An illumination system for a microscope, including a light source for generating light to illuminate a sample for microscopic observation, at least one collimating lens for collimating light generated by the light source, and a darkfield condenser for receiving collimated light and directing a hollow cone of light onto the sample under observation. The system optionally includes an adapter for enhancing economy of light transmission from the light source to the specimen, the adapter having a centrally disposed spacer and a plurality of optical fibers surrounding the spacer, to generate a hollow cylinder of light for transmission to the darkfield condenser. The system provides improved resolution and contrast, and is well suited for adaptation to fluorescence microscopy techniques.