Instead of sawing off a piece of the tube, can't you just use
these binoviewers that claim to not affect the optical path and keep the focuser distance the same? It's only for 1.25" but at least you can keep your frac resellable if what they claim is true.
TS also has a
nice collection of astro binos if you want to avoid using binoviewers. Should be
F/4 or so with 10 mm eyepieces.
... Henk.
Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80,
Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall,
Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS,
DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles,
Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50,
Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK,
Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17",
Website:Henk's astro images