Explore Scientific ED127 Robofocus Installation – Part 1

After lots of glowing recommendations, I decided to buy a Technical Innovations Robofocus for my Explore Scientific ED127 telescope and its stock Crayford focuser. Together with my astrophotography computer and camera, this should let my scope automatically focus itself with much better accuracy than I ever could.

I dug through their website, but didn’t see an Explore Scientific installation example and I couldn’t find one after quite a few online searches either.

I sent Technical Innovations an email asking if the Robofocus would fit my scope.  They replied back asking for a photo of the bottom of my scope’s focuser and the diameter of the focus knob shaft (it’s 0.158″ on the single-knob side).  After sending that info, they told me they could send a Robofocus with brackets that would work.

A few days after ordering, my Robofocus showed up.  They sent two identical mounting brackets.  With probably thousands of possible focusers out there, the Robofocus manual didn’t have specific installation text or photos for my scope.  I did a little more searching online and still didn’t find an example of a Robofocus/Explore Scientific ED127 combo.  So, I dove in.

There doesn’t appear to be a “perfect” place to anchor the mounting bracket on my existing focuser.  The best place with existing bolt holes looks like the bottom of the focus knob assembly.  I took off the single-knob and slipped the Robofocus into place.  A couple of bends later, the once-flat mounting bracket fit flush to the bottom of the focus knob assembly and the Robofocus’ mounting holes.

Here’s the bent mounting bracket.


Here’s the bracket & Robofocus in place on the scope.




The only down side to this mounting bracket location is that the bolt on the bottom of the focus knob assembly is really small.  Technical Innovations says in their FAQ that you can attach the mount to the scope using “Very High Bond” tape.  3M makes Very High Bond (VHB) tape that should work.  I’ve also heard of several people using 3M’s Command brand of double sided tape.  This tape is commonly used to hang hooks on walls, doors and other similar applications.  Since 3M Command tape is available almost everywhere, I’ll try that first.  I probably have some in the garage…

Check out part 2 of this post here: Explore Scientific ED127 Robofocus Installation – Part 2


  • Very clear photos. Thanks for being the leader in this experiment. I hope to do the same soon.

  • Bryan:
    I’m trying to install the Robofocus on my ES 127 and found your page really useful. I wouldn’t have been able to figure out for myself how to attach the mounting bracket to the scope. The question I had for you was regarding the motor attachement. When you say you took of the single knob and put the motor in place, did it attache securely to the focus knob shaft. Mine seems to sit loosely in the adaptor (the focus knob shaft)and I wonder what I may be doing wrong. I wonder if you have any thoughts.

  • @Khavar – When I ordered my Robofocus direct from the company, they asked me for the diameter of that shaft. The brass adapter they sent me that attaches the Robofocus shaft to the telescope’s focuser shaft fits great on both sides. The Focuser shaft is pretty small (0.158″). You may have an adapter that is too big. I recommend calling the company directly since this isn’t listed as one of their standard scope installations. They’ve been very helpful to me.

    @Robert – You’re welcome. Good luck!

    • Bryan: I am really mechanically challenged. I followed the instructions and attached the bracket to the bottom with screws instead of tape.it just didn’t seem secure and the motor would wobble when in use. So I bought a Moonlite CFL focuser which has the motor fixed to the focusing shaft and the focuses and aesthetically a beautiful and well constructed piece of equipment.

      I am impressed with the Robofocus and how wonderful focusing becomes when you have done it a few times. One question I had for you was how you power the Robofocus in the field. Do you use an investor (DC to AC) or do you use a cigarette lighter adaptor for your 12v battery? If its the battery,is it regulated. I attached it to a 12v 5A outlet on my battery and it powered on fine but wonder if its safe to do so for extended periods of time?

      • Khavar- I have a large 12V battery that I use when I’m in the field (it’s a Group 27-sized deep cycle RV battery…cost about $130). I have three separate 12V cigarette lighter adapters that I connect to it. From those, I power my SBIG camera, telescope and the Robofocus. The camera’s cooling is usually running between 50-80% all night and I just leave the Robofocus powered on. I have an inverter that I connect to my truck’s battery that powers my laptop. Using this setup, I haven’t had any trouble at all with power.

        Just to make sure everything is ready each night, I charge the batteries during the day. To charge the car battery, I just run the truck for a few hours. How I charge the big telescope battery depends on if I bring my generator. If I bring my generator, I plug in a BatteryMinder charger (model number 12248) to the generator. Using that charger, I can charge at 8 amps – which tops off the battery pretty quickly. If I don’t have a generator (I’ve only done this once), I run my truck, connect an inverter to my truck battery, and then charge using the BatteryMinder at 2A. The only downside to that method that I’ve found is that you have to charge all day. A more powerful inverter would fix that.

        I’ve read online that some people just jumper cables to their car battery and charging it by running their car. There are some reports online of this method putting extra wear & tear on their cars’ alternators. I’ve done this once or twice and haven’t had any issues, but I’ve always done that with a truck with a heavy duty alternator (bigger alternators typically come with towing packages). I also let my car battery charge up before connecting another battery to it just to make sure the alternator isn’t working too hard.

        In general, I try to use DC whenever possible. Most telescope equipment is powered using DC. Using an inverter to convert battery power (DC) to AC power so that you can use an AC adapter for your equipment wastes a LOT of power. If you power things directly with DC, you’ll use less power each night.

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