PanoMachine Panorama Calculator Operators Manual
Copyright by Josef Ehrler
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3 Bracketing Calculator
In panorama photography each picture is associated to a fixed exposure value. The
reason for this is to assure a constant depth of field for all pictures. Normally for each
camera position one picture will be taken. The photographer has to decide correct
shutter and exposure values to consider highlights and shadows. Dynamic range,
found in most situations while taking a panorama, is too small to cover the highlights
and shadows. To overcome this problem special programs are available on the market
to increase the dynamic range of each picture or even a whole panorama. This is
done by calculating e.g. three shots of the same picture with different exposure values
to composing a single picture or a whole panorama. This technique is also known as
High Dynamic Range (HDR) enlarging. The “Bracketing Calculator” should help the
photographer to estimate the correct shutter speeds in coherence to a fixed exposure
value.
How to use the Bracketing Calculator?
To ensure the highlights are exposed correctly and not overexposed, it is important to
measure the belonging aperture and shutter speed, if possible, with the spot meter se-
lected on the camera. The lower end of the dynamic range, the dark areas, should be
measured too.
An Example:
Let say the measured shutter speed and aperture for the highlights, the
upper limit of the panorama dynamic range, are 1/500” respectively f/8. As mentioned
above the aperture stays unchanged during the whole panorama shooting. This is
necessary to secure constant depth of field for each image. The second measurement
for the shutter speed, the dark areas, we get 1/15” by a still unchanged aperture f/8.
To avoid fuzziness from moving elements, it is important to take care, the shutter
speed at the lower end of the dynamic range (dark areas) is not too long. If so, just
use a higher shutter speed when measuring the bright areas in the panorama. Simul-
taneously the aperture will be decreased and ends in a smaller depth of field.
First calculation
First, we set the shutter speed and aperture, measured for the bright areas, into the
Bracketing Calculator by using up/down arrows. Next we set a trial number of images,
used for each camera position, let say 5. Finally set the EV-step size to 2 f-stops. With
these presets the first calculation should be done.
The calculated shutter speed for the lower end of the dynamic range shows the value
0.5” and is far away from the measured 1/15”. With this shutter speed, the dark areas
would be very overexposed – too bright.
To be sure the full dynamic range will be captured, it is a good practice to expand the
dynamic range by 1 to 2 EV on each side of the dynamic range. That means, to re-
duce the shutter speed by 1 to 2 EV for the dark areas and increase the shutter speed
by 1 to 2 EV for the bright areas.
