4.2 … control the exposure (continued)
4.2.3 Using the exposure speed to control the exposure
Contrary to „one-shot“ photography, where the exposure is defined by the time
between opening and closing of the shutter, the Seitz D3 Digital Scan Back creates the
exposure by scanning*. The read-out of data (pixels) is continuous. Hence, the exposure
is defined by the time the area of the sensor is exposed for one point in space.
For example, when using 10 vertical lines (10 TDI stages) for the scan, one pixel is
exposed 10 x at a 10 x faster exposure speed (underexposed). The sum of the 10
exposures then gives the final pixel exposure. This is how a 10 x faster image capture
can be achieved compared to scanning with just one line.
The more sensitivity is used (by using TDI stages), the longer is the equivalent
exposure. In other words, when increasing TDI stages for equal lighting conditions,
the photographer needs to close the aperture accordingly, otherwise the image will
be overexposed.
Scanning
speed
TDI Stages
Exposure
(per pixel)
=
x
Instruction Manual Seitz 6x17 Digital - version 4.05 - May 2013- © by Seitz Phototechnik AG / Switzerland www.roundshot.ch page 48
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