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Bob's Knobs Collimation Knobs for Celestron 8" f/10 Secondary w/ EdgeHD

Bob's Knobs Collimation Knobs for Celestron 8" SCT f/10 w/ EdgeHD Optics

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    Bob's Knobs
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    Estimated Arrival: Between Feb 27 and Mar 05. *ETA to USA Only

    Shipping & Returns: Ships for free. Satisfaction guaranteed 30 day return policy.


    We offer knobs for all versions of the Celestron 8” f/10 Schmidt-Cassegrain secondary with either standard or metric collimation screws, including Fastar, non-Fastar, and the classic orange tube. Select knobs for your telescope from the list below. Please use care to select the correct knobs for your telescope. Each knob set is different and they are not interchangeable. Price is for a complete set of knobs.

    Fits: Celestron 8” (20 cm) f/10 SCT with Fastar secondary and EdgeHD optics.


    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 knob top and knob serrations 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. The Celestron 8” SCT uses either standard 6-32 or metric M3 collimation screws. Allensilver Phillips, and set-style factory collimation screws have standard threads. Most black Phillips screws are metric. See our hints and our Celestron technical paper.for more information. If you order knobs with the wrong screws, contact us for return instructions.



    Black oxide steel (black) or stainless steel (silver), 12mm (1/2") diameter


    Black oxide or stainless steel


    We know that once you've placed your order, you are anxious to receive it! We make every effort to get your order shipped out to you as quickly as possible.

    As soon as you place your order, you will receive an order confirmation e-mail. This means that we have received your order in our system and pre-authorized your credit card for the purchase. We will process the charges to your credit card and your order will ship within five business days from the date of your order. We will send you tracking information within 24 hours of your order leaving the warehouse to the e-mail address you provided when checking out.  If you do not receive tracking information from us within six business days of your order, feel free to follow up with us at

    Standard shipping time in the US is between 3-5 business days, though it can vary slightly depending on the destination. We typically For updates on your shipment you can enter your tracking number here.

    We distribute nationwide via UPS and Fedex. Unfortunately, at this time we are not able to provide expedited or international shipping.