Fly Times Issue 48, April 2012 - North American Dipterists Society

6
minimum working distance for comfortable focusing on a specimen. This distance is an important
figure to keep in mind when selecting lenses for photographic work when using a dome light.
Stereoscopic microscopes: dome lights work well beneath stereo scopes, almost always providing
superior light for photography than other kind of lighting (fiber optic lights, conventional ring lights,
incandescent and halogen lights, etc.). A variety of camera types can be fitted to trinocular ports or to
eyepieces, and these will produce good images. The compact size and light weight of these dome lights
make them excellent choices for using when traveling to museums and collections – where they will
provide you with very dependable lighting for photographing specimens.
Photo stands: this is where dome
lights really excel – on photo stands
that are setup for image stacking – in
order to produce extended depth of
field images. With these setups, a
microscope is unnecessary and the
images are produced solely with
digital cameras and lenses. With
photo stacking, numerous images are
needed (sometimes hundreds), and a
dome light is perfect for providing
continuous, stable lighting of the
same exposure setting. Flash
photography, for example, will
occasionally produce improperly
exposed images, and these need to be
corrected immediately – in the proper
sequence – or the final stacked image
will have some off-color layers. Flash
photography is also relatively
expensive and can be inconvenient
(either needing a constant exchange
of batteries or pricey studio-lighting
flash units).
Example of photo stand: most of my
Fig. 5: Photo stand with dome light
‘dome lighting’ these days is done
with a photo stand for purposes of image stacking (see. Fig. 5). This particular setup uses a “Canon
EOS 40D” camera, mounted to a sturdy focusing rack that is attached to the adjustable arm of an
Olympus photo stand for microscopes. The dome light rests on a movable table attached to a “Newport
462 linear XYZ stage.” (Also present are flexible arms holding the “Twin Lites” of a Canon “24EX
Macro Flash” – which are seldom used of late.) The photo stand holds the camera very steady at varying
positions and heights, while the linear stage is capable of adjustments as small as .002mm. The Canon
EOS system is excellent for photo stacking because of an ability to take vibration-free images, and
because of “Live View” – where the camera can be tethered to a computer by a USB cable, and all
image shooting is then done remotely from the computer monitor, using a mouse. One key benefit of
my photo stand setup is that vibration, which is a major cause of problems in high resolution
photography, is reduced to an absolute minimum. (Most of the hardware shown in Fig. 5 was purchased