Stereo or Compound Microscope - Which To Buy

Discussion forum for organisms requiring a microscope for identification and techniques to achieve this aim.

Stereo or Compound Microscope - Which To Buy

Postby SteveMcBill on Mon Feb 01, 2016 7:54 pm

Stereo or Compound Microscope - Which To Buy ?

There are two types of light microscopes, the compound microscopes and the stereo microscopes. Stereo microscopes are also sometimes referred to as dissecting microscopes because they are are also used during dissection of plants and animals. Both of these types find their use in amateur microscopy and in species identification. Many hobby microscopists own both types.

Unfortunately, there are some naming issues, which might cause confusion. Compound microscopes are named this way, because they have (in contrast to simple microscopes), two systems of lenses. One is the objective, and one the ocular. Simple microscopes are made only of one lens, essentially they are a magnifying glass.

Stereo microscopes, however, also have two lens systems, objective and ocular. In that sense, stereo microscopes are, strictly speaking, also “compound” devices. In order to prevent confusion here, I have seen some people refer to the non-stereo microscopes either as “normal microscopes” or “biological microscopes”. I have to admit that neither of these two terms are appropriate. Stereo microscopes are also normal, and they are also used in biological research and species/specimen manipulation and identification.

You can observe most of the objects with either of these two types. Sometimes one microscope type is more suitable; in other cases the other type is more suitable. It depends much on the size of the object that you want to look at, and also on whether the object allows light to go through (is opaque or transparent/translucent).

If you want to look at large objects, such as whole insects, flowers of a plant or rocks and minerals, then a stereo microscope is better suited. For looking at small objects, like microscopic pond life or thin sections of plant and animal tissue, it is better to use compound microscopes.

Compound microscopes have the advantage that they allow you to magnify an object to a much greater extent (up to 1000x) compared to a stereo microscope (max. about 100x). Compound microscopes also have disadvantages. Not every object is suitable for observation. Objects that are too thick or too dark will simply not produce an ideal image, or you are simply not able to see anything at all. It is not possible, for example, to take a large insect and observe it under the compound microscope as a whole. You will only see a dark shadow without many details. If you are interested in observing large or opaque objects, then a stereo microscope would be better suited. In order to view these objects under the compound microscope, you must first process them by either cutting them into thin sections (called microtoming) or by other methods.

Stereo microscopes have light coming from above and allow you to observe the surface texture of objects. Stereo microscopes therefore allow you to look at pretty much anything that will fit on the stage and there is no need to prepare the object so that it fits on a microscope slide. Stereo microscopes even allow you to see the object stereoscopically (3 dimensionally). A lower magnification of about 40x-100x may still be enough.

Each microscope type has its own advantages and disadvantages and the choice depends much on what you want to observe. People who are interested in observing whole insects or plants may most likely chose a stereo microscope, while those who are interested in viewing the much smaller individual cells (blood, fungal spores, etc.) or microscopic organisms (desmids, diatoms, rotifers, etc.) should go for a compound microscope.

There is one important point that is often a source of confusion. Some compound microscopes have a binocular head with two eyepieces. These microscopes should not be confused with stereo microscopes, which also have two eyepieces. Compound microscopes are not capable of delivering a stereoscopic (3D) image, even if they have a binocular head.

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