Description Skyoptikst F6.3focal reducer/corrector is suitable for Celestron 5 "6" 8 "9" 11 "and 14" Schmidt Cassegrain SCT telescope, zenith mirror at SCT port, etc., metal structure, two groups of four-piece design, full-band multi-layer coating, which can reduce the focus of your telescope to F6.3 without changing the image quality. This zoom lens/corrector can make the focal ratio of C5, C6, C8, C9.25 become f6.3; The focal ratio of C14 becomes f7. The use of this zoom lens can increase the field of view and reduce the exposure time in astronomical photography. Celestron does not provide the Schmidt Cassegrain telescope of F6.3 because such a design is impossible, and there will be a large central occlusion, which will lead to the reduction of contrast. The defocus lens/corrector of this f6.3 is a 4-piece design with full surface coating. The use of this zoom lens has a good performance in both visual and photography. Name: F6.3 zoom lens Shell material: metal structure Coating: full broadband coating Size: 49X34X55MM Lens design structure: 2 groups of 4 pieces Threaded interface: ScT interface Weight: net weight 0.1KG/gross weight 0.18KG Lens material: glass material Purpose: Reduce the focus of the telescope to F6.3 without changing the image quality There may be errors in manual measurement of the product, please refer to the actual product