A multi-band aperture filter for optically coupling to a focal plane array (FPA) of a camera includes a substrate, and a first spectral coating on a first surface of the substrate that passes both a first longer and a second shorter wavelength band. A second spectral coating that passes the longer wavelength band and blocks the shorter wavelength band is on an outer annulus region, but not on an inner region on the first surface or a second surface of the substrate. The second spectral coating provides a larger aperture area for the longer wavelength band as compared to an aperture area for the shorter wavelength band to passively realize different F-numbers for the bands to provide substantially matched beam spot sizes on the detector array for the longer wavelength band and the shorter wavelength band, such as a long-wave infrared (LWIR) band and a mid-wave IR (MWIR) band.