In this issue we will discuss a very, very special topic: what is the best
way to take a photograph of an egg? As we are within the
Water Bear web base area, we will not discuss
this for everyday hen eggs, of course, but for water bear eggs only.
As a rule sphaeroidic or egg-shaped objects are difficult to master
under a light microsope - in particular when they are not fully transparent.
The limited focus depth will not be sufficient to render a crisp image
of the overall object. Instead, we will get optical "slices" only.
This has been an important argument for teachers not to forget drawing
techniques as the only means to collect all the information of the various
focus slices into one combined representation covering all details of an object.
So one might end up in thinking that light microscopic photography of those
"thick" objects would always end up in an imaging catastrophy.
Of course this would be a pity. Some of the water bear eggs are real
marvels of 3D construction symmetry similar to those fascinating,
diatom shells and
Now the microscopic amateur living somewhere in our really incredible
microscopic & networking world might take out his "Gerlach" book (in Germany)
or another comprehensive textbook covering microscopy and might have
a look at the curves representing the relations between objective properties,
overall magnification and focus depth.
For a 40x objective with a numerical
aperture of 0.65 the theoretical value of focus depth is about 2 microns only.
This sounds not very good when keeping in mind that the typical water bear egg
is about 0.1 mm in diameter which mean als that it is 0.1 mm (100 microns)
in depth as well.
We might photograph the different focus slices and study them in series,
one by one: