Bob's Knobs Celestron 8'' EdgeHD Collimation Knobs
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Bob's Knobs Celestron 8" EdgeHD Collimation Knobs

  (6 Reviews)
✓ 2 year warranty


8x in stock shipped 1-2 working days

About this product

Model:  bk_c8_edge_met_bo
Part Number:  C8edgBO

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.

Knobs for C8 f/10 Secondary with EdgeHD Optics

Part: C8edgBO (black oxide steel); C8edgSS (stainless steel)
Fits: Celestron 8” (20 cm) f/10 SCT with Fastar secondary and EdgeHD optics.

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 the Celestron 8” SCT with Fastar secondary and EdgeHD optics. These telescopes are marked “EDGEHD OPTICS” on the corrector ring. Do not use these knobs on the non-EdgeHD Fastar secondary; the screws on these knobs are too long. Be sure to check that the thread length on our knobs matches the thread length on the factory collimation screws.
  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.

Customer reviews

Average Rating (6 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
Bob's Knobs Celestron 8" EdgeHD Collimation Knobs
10 October 2022  | 

A life saver

Rating (max 5):  
Bob's Excellent Knob's
23 September 2022  | 

I have heard about Bob and his magnificent knobs for a while and whilst rummaging around in the dark with a screwdriver next to my SCT I thought why not? Fitting was easy as long as you follow the instructions which, in brief explain how you should replace one screw at a time.
Once in place, I did a rough collimation (as per the instructions_ by looking down the tube and observing the mirror reflections before using a “Hubble Optics 5-Star Artificial Star” from FLO to collimate better on a defocussed light source. This had the added value of giving me a “feel” for how the adjustments work so when I fine-tune on a star it should be more intuitive.
So, yes cant recommend them enough. I know with some users these things are marmite (either love it or hate it) but I cant think of anything better than not waving a sharp scratchy screw driver in the dark next to a corrector plate

Rating (max 5):  
Great Experience Superfast Delivery
05 July 2022  | 

Lynx Heavy Duty Cable, Some USB Leads and Bobs Knobs delivered well packed and fast from the UK to Caves Beach NSW in 7 days flat. Very impressed indeed

Rating (max 5):  
Make collimating easy
02 March 2020  | 

Very easy to use, best Collimation I have got in years. Should have got som earlier.

Rating (max 5):  
Thanks Bob!
18 November 2018  | 

The fear of using a sharp screwdriver at night on my 8" EdgeHD front lens has gone, they may only be simple knobs but they really work. I collimated my EdgeHD within 5 mins first time, I had no idea it was so out, real improvement to my astro photography made possible with these and I will now check this every time I set up. A bit expensive maybe, a quality item with real usefulness - double yes. Thanks Bob (wherever you are!) and FLO of course.

Rating (max 5):  
Perfect Engineering
16 April 2018  | 

This is a quality product that does what it should do. Very rapid service from FLO as always


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