Exploring methods of two-dimensional documentation (2)

Today, digital images are records by means of a light-sensitive sensor. The more elements the sensor has, the more detailed the information. Today, professional digital camerabacks have a resolution of 2048 x 3072 pixels (6 megapixel) or more. The new Philps chip chip has 4080 x 4080 pixels (16.8 megapixel). Such digibacks can capture an image in a single shot and so can be combined with studio flash lights. 

Because information for the three basis colors Red, Green and Blue (RGB) has to be captured separately, a RGB mosaic mask in front of the sensor separates these colors, so that adjacent pixels record different parts of the spectrum. This also means that for a single pixel, no complete color information is recorded. A way around this is the so-called multi-shot mode, that moves the chip by tiny increments between subsequent shots, by means of a piezo-electric element. From 4 or even 16 subsequent shots, complete color information is composed. This is especially important when moiré effects (textile in fashion photography) have to be avoided. For an overview of sensor development and technology, see the article by Dennis P. Curtin.

Another solution is to use an even higher resolution, by scanning the picture window part by part. These parts are put together then by the software. Such scanbacks need more time, of course, to record an image, and cannot be combined with flashlight. They need either natural light or special flickerfree lamps, mostly used in the movie industry.

In order to optimize workflow and quality of our photographic recording, we tested several kinds of equipment. Previously, we had worked with conventional Nikon 24 x 36 mm and Mamiya 6 x 7 cm cameras. Since scanning negatives or slides is cost- and labour intensive, we have looked at several  high-end digital systems, in order to avoid this bottleneck.

Today (December 2004), the Nikon D70 camera offers a 2000 x 3008 pixel resolution: in combination with the newly designed lenses, it offers sufficient detail for recording small to medium-size sculptures for the purposes of our research.

A good explanation of available systems is given by John Henshall - Digital camera backs: Advice on buying a digital camera back. A test report (in German) of major high-end digibacks was published by ADF - Arbeitskreis Digitale Fotografie.