1.1   This guidance document has been developed to facilitate the collection of microscopy images with an epifluorescence microscope that allows quantitative fluorescence measurements to be extracted from the images. The document is tailored to cell biologists that often use fluorescent staining techniques to visualize components of a cell-based experimental system. Quantitative comparison of the intensity data available in these images is only possible if the images are quantitative based on sound experimental design and appropriate operation of the digital array detector, such as a charge coupled device (CCD) or a scientific complementary metal oxide semiconductor (sCMOS) or similar camera. Issues involving the array detector and controller software settings including collection of dark count images to estimate the offset, flat-field correction, background correction, benchmarking of the excitation lamp, and the fluorescent collection optics are considered.