Brightfield illumination is probably the most widely used observation mode in optical microscopy. The technique is best suited for obervation of fixed, transparent and therefore stained specimens or other kinds of samples that naturally absorb significant amounts of visible light. Images produced with brightfield illumination appear dark and/or highly coloured against a bright, often light grey or white, background.

Reflected Brightfield is used to observe the light reflected directly from opaque specimen mainly in materials science and geology. The light from the illumination lamp is vertically guided through the objective onto the specimen. The light reflected from the specimen is observed through the objective.