The 2.5X CCD Compressor Lens is used to widen the field-of-view of 1.25" Digital Imagers on refractors and SCTs. The LL1025 threads into the "nose-piece" of 1.25" Digital Imagers. In its standard configuration (nose-piece to CCD Chip distance of about 1.2"), it yields a 0.4 reduction; i.e. a 1000mm focal-length telescope will become an effective 400mm focal-length system. The lens is of excellent optical quality, with a minimum spot-size of about 20-microns, matching the pixel size/resolution of common CCDs.