Minolta RD-175
The Minolta RD-175 (also sold as the Agfa Actioncam) was one of the first digital SLR cameras. When Minolta introduced this camera in 1995 it cost around $10,000 US, inaccessible to Minolta's usual base of amature and enthusiast photographers, intended for professional business markets (including medical, insurance, and scientific) in which Minolta had made scant little inroads at the time.
Minolta engineers used a costly tricks to get acceptable colour pictures in 1.75 mega-pixel resolution:
1 - Relay optics reduce the image size from Minolta's normal 35mm SLR lenses from 36 x 24mm to 16 x 12 mm, about 1/2 or ~0.5x, (doubling the effective focal length) and reducing the e widest effective aperture to f/6.7.
2 - The light which got through the lens was split using a dichroic prism block split the image-making light into the required components for each sensor. Each part was projected onto its own CCD light-sensor.
3 - They used two green sensors, and one red/blue combination sensor, which was striped using a microscopic filter elements. This made the camera back huge compared to film SLRs. Each CCD has a resolution of 768 x 494 pixels on 6.4 x 4.8 mm chips (~3.6% area, or ~19% linear of the size of 35mm film).
4 - Then the three images were digitally integrated and interpolated out to 1,528 x 1,146 pixels, ~1.5x. The resulting 1.75 megapixel images were stored on a PCMCIA type III hard disk card.
The handling of the camera was almost like that of other autofocus SLR cameras of the time, and the lenses for this camera were simply the same as the ones for Minolta's Alpha/Dynax/Maxxum film SLR camera bodies. The picture quality, once praised, is far behind that of Konica Minolta's later digital SLRs using Sony's single-chip 6 mega-pixel resolution.
Links
- RD-175/Agfa Actioncam review by John Henshall
- Agfa Actioncam on Jarle Aasland's NikonWeb.com site
- Minolta RD-175 English 6 page PDF quick guide @ www.orphancameras.com
