Bob's Knobs

Fits: Zhumell Z8, Z10, and Z12 telescopes

Most mass-produced Newtonian telescopes from Celestron, GSO, Hardin Optical, Meade, Orion, Synta, and Zhumell use one of the secondary mirror configurations shown on this page. The photographs and descriptions below will help you determine which knobs to

Part: C14stdphi
Fits: Celestron 14” (36 cm) f/11 SCT versions with factory Phillips collimation screws with standard threads, with or without Fastar.

Part: M8-6
Fits: Meade 8” (20 cm) f/10 SCT versions with six screws on the secondary housing (LX90, LX200, LX200ACF, LX200R, LS-8 SC and ACF, LT-8 SC and ACF, others). The inner screws are for collimation.

Part: M8-4
Fits: Meade 8” (20 cm) f/10 SCT versions with four screws on the secondary housing (LX90, LX200, others).
Knobs: Black plastic, 13 mm (1/2”) diameter
Threads: Black anodized aluminum alloy

Part: M8-3
Fits: Meade 8” (20 cm) f/10 SCT versions with three screws on the secondary housing (2080, LX5, LX10, LX50, LX90, LX100, LX200, others)

M14-6e

Meade 12” (30 cm) f/10 SCT versions with three screws or four screws on the secondary housing

Meade 10” (25 cm) f/10 SCT versions with three screws on the secondary housing (2120, LX10, LX50, LX90, LX100, LX200, others)

M10-6 Meade 10" f/10 SCT 6-Screw Secondary

Part: C9.25std
Fits: Celestron 9.25” (23.5 cm) f/10 SCT versions with standard collimation screw threads (not for CPC 925 or EdgeHD).

Part: C8std
Fits: Celestron 8” (20 cm) f/10 post-1980 SCT with factory Allen or silver Phillips collimation screws, with or without Fastar secondary with silver collimation screws (C8 black, or gray; Ultima 2000; NexStar 8; others). This includes the pos

We offer knobs for the Celestron 5” Schmidt-Cassegrain secondary with either standard or metric collimation screws in the f/10 and rare f/6 versions.

Part: C11std
Fits: Celestron 11” (28 cm) f/10 SCT versions (metal or carbon fiber tube) with flat secondary housing and standard collimation screw threads (not for CPC 1100 or EdgeHD).

Part: C11stdfst
Fits: Celestron 11” (28 cm) f/10 SCT versions (metal or carbon fiber tube) with standard thread factory collimation screws and "Trifid" rotary cover Fastar secondary housing. Factory collimation screws are silver Phillips. These knobs wil