A light microscope normally consists of four objective lenses - a x4, x10, x40, and a x100 lens. The x100 lens is usually an oil immersion lens. The eyepiece lens also adds x10 to the microscope.
Those numbers are the magnification that the light microscope can show you. Magnification is a measure of how big an image is seen to be compared to how big it actually is. The highest magnification that the light microscope will provide you with is x1500.
Resolution is the ability to distinguish between two seperate points. The higher the resolution, the better the detail. The highest resolution a light microscope will give is around 200nm - because of the wavelength of light. Any closer and the objects will appear as one point.
To prepare a specimen for viewing using the light microscope, it is often `stained` or `sectioned`. Staining the specimen is using a chemical to add colour (by binding to other chemicals on the specimen or otherwise). For example, Acetic Orcein stains DNA dark red. Sectioning involves embedding the specimen in wax, so it can then be cut into strips for viewing. This is to help with soft, delicate pieces of tissue.
Staining:
Sectioning:
A sectioned kidney (not the best example to use with a microscope).
A formula to use with magnification is:
Actual size of specimen = Image size (measured via microscope measuring utensil or using an image provided) / Magnification of image
Or I=AM
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