Scanner camera

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A scanner camera is a digital camera which uses no rectangular image sensor chip. Instead it uses a narrow long scan sensor bar with one row of light sensitive pixels on its surface for black&white scans or three rows instead for color scans, one pixel row for green, one for blue and one for red light. Scanning sensors may be used in professional repro cameras. Adventurous amateur tinkerers have also created their own scanning cameras. Pentacon is known as maker of scanner SLR cameras, other makers like Kigamo, Rencay, Anagramm and Betterlight focused on making scanbacks, i.e. digital backs based on scanner technology for large format frame sizes 4×5" and 9×12cm. Thus tinkerers and camera-back makers had the same concept for making large format cameras capable to shoot digitally since conventional image sensors will never reach large format size. Thus the scanner cameras have a future until the day when foil sensors in any size will be available.

The Leica S1 could serve as both, scanback and standalone scanner camera. 160 repro cameras of that type were produced bei Leitz, giving an idea about how limited the market is for scanner cameras. The maker Anagramm seems to have been vanished from the market until 2014, the others are still avalable.

The principle of the camera is that the sensor bar is moved along the image plane by a stepper motor. During its travel its light sensitive surface is exactly in the image plane and facing the lens. The step movements are interrupted for the scan of each image pixel row. Thus the sensor bar's movement is comparable with the movement of the slit of a focal plane shutter of an analog camera. But the focal plane shutter moves at fast speeds as slit whilst the sensor of a scanner camera might need more time for its travel.

The basic technologies are CCD or CMOS sensors, with pixelwise detectors realised as one long row of Bayer pattern pixel groups, or as three parallel long rows of such light detector dots, each row with filters for just one RGB base color (red, green, blue). The latter sensor type's three-row pixel arrangement makes three shots necessary per scanned line, so that each pixel of the image file will be calculated from a red, a green and a blue dot, each recorded at the same position, meaning so-called "true RGB" image pixels as result in contrast to interpolated Bayer pattern pixels. One-shot true RGB-pixels might be achieved with a row of three-color-layer technology comparable to Foveon 3-layer sensors.