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Peter Bresler

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Custom Built 100mm F-13 Refractor with Carton Objective

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Custom Built 100mm F/13 Refractor with Carton Objective

  • Includes 9X50 RACI illuminated finder, laser finder, dual speed 2” Crayford focuser, 2” diagonal, scope rings, mounting plate, and solar filter.
  • Very good condition. No scratches or dents.
  • Ray traced and fully baffled
  • Long-travel focuser allows prime focus photography
  • Objective is Carton NOS (New Old Stock) 100mm F/13 achromatic objective with Magnesium Flouride coating. This is one of the best objectives ever made.  Quoting Ed Ting from his Carton 100mm F/13 Telescope Review: “The Carton notched .9 arc-second Eta Corona, which is well below the 1.1 arc second theoretical limit for a 4" telescope. Porrima, Izar, and Xi Ursa Major all proved easy fodder for it, and I cannot wait to look at Saturn when it comes around again. Even at 500X, the scope's airy discs are tight, round little balls with a dim first diffraction ring. This is the way stars are supposed to look, and we don't see it often enough.” 
  • This refractor was built with all high-end components:
    • Carton 100mm F/13 Fraunhofer Doublet Objective with MgF2 coating
    • 1/16” thick wall aluminum tube
    • Epoxy paint
    • Custom machined, rotating, long travel 2” dual speed Crayford focuser by Dan Crawford (Crawmach Machining), fully anodized
    • Custom machined fully adjustable push-pull objective mount by Crawmach, fully anodized
    • Carton lens shade
    • Hinged, quick-release tube rings tapped 1/4-20 for camera mounting
    • Losmandy DUP14 Universal dovetail mounting plate
    • Astrotech 99% reflectivity 2” dielectric mirror diagonal
    • Stellarvue F50-M2 RACI (right angle correct image) illuminated 9 x 50 finderscope and mounts
    • Hotech laser finder on Orion mount
    • Solar filter made with Baader film provides excellent sunspot viewing
    • All stainless steel fasteners
    • Dust cover
  • This scope provides sharp, high contrast observing and at F/13 it is well within the Sidgwick criteria and has no chromatic aberration issues.
  • Local pickup only. I really don’t want to take a chance on this scope getting damaged during shipping, and then going through the hassle of an insurance claim.

Price for scope and all items detailed above is $875.   I have $1200 invested in this scope and many hours of labor.   Recently a home-made refractor with a 100mm Carton objective sold on the Carton Club web group for $1100, and it had no finderscope or diagonal.

I also have an excellent equatorial mount, a Losmandy GM-8 with digital tracking.  The mount is in very good condition and has the optional anodized aluminum motor covers, an optional Losmandy G-11 saddle plate (G11SPTAK), an additional 11 Lb counterweight; custom eyepiece tray, and Gel Cell 12V battery.  I have $1150 invested in the mount.  I will sell the telescope and the mount together for $1700.