Geoscience Reference
In-Depth Information
12 Photography
Angela L. Coe
12
Photographs are a key part of most geological fi eldwork. They
can serve as an aide memoire , be used for image analysis
(Sections 5.4 and 5.5), to document changes in an exposure
over time and are also essential to illustrate key geological
features in a report, talk or publication. As outlined in Section
4.3 it is very important in the fi eld not only to take a
photograph but also to make fi eld notes and sketches, because
a photograph is not a replacement for a fi eld sketch. A fi eld
sketch records how you have divided up the succession,
provides a key to further notes and shows some geological
interpretation. The photographs taken should be recorded in
your fi eld notebook and electronic information on the
geological features and location added either through the
camera or image processing software (Figure 12.1).
(a)
The detailed advantages and disadvantages of the wide range of
cameras available on the market are outside of the scope of this
book, so here we provide some general comments. Digital
single-lens refl ex (SLR) cameras provide the most amount of
fl exibility for a range of lighting conditions and types of
photograph; they also generally have better lenses. However,
many compact cameras give excellent results and have the
added advantage that they are small and light. As with
Personal Digital Assistants (PDAs), etc. (Section 2.9), check if
the screen is visible under strong lighting conditions. This is
essential when the camera does not have a view fi nder. If the
camera does have a view fi nder but is not an SLR, the view
fi nder does not usually give an exact representation of the
frame of the photograph so you may need to work out exactly
what that is if you wish to frame your subject exactly. Even
with digital SLRs the view is not exactly the same. Cameras
with good reviews for outdoor and scenic use will probably
give the best geological fi eld photographs. A good macro lens
setting is advantageous if you are going to take a lot of close up
photographs. In addition cameras that are sensitive to a wide
range of lighting conditions allow maximum fl exibility.
(b)
Figure 12.1 Two photographs
taken under slightly different f-stops
to illustrate the effect of varying the
camera settings. Images are 40 cm
high. (a) f 6.3 and (b) f 4.5. The
associated metadata that it is useful
to include in an electronic fi le are:
camera type, shutter speed, f-stop,
ISO setting, white balance (see
Figure 12.2), focal length, date,
time, place, subject, keywords.
Some of this is recorded
automatically and other parts such
as the subject matter need to be
added by the user. (a and b:
Angela L. Coe, The Open
University, UK.)
There is almost no limit to the number of photographs you can
take with a digital camera, provided that is you have enough
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