Hasselblad Digital Camera, Manual

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Creating the Digital Image
99
advantage of digital imaging compared to fi lm photography is the possibility of seeing
instantly whether the exposure is correct. You need not develop a fi lm or make a test expo-
sure on instant fi lm. Evaluating the histogram that appears on the screen is an excellent way
to determine exposure. There are other ways the camera can communicate with you and tell
you whether the exposure is good, satisfactory, or unusable. Hasselblad offers various options
to do that. They depend on the camera model or the type of digital back but the histogram
evaluation works with all cameras and digital backs.
First you have the image that appears on the preview screen immediately after the expo-
sure. While the larger preview screen on the H3DII cameras helps this evaluation, you must
realize that the image on the preview screen gives you only some idea of the exposure and
should never be a fi nal answer as the brightness of the image can be changed and the image
is diffi cult to evaluate in bright light. Never use the image on the screen to evaluate exposure.
The H3D camera models can be programmed so you hear different sound signals immediately
after the picture is made telling you whether exposure is good or whether the images are
under or over exposed. This is done with the Sound Menu option.
The Histogram Evaluation
A Hasselblad digital imaging exposure can be evaluated from a histogram immediately after
the image is recorded. With action shots the image you recorded may be the fi nal image. In
other cases you have the opportunity to make adjustments in the lens settings if the histo-
gram does not look completely satisfactory and then see how the change affected the expo-
sure on the new histogram. You can eliminate images with unsatisfactory histogram readings
immediately. The histogram offers a much more precise image evaluation than the image you
see on the display screen.
With Hasselblad digital cameras and digital backs, the histogram always appears on
the Preview screen. On H camera models you can also see it on the grip LCD after you pro-
gram custom option SHOW HISTOGRAM with Yes. At the YES (the default setting), the histo-
gram appears on the LCD panel shortly after the exposure, and may be more convenient to
evaluate especially in handheld photography. It works with various digital backs, but the his-
togram may look slightly different depending on the back attached to the camera.
A histogram shows the distribution of the tonal values within an image. Photographers
familiar with the Zone System can think of a histogram as showing the tone values from Zone 0
black to Zone 10 white. On the histogram, the values vary from the black shadow areas shown
at the far left to the pure white highlight areas shown at the far right, with the middle tones in
between. The horizontal spread covers the full potential dynamic range of the digital camera
system. When evaluating the histogram make certain that the graph is completely within the
left and right margins, and that it stops before the margins and is not cut off on either the left
or right side. If part of the graph is cut off on the left, the cut off part is pure black without any
detail and a cut off part on the right is pure white, also without detail. If a very high contrast
subject shows a histogram that goes beyond the margins on both sides, it is better to sacrifi ce
shadow details (the curve going beyond the margin on the left) than blowing out the highlights.
The vertical height of the curve indicates the number of pixels for each tonal value. A
high curve indicates a large number of pixels for that particular tonal value. As a result every