|Sinar 54H digital back, Sinar P3 camera|
|This electronic camera was purchased for numismatic
photography as a successor to a Sinar 44H which was a successor in turn to
a Leica S1. The digital camera back is capable
of 5400 x 4080 resolution with a 14-bit color depth in single shot mode. For
stationary objects such as coins, piezo-electric steppers in the digital back
move the image sensor array allowing the camera to make 16 shots to expose
each image half-pixel to each color, R+G+G+B, in order to increase the color
depth, eliminate color interpolation, and double the effective
image resolution, which results in 10800 x 8160 pixels x 48 bit color. These
image files are 680 million bytes each, or over 1 gigabyte per coin.
The lighting uses a color-corrected strobe adjustable in one-tenth stop increments. Even though the lighting is from the side, it is effectively made axial with a half-silvered mirror, the mirror adjustable with three degrees of freedom as are the object, lens, and back stages. The camera's computer interface is via firewire and the its shutter and the strobe are software controlled.
A paper from the Rochester Institute of Technology describes the use of similar equipment to photograph art with a high degree of color accuracy.