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Model: catseye_telecat_xlsPart Number: catseye_telecat_xls
Catseye premium quality Telecat XLS 2" sight tube suitable for f/3.0 - f/5.0 telescopes. Features the same features as the Teletube XLS but with the addition of the Blackcat XL reflective ring enabling it to function both as a sight tube and as a Cheshire as well.
Larger-aperture, low f-ratio Newtonian telescopes with larger diagonal mirrors are becoming the norm, and the need for a precision 2" Sight Tube for properly positioning the Secondary beneath the focuser is a given. The Catseye line of "telescoping" sight tubes feature tuneable "length" capability to obtain the optimum tube-opening/Secondary "gap" resolution for insuring symmetrical intercept of the Primary light cone for maximum FOV illumination and contrast while maintaining axial registration via flush shoulder contact with the focuser draw-tube lip.
For Newtonian's with f-ratio's under f/4.7, the shorter "XLS" model (f/3.0 to f/5.0) is recommended for "seeing" that generous "oversized" Secondary (typical of imaging astrographs).
This is my tool of choice to precisely center my secondary miror under the focuser, it's really precise and easy to use