Diffractive wavefront control with programmable optically efficient modulo λ gratings was previously demonstrated as a means of extending the capabilities of a telescope system by compensating large aberrations associated with variations in object range and field angle within the telescope’s field of regard. Inherent in diffraction phenomenon, however, are wavelength dependences that impose limitations on operating spectral bandwidths. This paper builds on past work integrating a programmable diffractive element of large pixel count with a telescope system. We present a theoretical evaluation of the wavelength-dependent performance characteristics of a modulo λ diffractive aberration compensator and experimental demonstrations of wavelength-tunable and extended spectral bandwidth operation. Near-diffraction-limited-resolution imaging is demonstrated within the spectral operating limits imposed by diffraction theory. © 2005 Society of Photo-Optical Instrumentation Engineers.