About this product
Part Number: catseye_teletube_xl
Catseye premium quality Teletube XL 2" sight tube suitable for f/3.5 - f/6.0 telescopes.
- Large 1.759" Aperture.
- Telescoping length adjustable from:
- XL: f/3.5 to f/6.0
- XLS: f/3.0 to f/5.0
- Slide Position Locking Set Screws w/hex wrench.
- Calibrated f/no. Ruler accessory marked in f/.1 increments.
- Precision machined from T6061-T6 Aluminum & Black Delrin.
- 90-degree Intersecting .029" diameter Stainless Steel cross-hairs.
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).
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