Basic Photography Tips
Digital close-ups – by Basic Photography Tips
In the past, true close-up photography required specialist equipment and fiddly
accessories. However, this situation has entirely changed thanks to the introduction
of digital cameras. These cameras work at close-up subject distances as if they
were designed for the job.
Short focal length
Digital’s ability to handle close-ups is due to two related factors. First, because
the sensor chips are small, lenses for digital cameras need have only short focal
lengths.
Second, short focal length lenses require little focusing
movement in order to bring near subject into focus. Another factor, applicable to
digital cameras with zoom lenses, is that it is relatively easy to design lenses
capable of close focusing by moving the internal groups of lens elements.
In addition to lens design, there is another feature common to digital cameras that
also help: the LCD screen. This provides you with a reliable way of framing close-ups
with a high degree of accuracy, all without the complex viewing system that allows
traditional SLR’s to perform so well.
There will be occasions when you need to keep a good distance between yourself and
the subject a nervous dragonfly, perhaps, or a bee-hive. In such cases, first set
the longest focal length on your zoom lens before focusing close up. In these situations,
an SLR-type digital camera (one that accepts interchangeable lenses) is ideal, due
to the inherent magnification given by the small sensor chip working in conjunction
with lenses designed for normal film formats.
Digital depth of field
On the one hand, the closer you approach your subject the more rapidly depth of
field diminishes, at any given lens aperture. On the other, depth of field increases
rapidly as focal length decreases. So the question is whether the increase in depth
of field with the short focal lengths typical of digital cameras helps make close-up
photography easier than with film-based equipment? The calculations are not straightforward,
partly because in order for the shorter focal length lens to produce a given magnification,
it must approach closer to the subject than a longer lens, which works against the
increase in depth of field.
Setting the aperture
Another confusing factor is that digital cameras, with their regular array of relatively
large pixels, cannot be treated in the same way as film-based cameras, whose images
are based on a random collection of tiny grains of light-sensitive silver. With
many digital cameras, you do not have the option of setting apertures at all, and,
even when you do, the minimum aperture may be relatively large — say, f/8. Nonetheless,
taking all these factors into account, depth of field often appears greater with
digital photographic equipment than with conventional cameras.
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