There are several uses for a dissecting microscope, although it is often found in middle and high school laboratories because of its function in medical and biological applications.  However, the low magnification common in dissecting microscopes make them the best choice for crafts such as watch making and for industrial uses such as building and inspecting circuit boards.  The dissecting microscope works in much the same way as other microscopes, but with a few differences.

How a dissecting microscope is built
The dissecting microscope is built similarly to other types of microscopy, in that it also utilizes a tube that contains a lens at the upper end.  Another lens, called the objective lens, is found on the other end of the dissecting microscope.  The objective lens is the part of the optical system that is responsible for producing a refined image of the specimen.

The dissecting microscope also features a condenser, found approximately in the middle of the stage.  These lenses help improve the magnification power of the microscope by controlling the light.  On a dissecting microscope, the condenser ‘collects’ the light from the illuminator (the microscope lamp or light from a substage mirror) and focuses it on the specimen.  This produces a high resolution image of the object, allowing the viewer to see better contrast.

Another helpful component that helps a dissecting microscope work as it should is the diaphragm, found under the specimen stage.  It also regulates light that passes through or bounces from the specimen, so each time a sample is viewed, there is hardly any need to adjust the illumination.  Light is only dimmed or increased if conditions are less than ideal.  Otherwise, it is hardly touched.

Adjusting the dissecting microscope
One thing to remember about dissecting microscopes is that these are often equipped with lower magnification power.  Its lowest magnification lens, for example, starts at 7x or 7.5x while other types of microscopes start at 10x.  However, this low magnification is enough to help the observer view the image of the sample for detail inspection during dissection.

Illumination in a dissecting microscope
Most dissecting microscopes light up the specimen from the top.  This is because almost all specimens that are dissected are opaque or solid objects.  With this type of density, reflected light from a specimen coming from a lighting source from the top is usually best.  With newer dissecting microscope models, observers are able to regulate the intensity of the light using a built-in control.

Most dissecting microscopes come with a built-in light source and there are also some that are supplemented with a substage mirror.  This mirror can be focused substage or under the specimen to add light or provide light when the microscope is used in the field with no electric power source.  This type of illumination is also used when the object being viewed is translucent or transparent.  These types of objects allow more light to pass through and are best viewed using substage lighting.  If the lighting does not suffice, an external illuminator may also be used to light up the object.

Focusing
Most dissecting microscopes come with an auxiliary lens, also called a supplementary lens.  This lens is located below the specimen stage and may be used to add to the standard magnification power of the dissecting microscope.  Dissecting microscopes come with a focusing feature, usually composed of a coarse focus and a fine focus.  When viewing a specimen for inspection, illustration or cutting, it is often not necessary to see the minute details so the focus mechanism is merely to refine the view of the image.  Quality dissecting microscopes offer high resolution, which produces a better contrast of the image.

When a specimen is first viewed, contrast is adjusted using the coarse focus knob.  For general viewing, this usually suffices, especially if a lower magnification power is used.  If a higher magnification power is required, the fine focus is often used to refine the image produced with the coarse focus.  With fine focus, for example, an observer can view fungi and other types of plant diseases growing on plant parts, something that may not always be available using lower magnification and a coarse focus.

Mounting the specimen on dissecting microscopes
Dissecting microscopes are used primarily for viewing and manipulating a whole specimen or some parts of it.  Insects and plant parts can be easily mounted on the stage to be examined.  Most dissecting microscopes come with two detachable rests, one for either side of the specimen stage.  These rests often come in handy for steadying hands and arms during delicate dissecting work.  For viewing purposes only, these rests may be removed and stored.