Two nested all-reflective afocal telescopes providing four fields of view

An all-reflective multiple field of view optical system comprising:

• an entrance pupil region;
• a first reflecting assembly having a primary mirror with a central axis, a secondary mirror facing said primary mirror such that light from a viewed object is reflected by said secondary mirror, a tertiary mirror positioned to receive light from said secondary mirror and a quartenary mirror positioned to receive light from said tertiary mirror, such that said quartenary mirror reflects an image of the object being viewed to a plane for viewing;
• a second reflecting assembly including a primary mirror having a central axis, a secondary mirror facing said primary mirror such that light from a viewed object is reflected by said secondary mirror, a tertiary mirror positioned to receive light from said secondary mirror and a quartenary mirror positioned to receive light from said tertiary mirror such that said quartenary mirror reflects an image of the object being viewed to said plane for viewing;
• and
• said first and second reflecting assemblies being movably positioned with respect to one another such that in a first position one of said assemblies reflects light from said entrance pupil region to said plane for viewing and in a second position the other of said assemblies reflects light to said plane for viewing, wherein the fields of view and afocal magnification of said first and second reflecting assemblies are different.