A telescope for viewing high frequency radiation (soft X-ray, extreme ultraviolet) is described. This telescope has a long focal length with a selection of magnifications despite a short housing. Light enters the telescope and is reflected by the telescope's primary optical system to one of several secondary mirrors at different locations on a movable frame. The secondary mirrors have varying degrees of magnification and select narrow spectral slices of the incident radiation. Thus, both the magnification and effective focal length field of view and wavelength can be altered by repositioning the moving frame. Configurations for spaceborne applications are discussed
