A rule-of-thumb guide for choosing, among wide-field and/or 3D-deconvolution microscopy (WF/3D-D), spinning-disk confocal microscopy (SDCM), and spot-scanning confocal microscopy (LSCM), the most appropriate mode of microscopy for a thick specimen. The magnitude of the ratio of out-of-focus background to the in-focus signal from a small object, which is a specimen-dependent parameter, determines the choice. For details, see Murray et al. (2007).