We offer knobs for the Astro-Tech, GSO, iOptron Photron, MallinCam VRC, Orion (US), and TPO OS 6”, 8”, 10”, 12”, and 16" Ritchey-Crétien secondary. Select knobs for your telescope from the list below. Price is for a complete set of knobs.
A. Knobs for Astro-Tech (also GSO, iOptron, MallinCam, Orion, TPO) 6" f/9 Ritchey-Crétien Secondary
Part: AT6RC
Fits: Astro-Tech, GSO, iOptron, MallinCam, Orion (US), and TPO 6" f/9 RCT secondary (solid or truss-tube)
Knobs: Black plastic, 16 mm (5/8”) diameter
Threads: Stainless steel
Notes:
- If the dust cover cannot be installed because of knob height, you can use a shower cap in its place.
- On some versions of this telescope, knobs may contact the secondary housing surface before the screws reach the secondary mirror assembly. Contact us using the link at the bottom of this page for a set of knobs with longer screws.
$27.95
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B. Knobs for Astro-Tech (also GSO, iOptron, MallinCam, Orion, TPO) 8" f/8 Ritchey-Crétien Secondary
Part: AT8RC
Fits: Astro-Tech, GSO, iOptron, MallinCam, Orion (US), and TPO 8" f/8 RCT secondary (solid or truss-tube)
Knobs: Black plastic, 16 mm (5/8”) diameter
Threads: Stainless steel
Notes:
- If the dust cover cannot be installed because of knob height, you can use a shower cap in its place.
$27.95
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C. Knobs for Astro-Tech (also GSO, iOptron, MallinCam, Orion, TPO) 10" f/8 Ritchey-Crétien Secondary
Part: AT10RC
Fits: Astro-Tech, GSO, iOptron, MallinCam, Orion (US), and TPO 10" f/8 RCT secondary (solid or truss-tube)
Knobs: Black plastic, 16 mm (5/8”) diameter
Threads: Stainless steel
Notes:
- The factory dust cover may contact the knobs when installed, but the cover will remain in place. If desired, a shower cap can be used as a substitute cover.
$27.95
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D. Knobs for Astro-Tech (also GSO, iOptron, MallinCam, Orion, TPO) 12" f/8 Ritchey-Crétien Secondary
Part: AT12RC
Fits: Astro-Tech, GSO, iOptron, MallinCam, Orion (US), and TPO 12" f/8 RCT secondary (solid or truss-tube)
Knobs: Black plastic, 16 mm (5/8”) diameter
Threads: Stainless steel
Notes:
- The factory dust cover will fit normally with Bob’s Knobs installed.
$27.95
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E. Knobs for Astro-Tech (also GSO, iOptron, MallinCam, Orion, TPO) 16" f/8 Ritchey-Crétien Truss-Tube Secondary
Part: AT16RC
Fits: Astro-Tech, GSO, iOptron, MallinCam, Orion (US), and TPO 16" f/8 RCT truss-tube secondary
Knobs: Black plastic, 16 mm (5/8”) diameter
Threads: Stainless steel
$27.95