Bob's Knobs Celestron C5 Metric Collimation Knobs
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Bob's Knobs Celestron C5 Metric Collimation Knobs

  (2 Reviews)
✓ 2 year warranty


1x in stock shipped 1-2 working days

About this product

Model:  bk_c5_met_bo
Part Number:  C5metBO

Bob's Knobs are the BEST option for tool-free collimation.

Simple to fit and easy to use.

Collimate your telescope without an Allen key or screwdriver!

Instructions are supplied but can also be found online as well as useful FAQ.

Images are representative and may not show the exact knob size / threads.

IMPORTANT: Please ensure the Bob's knobs threads and factory screw threads match before installation.

5" SCT f/10 Metric

Part: C5metBO (black oxide steel); C5metSS (stainless steel)
Fits: Celestron 5” (13 cm) f/10 SCT (C5, NexStar 5SE, Omni 127) with black Phillips factory collimation screws. These screws have metric threads. Will not fit scopes with silver factory collimation screws (see Item A above).

Knobs: Black oxide steel (black) or stainless steel (silver), 12 mm (1/2”) diameter
Threads: Black oxide or stainless steel


  1. These knobs will fit only 2006 and later C5 models that have black Phillips factory collimation screws. All C5 models made prior to 2006 and all post-2006 models with black Allen or silver factory collimation screws require C5 standard knobs (Item A above). Check that our screw threads match the factory screw threads before installing.
  2. Black oxide steel (shown in photo) is for dry environments. Lightly oil the knobs periodically as an anti-corrosion measure. Stainless steel provides better corrosion protection in coastal or high humidity areas, or in places where dew or other condensation is common.
  3. The factory dust cover will fit normally with Bob's Knobs installed.
  4. Some telescope versions have a small plastic cover over the factory collimation screws. This cover must be removed and set aside when Bob's Knobs are installed. The cover is cosmetic only and will not affect operation of the scope.

Customer reviews

Average Rating (2 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
Necessary accessory for all reflectors.
04 July 2023  | 

I have Bob's Knobs on my other reflectors and find them to be both - massive convenience and time saving accessory.
My little C5 was due to its own one day and since opportunity presented itself now with purchase of other items from FLO (delivery to the Republic within 24 hours, just great service as usual) a set arrived.
Installation took no more then 5 minutes, followed by re-collimation using artificial star. Later that night I dialled collimation perfectly using Altair and it was a pleasure to work on this scope without screwdriver just fingers.
Not to mention I finally was able to get it perfectly collimated! After few sessions C5 holds collimation perfectly, but even if I needed to touch up on it - no more manipulation with screwdriver around corrector plate in the darkness, what's not to like here?
Do yourself a favour and get BKs for your reflector too.

Rating (max 5):  
ease of use
22 August 2022  | 

These are easier to use to collimate than using a screwdriver in the dark


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