Efficient functioning of the human body involves a multi-level synthesis emerging from collective brain activity to the immune system. Understanding the complex interactions of the molecular processes underlying these mechanisms is one of the main objectives of biomedical research in order to achieve optimal prevention, diagnosis, and treatment. Scientifically, it is important that the methods do not influence the biological system during observation. The most suitable tool that can cover all of this is optical far-field fluorescence microscopy. Yet, biomedical applications often demand coverage of a large range of spatial (nanometers to larger than micrometers) and temporal (microseconds to minutes/hours) scales, and/or long acquisition times (low phototoxicity), which can so far not all be covered by a single microscope and puts some challenges on microscope infrastructure. Taking immune cell responses and plasma membrane organization as examples, we outline these challenges but also give new insights into possible solutions.