We report on a novel zoom lens with no moving parts in the form of a switchable Galilean telescope. This zoom telescope consists of two flat liquid-crystal diffractive lenses with apertures of $10\mathrm{mm}$ that can each take on the focal lengths of $-50$ and $+100\mathrm{cm}$ , with a spacing of $50\mathrm{cm}$ and, hence, a zoom ratio of $4\times$ . The lenses are driven using a low-voltage ac source with $1.6\mathrm{V}$ and exhibit millisecond switching times. The spectral characteristic of this diffractive zoom system is evaluated for light sources of various bandwidths. Potential applications for this technology include a zoom lens with no moving parts for camera phones and medical imaging devices.