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.
- Knobs with two different screw lengths are included. Try a shorter screw first. If the knob contacts the secondary housing, use longer screws instead. Base of the knob should be at least 1mm above the surface of the secondary housing.
$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) 14" f/8 Ritchey-Crétien Truss-Tube Secondary
Part: AT14RC
Fits: Astro-Tech, GSO, iOptron, MallinCam, Orion (US), and TPO 14" f/8 RCT truss-tube secondary
Knobs: Black plastic, 16 mm (5/8”) diameter
Threads: Stainless steel
Notes:
- The factory dust cover will fit normally with Bob’s Knobs installed.
- If the screws are too short to reach the secondary, 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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F. 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
Notes:
- The factory dust cover will fit normally with Bob’s Knobs installed.
$27.95
