An optical system (20) provides a variable dispersion that helps to collect multi-spectral information on an object within the field of view. The system (20) includes at least two sets (24, 26) of optical elements (42x 42y, 44x, 44y) that have minimal deviation of a center wavelength and a non-zero deviation of at least one other wavelength. By rotating the sets of optical elements (24, 26) relative to one another or together, the degree of wavelength dispersion and the direction of the wavelength dispersion can be varied, respectively. By selectively rotating the sets of optical elements, the system also can be operated in a non-dispersed “white light” mode with no net dispersion at the image plane.