The bin shed roof (II) or: the blue backside
Some facts are definitely easy to understand, but definitely easy to overlook and forget as well.
As most of you will know, we had been almost exclusively using the Russian MBS-10 stereo microscope for
the screening of our tardigrade petri dishes:
April 2012,
May 2012 und
June 2012).
One of the biggest advantages of the MBS-10 is its huge working distance of ca. 10 cm.
On the other hand we should be aware of the fact that high microscopic resolution
will always be based on a rather low working distance. Admittedly, there are some exceptions, e.g. so-called
long distance objectives but as a rule we must approach our objects in order
to gain maximum detail information: the respective objects are sending light rays in all directions
and in order to catch all those rays, including the most oblique ones we must be as close
as possible. This is the concept of numerical aperture (the angle of view which can be reached
by a given objective).
Coming back to our MBS-10 we must accept that this instrument is primarily designed for
comfortable preparation work and a large field of view. But, as there is always
a trade-off between working distance and resolution we have to accept that maximum
resolution cannot be the strong point of the MBS-10 microscope,
In order to illustrate this we will have a look at one of those old-fashioned
stereo microscopes with interchangeable conical objectives of different aperature (different magnification):
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