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Description Description Originally developed to tame the focal length of our 10" f/14.6 Mak-Cass, this telecompressor is optimized for scopes ranging from f/9 to f/18 focal ratio. The 2-element cemented design transmits close to 99% of the incoming light over the range of 420 to 700 nm. The focal length of the telecompressor optics is 305mm (12"). For refractors, the field is compressed by 0.67x. If you have a moving mirror system, the native focal ratio will increase. This optic is not recommended for telescopes with f/ratios below about f/8-9. For faster instruments, we recommend the Photographic-Visual Telecompressor (27TVPH). The CCDT67 design allows full corner-to-corner illumination up to an 8300 or APS-C size chip with most catadioptric telescopes. This design does not add coma to the wavefront, and thus, can be used with all flat-field and coma-free telescopes such as Maksutov-Cassegrains, Schmidt-Cassegrains, Ritchey-Chretiens and long-focal-length refractors. The inherent resolution of the telescope is not compromised when using this compressor. Please review the exploded diagram to see how this item will fit into your imaging system. If you want a higher compression ratio, you can add one or more of the 2" Nosepiece Extension w/ 48 mm Threads (EXT48-12.7, previous part # A3703) between the CCDT67 and the nosepiece of your camera. This has the advantage of inserting the CCDT67 forward in the light cone so that in-travel requirements are reduced. Please note that as you increase compression, you decrease the size of the image circle at the focus point. At 0.67x, the CCDT67 will have a 29 mm image circle. It will not cover a full-frame size chip. To calculate the compression factor and coverage for your particular setup, please refer to our Telecompressor Spacing, Compression Calculation and Coverage document or to the CCDT67 & 27TVPH Telecompression Graph. Clear aperture is 44.5mm (1.75"), designed to screw onto our 2" Secure-Grip Nosepiece (AP16T) or a

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