Photographic Set-up for Slime Moulds
The camera is mounted on an old Pentax copy stand. The SLR
camera has a bellows attachment. The lens is a cheapie 24 mm wide-angle lens reversed. You buy a reversal adapter ring and screw it on to the front of
the lens where you normally put a filter. This allows you to revers the lens and you now
have a very cheap, flat-field, super macro lens! You can take magnified images of
the subject depending on how far you extend the bellows. It is a direct
relationship. Divide the bellows extension by the focal length of the lens and you
have the magnification. Since I am using a 24 mm lens then the magnification with a
10 cm bellows would be 4X. If you have a 28 mm wide angle this will do just as well
but you will have a lower maximum magnification.
The specimen is supported on a platform on a tiny jack.
The jack is not absolutely necessary but is very convenient. If you can lower the
arm of the copy stand and raise the specimen independently then things go along much
quicker. The whole set-up must be very rigid and you should certainly use a cable
release for the shutter. Remember, that you magnifiy the shake along with everything
As the years go by, bellows are getting harder to get and are
not cheap. So, if you don't have bellows you can attach the reversed lens to
extension tubes but this is not as versatile an arrangement. You can also attach
extension tubes to your bellows for greater magnification but between reduction in
light intensity and additional shake, it becomes tricky. Remember also, the greater
the magnification the less the depth of field. If you look at my pictures of slime
moulds, you will note that I often have the sporangia in a row and almost in
the same plane. You can also stop down the lens to a very small aperture to increase
the depth, but one of the problems photographing magnified images is lack of enough light
so it is not always possible to use a small lens aperture.
In the woods I prefer natural lighting or at best use a tinfoil
reflector to direct the light on to the subject. In the laboratory at one time I
used incandescent lamps, often photofloods, which seem to put out as much heat as light.
For the more delicate slime moulds and other small things like flowers, insects
etc. that are subject to drying, you have to be very quick or you will cook the specimen
with the lighting before you get the shot. Highly recommended, therefore, is a
fibre-optic lighting system to give you "cold" light on the specimen.
Fibre-optics (Edmund's Scientific) are not cheap but if you leak the right information at
the right time (Birthday, Christmas!) you may get lucky! One light is enough and you
can make a tiny reflector from a white plastic bleach container to kill the shadow or
altenatively you can get a double headed fibre-optic. By the way and very important, there
is a condensor that screws on the front of the fibre-optic to concentrate the light and
this allows you to significantly reduce the exposure time. This doesn't always come
included with the optic and may have to be purchased as an accessory. Remember
also, you must use a film balanced for artifical light e.g Ektachrome 160
But don't worry about all this - in no time at
all we will have digital systems that will make all of the above an anachronism.