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Bob's Knobs Collimation Knobs For Celestron 8" SCT F/10 Post-1980 - Standard
Bob's Knobs Collimation Knobs For Celestron 8" SCT F/10 Post-1980 - Standard

Bob's Knobs Collimation Knobs for Celestron 8" SCT f/10 Post-1980 - Standard

Bob's Knobs
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Estimated Arrival: Between Oct 05 and Oct 11. *ETA to USA Only

Shipping & Returns: Satisfaction guaranteed 30 day return policy.


Bob's Knobs offers 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 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; many others). This includes the post-2005 orange-tube. Will NOT fit pre-1980 orange tube or most scopes with black Phillips factory collimation screws.


  1. These knobs will fit C8 models made prior to 2005 (except pre-1980 orange tube; see Item A above), and most post-2005 models with silver factory collimation screws.
  2. Most models with black Phillips factory collimation screws require C8 metric knobs (Item C below). However, a few post-2005 scopes have black Phillips collimation screws with standard threads. Here are some hints to help determine which screws your telescope has. Make sure the knob threads match the factory screw threads before installing the knobs.
  3. We provide spacers to raise the knobs slightly for easier use, but the spacers can be omitted if the knobs contact the inside of the full-aperture dust cover. Spacers are required for knobs installed on the Fastar secondary with silver collimation screws for proper clearance.
  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.
  5. 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 plastic, 13mm (1/2”) diameter


Black anodized aluminum alloy


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.