The Celestron C100ED refractor is an excellent telescope. However, owners have long complained of the poor quality of the telescope's stock R&P focuser as its weakest point. Complicating the matter further is the fact that the stock focuser screws into the rear of the telescope tube. Unlike 95% of the other telescopes in the market, the focuser does not bolt to the tube. For those looking to upgrade the focuser, the only alternative until recently was to upgrade to a competing Crayford focuser + adapter costing over $300 - over half the cost of the entire telescope itself!
However, with Agena's new coupling adapter for the Celestron C100ED, you can now attach the very affordable and excellent 86mm GSO Crayford focuser to the C100ED in a few minutes. Installation is easy - just unscrew the stock R&P focuser from the Celestron C100ED tube, screw this adapter into the tube in its place, slide the GSO focuser into this adapter, and bolt it to the adapter using three M4 screws (included with the adapter). The only tool you need to provide is a Philips (cross-head) screwdriver. This upgrade will turn your C100ED telescope into the little beauty it was meant to be.
This adapter will work with GSO's single or dual speed Crayford focusers that have an 86mm flange/base plate (focuser sold separately). It is precision CNC-machined from aluminum and anodized black to match the surface finish of the C80ED tube.
Relative to the stock R&P focuser, the GSO Dual-Speed Crayford/Agena Adapter combination will allow 22mm of additional in-focus travel which is a plus for imaging applications. On the flip side, our configuration will provide 7mm less of back-focus travel compared to the stock focuser but this is easily remedied with an extension tube, if necessary.
If you upgrade your stock C100ED focuser, note that you will loose the built-in finder base on the stock C100ED focuser body when you remove it. To use a finder, you will have to mount a finder bracket directly on the telescope tube, or you can mount it on the GSO focuser body using a special dovetail base (sold separately).
Important Note:- Before ordering this item, please make sure you can unscrew the stock focuser from your telescope tube. It can be very stiff on some C100ED telescopes due to poor machining of threads, and a couple of people have been unable to unscrew the original R&P focuser from their telescope.