hi all,

Photomicrography in reflected light, using a regular
microscope for biological work in transmitted light, isn't
all that difficult, at least not at low magnifications (up
to about 200x), altough there are some limitations. It can
easily be done with an improvised so-called "mirror acc. to
Lieberkuhn", or more correct a "mirror acc. to Descartes".

In this technique, a central stop (just a piece of black
paper, cut from f.e. the paper sheet in regular 120 roll
film, glued on a slide) is blocking the light that otherwise
would enter the objective trough the specimen. The specimen
has to be smaller than the central stop.

The hole in the table of the microscope has to be rather
large, usualy it's best to remove the condenser.

The parabolic mirror from an old hand torch is placed over
the specimen. If the central hole isn't big enough to permit
the objective to pass, it has to be drilled out.

Most of the time it's neccesary to focus the mirror by
adjusting it's height to illuminate the entire FOV... This
can be done by placing matches under it or by taping it on
the objective at the right height.

Photomacrography is also possible when the microsope has a
wide and short tube.

The technique can also be adapted to provide combined
darkfield/reflected light illumination.

I've placed a few images at the "shared file area":

* Mirror.tif: a drawing of the technique.
* cloth.jpg: woven cloth (polyester Dtex 167), photographed
with this technique, objective LOMO 20x achromat, eyepiece
7xH.
* wood.jpg: wood infected with woodworm, photographed with
this technique, objective LOMO 9x planachromat, no eyepiece.
*poppy.jpg: seeds of poppy flower, objective LOMO 3,5x
planachromat, eyepiece 7xH.

Limitations of the technique:

* Lack of depth of field due to the fact that the entire
aperture of the objective is used
* Achieving even illumination is sometimes difficult
* good ilumination is only possible in one plane, see the
picture "wood.jpg": the "deeper" structures are "in the
dark", the "higher" structures are illuminated properly
(more or less: there's some overexposure on one side of the
picture)

Yvan lindekens.