Ernst H.K. Stelzer is the Professor for Physical Biology and Advanced Light Microscopy at the Goethe-Universität (Frankfurt am Main, Germany) since March 2011. The newly founded professorship is part of the Cluster of Excellence for Macromolecular Complexes (CEF-MC, EXC 115) funded by the German Research Council (DFG). Stelzer concentrates his efforts on applications and further developments of advanced light microscopies in the modern life sciences, working on various aspects and applications of three-dimensional cell biology, lateral root development in Arabidopsis thaliana and the embryogenesis of, amongst other insects, Tribolium castaneum. His instruments allow scientists to observe and manipulate biological specimens efficiently, with high precision and high spatio-temporal resolution. From 1987-2011, he was a Scientific Group Leader in the European Molecular Biology Laboratory (EMBL, Heidelberg, Germany), most lately in the Cell Biology and Biophysics Unit. Stelzer worked in physics, optics, biophysics, cell biology, molecular biology, plant biology and developmental biology for more than 35 years. He contributed to conventional and confocal fluorescence microscopy, 4Pi- and theta-microscopy, optical tweezers and levitation, laser ablation and invented light sheet-based fluorescence microscopy (LSFM, SPIM, DSLM). His publications continue to influence optics, biophysics, cell biology, developmental biology and plant biology. In more general terms, he is particularly interested in developing three-dimensional microscopies that enable observations of three-dimensional specimens under near-natural conditions as a function of time. Many of his former Diploma and Ph.D. students as well as Postdocs continue to pursue successful academic careers of their own. By now, he published more than 270 papers and was granted several patents that secure the intellectual property of at least three commercially available optical instruments. He received several prices and honours. In 2015 light sheet-based fluorescence microscopy was honoured as “Method of the Year 2014” by Nature Methods.