Image Size and Format in Digital Imaging
and Film Photography
The image size recorded in a digital sensor unit (digital back) or digital camera is determined
by the size of the sensor in the camera or digital back. Sensors in Hasselblad digital cameras
or digital backs can be 36.7 36.7 mm, 33.1 44.2 mm, or 36.7 49 mm, the largest pres-
ently available for any camera, including view cameras.
All of these Hasselblad sensors are much larger than the 23 15 mm APS-C sensor used
in most professional digital SLR cameras. The Hasselblad sensors are also considerably larger
than the 24 36 mm full frame sensor found in a few digital SLR cameras. To be more spe-
cifi c, the area of the 36.7 49 mm sensor is more than 5 larger than the APS-C sensor area
and more than double that of the full frame type. The sides of the 36.7 49 mm sensor are
more than twice as long as the sides of an APS-C sensor recording a subject more than twice
as large, and about 1.5 larger than in a full frame digital camera (Figure 2-1).
Therefore, digital Hasselblad cameras offer the same advantage of recording a much
larger and sharper image in the camera as- they do in fi lm photography compared to 35 mm
or APS cameras. These larger images also offer the photographer much greater possibilities
for cropping and changing the image shape. For digital photography Hasselblad offers the
same compromise between quality and camera portability that made Hasselblad medium-
format cameras popular for critical and serious black and white and color fi lm photography
for so many years.
DIGITAL IMAGE QUALITY
The digital image is formed on the sensor in the camera or digital back by pixels that are light
sensitive to either green, blue, or red. The resolution is indicated by the total number of pix-
els, which is obtained by multiplying the number of pixels along either side of the sensor. For
example, a 39 megapixel specifi cation is obtained by multiplying the 5412 and 7212 pixels
along the image sides. Most professional digital SLR cameras have resolutions from 6 to 12
megapixels, some newer ones going as high as about 20 megapixels. Hasselblad digital backs
or cameras offer resolutions from 22 to 39 megapixels.
The number of pixels is directly related to the image quality produced in the camera. The
higher the number of pixels, the better the image quality but only if everything else is equal,
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