An imaging system includes a wavelength dependent aperture stop, which transmits light with different ranges of wavelengths through apertures of different diameters. Thus, different colored light will have different F-stops, which can be selected based on the power transfer and image quality requirements for the different colored light. For example, a smaller F-stop may be used with a weaker light source to produce a higher throughput for a specific range of wavelengths. Accordingly, the optical system's design and optimization is wavelength and F-stop dependent.