Compound, Stereo or Digital?
A compound microscope is the kind of microscope that people imagine when they hear the word "microscope." As you might suspect, the name of the compound microscope originates in its multi-lens design. The "objective" is the magnifying part of the microscope separate from the eyepiece. The total magnification is calculated by multiplying the power of the objective by that of the eyepiece. It is common for compound microscopes to have several objectives mounted on a rotating turret to allow quick power adjustments.
Because the design is relatively simple and these microscopes are widely available, this type of microscope is often used in life sciences and medicine. Compound microscopes are often referred to as "biological" or "research" microscopes. Typical magnifications range from 40x to 2000x, with the final image being two-dimensional, reversed, and upside-down.
The stereo microscope earns its name from offering a three-dimensional view of objects, but at much lower resolution than other microscopes. It achieves its three-dimensional view by using two complete magnification systems composed of objective, prism and eyepiece. The advantage to using a stereo microscope is that objects can be observed with depth and manipulated at the same time. The paired optics provide a right-side-up and a normal (as opposed to reverse) image. Because they provide depth and detail, but only low magnification (around 10x to 80x), stereo microscopes are great for stamp and coin collectors, entomologists, and others who are looking at larger items.
You may be confused when trying to distinguish stereo and binocular microscopes. The latter have two eyepieces mounted on a single objective and prism, providing the comfort of using both eyes, but still delivering a two-dimensional image.
"Digital microscope" has taken on a whole new meaning. Today, inexpensive digital microscopes are available for home use which sometimes creates confusion with the digital microscopes costing thousands of dollars that are used in science laboratories. Whether your digital microscope is in your home or in your lab, there are loads of accessories for all budgets. There are even accessories that can be attached to an existing microscope to capture a digital image of a slide and saved on a computer. There are also microscopes with built-in digital functionality and a viewing screen. Surprisingly, such technology might cost as little as 200 dollars or as much as thousands. Naturally, the sky is the limit on cost for this category.