Provided are methods, devices, assemblies, and systems for dispensing into the wells of a multi-well device and imaging such wells from multiple Z-planes. Multi-Z imaging of the present methods and systems may allow for the detection of wells of a multi-well device that contain a desired number of cells. Also provided are methods, devices, assemblies, and systems for processing cell-containing wells of a multi-well device identified through the use of multi-Z imaging.