Advantageous instruments, assemblies and methods are provided for undertaking imaging techniques (e.g., microscopic imaging techniques). The present disclosure provides improved imaging techniques, equipment and systems. More particularly, the present disclosure provides advantageous microscopy/imaging assemblies with rapid sample auto-focusing (e.g., microscopy/imaging assemblies having instant focusing for rapid sample imaging with auto-focusing). The present disclosure provides for high-throughput whole slide imaging with instant focal plane detection. A whole slide imaging platform/assembly that uses instant focusing systems/methods for high-speed sample autofocusing is provided. Such exemplary platforms/assemblies can be used for digital pathology or the like, and can provide improved, faster and cheaper diagnosis/prognosis of ailments/diseases. At least two exemplary rapid-focus systems for whole slide imaging are provided, a first system including two pinhole-modulated cameras mounted on the eyepiece ports of a microscope platform/assembly, and a second system including one pinhole-modulated camera mounted on the epi-illumination arm for auto-focusing.