 2004.

RANGE FINDER CAMERAS

A rangefinder camera is a camera fitted with a rangefinder: a range-finding focusing mechanism allowing the photographer to measure the subject distance and take photographs that are in sharp focus. Most varieties of rangefinder show two images of the same subject, one of which moves when a calibrated wheel is turned; when the two images coincide and fuse into one, the distance can be read off the wheel. Older, non-coupled rangefinder cameras display the focusing distance and require the photographer to transfer the value to the lens focus ring; cameras without built-in rangefinders could have an external rangefinder fitted into the accessory shoe. Earlier cameras of this type had separate viewfinder and rangefinder windows; later the rangefinder was incorporated into the viewfinder. More modern designs have rangefinders coupled to the focusing mechanism, so that the lens is focused correctly when the rangefinder images fuse; compare with the focusing screen in non-autofocus SLRs.

(A Foca camera of 1947 at theMusée des Arts et Métiers in Paris.)

(Leica M7 rangefinder)

Digital imaging technology was applied to rangefinder cameras for the first time in 2004, with the introduction of the Epson R-D1, the first ever digital rangefinder camera. The RD-1 was a collaboration between Epson and Cosina.

The M8 and R-D1 are expensive compared to more common digital SLRs, and lack several features that are common with modern digital cameras, such as no real telephoto lenses available beyond 135mm focal length, very limited macro ability, live preview, movie recording, and face detection.