How to Attach a Finder to your Crayford Focuser
In recent months, a number of customers have asked us for a solution to mount finders on their Crayford focusers. We are pleased to offer you a simple, elegant, and inexpensive solution via a modified Universal Finder Dovetail Base. This can be used to mount your red dot, multi-reticle, or larger conventional finder on single- or dual-speed GSO/Antares/Hardin/Burgess Crayford focusers that use an M4 screw to mount the dovetail base (Note: This will not work with William Optics telescopes which use an M5 screw).
The image below shows our standard GSO/Synta style dovetail base for finder brackets on the left. However, you cannot use this base directly on your Crayford focuser as the base will be obstructed by the focuser's adapter plate. On the right is a modified version of this same dovetail base. We've drilled two holes (silver) and you can now use one hole to mount this dovetail base on your Crayford focuser without hitting the focuser's adapter plate.
All GSO/Antares/Hardin/Burgess/William Optics Crayford focusers come with two mounting holes where you can attach a finder base. Normaly, these are not used and closed with a M4 (metric thread) set-screw. The image below shows these screws, with the one on the left partially drawn out for clarity. You can thus mount your finder on either side, depending on your preference.
Using a 2mm or 5/64" allen key, remove one of the set-screws completely, and attach the modified dovetail base using a M4 machine screw (included with the modified base) as shown in the photo below. You will not be able to use both the mounting holes. However, the attachment is very stable and will not slip or turn even though just one screw is used.
Slip in your GSO/Synta compatible finder bracket into the dovetail base and you are good to go. The photo below shows a GSO 50mm straight-through finder mounted on a dual-speed refractor focuser. You can also mount our GSO red dot finder, or right-angle finder in this manner.