Transition in color from yellow to purple in the focal conic texture displayed by the photomicrograph presented above indicates a large gradient in specimen thickness. Textures colored yellow represent the thinnest portions of the specimen, while those transitioning through the colors red, blue and purple are the thickest. The DNA concentration for this specimen is approximately 350 milligrams per millimeter, and the magnification is approximately 300x. The digital image presented above was originally recorded on Fujichrome 64T transparency film using a Nikon Optiphot-Pol microscope with crossed polarized illumination. Exposures were recorded about 2 f-steps under the recommended value given by an in-camera photomultiplier and were push-processed approximately 1 f-steps in the first E-6 developer.