Remote focus attachment for Newtonian telescope

thingiverse

This is an advanced attachment designed specifically for an 8-inch Newtonian telescope. It's most useful when paired with a PC-controlled camera that enables you to focus accurately without physically being near the telescope. With suitable software, automated focusing becomes possible as well. The attachment is split into two parts - one attaches to the focuser base while the other holds the servo motor in place. A small cup connects the servo's axle to the focuser knob, making it easy to switch between manual and automatic modes or adjust focus range by removing the servo-holding part. The design is highly adjustable, allowing you to easily adapt it for use with different sizes of telescopes, focusers, and servos. The RC servo motor comes in handy, providing a consistent and repeatable focus (as limited by mechanical constraints - approaching from one side always helps). It operates within the half-turn limit of the focuser's screw, which suffices for most situations. For a more direct approach, you can repurpose an inexpensive RC servo tester (available at around $5) as your controller, connecting it to a USB port's 5V line. For even more complex control setups, using tiny Arduinos with PCs is an option. An alternative method involves stripping down the servo motor and reusing its internal parts - specifically, the motor and gears. Without any positional feedback in this setup, you can operate freely within unlimited travel range, although adjustments become trickier. Controlling it becomes feasible via a simple 3-way DPDT switch ideally equipped with springs to handle motion on both sides. To extend your control capabilities even further, consider replacing traditional servos with continuous rotation ones like the one offered by Pololu (https://www.pololu.com/product/2149) though this path remains unexplored here for the time being. Components you will need: - One strong RC servo model HK15328A including mounting accessories. - Five 5mm long screws (with three working fine). - Three countersunk M2.5 screws accompanied by nuts or even a soft foam pad and glue for a smoother experience with the knob-to-servo adapter.