Bright-field microscopy typically has low contrast with most biological samples as few absorb light to a great extent. Staining is often required to increase contrast, which prevents use on live cells in many situations. Bright field illumination is useful for samples which have an intrinsic colour, for example chloroplasts in plant cells.
Comparison of transillumination techniques used to generate contrast in a sample of tissue paper. 1.559 μm/pixel.