8" f/6 Primary Mirror + 40mm Secondary & Spider Assembly — ATM Parts, Sold Separately or Together — Free CONUS Shipping
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Two Newtonian optics from different sources, listed together because the sizes work for the same build. Buy either one alone or take both.
1) 8" f/6 Primary Mirror — $135
Marked "F6" on the back with a QSP Optical Technology, Inc. (Santa Ana, CA) label. Approximately 8" diameter, approximately 1.25" thick. Professionally coated and center-marked.
I have no documentation on figure, wavefront, or the original telescope, so it sells as an unidentified 8" f/6 primary. The coating is reflective and gives a bright image — reflection shots of distant objects are in the photos. There is scattered pinholing visible under a bright backlight and a small area of edge coating loss. No chips, cracks, or significant scratches. Surface is clean. Sold as-is.
Good candidate for an ATM project, a restoration, or a recoat.
2) Secondary Mirror, Holder & Spider — $55
Maker unknown. Elliptical secondary measures 40.42mm minor axis by 54.74mm major (about 1.59" x 2.16") by caliper — caliper photos included. Mounted in a black round holder with a center-bolt tilt/collimation adjustment. Three-vane spider, 8-1/4" tip to tip, sized for roughly an 8"–8.5" ID tube. Vane ends are threaded for tube bolts.
Coating is bright and even with no pinholes or edge lift that I can see. Light dust only. Paint on the holder and vanes is sound with minor handling marks.
3) Both — $170
They didn't come from the same scope, but the numbers happen to line up well. A 40mm minor axis on a 203mm f/6 works out to a 19.9% central obstruction by diameter — under 4% by area — and still gives roughly a 14mm fully illuminated field at a typical focuser height. That is a visual-optimized pairing, and the 8-1/4" spider drops straight into the same tube. Between the two you have most of the optics for an 8" f/6 Newtonian.
Not included: primary cell, tube, focuser, or hardware beyond what's shown.
All prices include shipping, insurance, and PayPal fees within CONUS. International at buyer's expense. PayPal preferred; other methods considered.
Questions or more photos, just ask. Thanks for looking.
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