Digital rangefinders

A rangefinder is a user-operated optical mechanism to measure subject distance once widely used on film cameras. Most digital cameras measure subject distance automatically using electro-optical techniques, but it is not customary to say that they have a 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 R-D1 and later R-D1s use Leica M-mount lenses, or earlier Leica screw mount lenses with an adapter. Leica released its first digital rangefinder camera, the Leica M8, in 2006. 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. The viewfinder of a rangefinder camera is necessarily offset from the taking lens, so that the image shown is not exactly what will be recorded on the film; this parallax error is negligible at large subject distances, but increases as the distance decreases. More advanced rangefinder cameras project into the viewfinder a brightline frame that moves as the lens is focused, correcting parallax error down to the minimum distance at which the rangefinder functions. The angle of view of a given lens also changes with distance, and the brightline frames in the finders of a few cameras automatically adjust for this as well. For extreme close-up photography, the rangefinder camera is awkward to use, as the viewfinder no longer points at the subject. In contrast, the viewfinder pathway of an SLR transmits an image directly "through the lens". This eliminates parallax errors at any subject distance, thus allowing for macro photography. It also removes the need to have separa e viewfinders for different lens focal lengths. In particular, this allows for extreme telephoto lenses which would otherwise be very hard to focus and compose with a rangefinder. Furthermore, the through-the-lens view allows the viewfinder to directly display the depth of field for a given aperture, which is not possible with a rangefinder design. To compensate for this, rangefinder users often use zone focusing, which is especially applicable to the rapid-fire approach to street photography. The rangefinder design does not lend itself to zoom lenses, which have a continuously variable field of view. The only true zoom lens for rangefinder cameras is the Contax G2 Carl Zeiss 35Ц70mm Vario-Sonnar T* Lens with built-in zoom viewfinder.[2] Very few lenses, such as the Konica M-Hexanon Dual or Leica Tri-Elmar, let the user select among two or three focal lengths; the viewfinder must be designed to work with all focal lengths of any lens used. On a technical level, the rangefinder may become misaligned, leading to incorrect focusing, a problem absent from SLRs. Nonetheless rangefinder cameras have advantages over SLRs for certain applications. Since there is no moving mirror, as used in SLRs, there is no momentary blackout of the subject being photographed. The camera is therefore often quieter, particularly with leaf shutters, and usually smaller and less obtrusive. These qualities make rangefinders more attractive for theater photography, some portrait photography, action-grabbing candid shots and street photography, and any demanding application where portability matters. The lack of a mirror allows the rear element of lenses to project deep into the camera body, making high-quality wide-angle lenses easier to design. The Voigtlander 12mm lens was the widest-angle rectilinear lens in general production for a long time, with a 121 degree angle of view; only recently have comparable SLR lenses entered the market.