An obvious problem with the use of a telescope is getting the former to point at the proper part of the sky which you intend to observe, or vice versa when you spot something interesting and wish to record the exact location. While all of this can be done manually with some trouble, there’s a lot to be said for automating this process. Unfortunately these Digital Setting Circles (DSC) features are not cheap even as add-on, which is why [Vladimir Atehortúa] created DobsonianDSC as a low-cost DIY solution.
As the name suggests, this project is based around a Dobsonian-style telescope: Newtonian tube with simple altazimuth base. Aside from the mechanical construction, this system uses an ESP32 as its controller along with two rotary encoders, with the simple circuit detailed in a build guide. The firmware for the ESP32 is written in the Arduino C dialect, and a guide for flashing the ESP32 with the Arduino IDE and connecting it to the WLAN is provided as well.
After setup, the resulting telescope system can be used either via WiFi or Bluetooth from existing apps such as SkySafari that support the ‘Basic Encoding System’. An initial calibration is required, but after that you should have a telescope that works in concert with SkySafari or similar to automate this tedious part of astronomy away.
Obviously this is not a ready-to-install system, as every telescope is shaped and sized differently, but inspiration for mounting solutions is provided as well.
> While all of this can be done manually with some trouble,
uhh, what? If you know what you’re doing a printed setting circle and an angle finder is all you need.
I have done that, but calibration is a nuisance. You have to point to several objects and then type the coordinates from the paper circles into the software, unless you can ensure very level ground and alignment to North.
This is an alt-az scope, so catalogued star positions have to be converted with a lot of trigonometry and the results are only good for a few seconds before the star has moved significantly.
I have a similar telescope, while a DSC is nice, I’ve been want to motorize it. However, to get the movement resolution I want I need something like a 9000000:1 drive, which seems tricky to DIY in a compact form factor. I might just end up buying a used motorized mount, but maybe a worm gear driven by a series of planetary gearboxes might work (although not so compact).
90000000:1 means that the motor has to rotate 7 times to move the telescope an arcsecond and has to spin at over 6000 RPM just to keep up with the sky.
You probably want something like a few arcseconds to be the quantum of motion on your motor (e.g. a quarter-step if you are using steppers). Astrophotography has tighter tolerances than looking through an eyepiece.
Possibly I got my (gotta-start-somewhere) specs from a much more (too) high end motorized mount that claimed 0.1436 arc sec tracking precision. If I use a stepper motor and substepping works (which I’ve heard might be a problem for driving something like that), then I may be able to get well below 1:1000000, which still seems like a lot, but more do able.
More knowledge of, and personal experience with, amateur astronomy would have been nice, as would have been a more detailed, more in-depth article.
Dobsonians are not for astrophotography.
NO telescope using an alt-az mount is for astrophotography. Except if you are a masochist.
Isn’t the idea that you have a computer do the masochistic work of converting the polar coordinates into alt-az?
You also have to rotate the eyepiece with an alt-az
mount in order to keep all the stars in the same position for long exposures. That’s something you get for free with an equatorial mount.
“…NO telescope using an alt-az mount is for astrophotography. Except if you are a masochist.”
Correction: not even for a masochist.
EQ mounts limit you in scope size though. There are simple workarounds for alt-az, like EQ platforms, which can get you decent exposure times while retaining the light weight and simplicity of alt-az:
http://www.equatorialplatforms.com/
“EQ mounts limit you in scope size though…
Indeed they do; and it’s a fact that most people wanting to get started in amateur astronomy are completely oblivious to the fact that the mount is at least as important as the ‘scope—and a good one (read that as “one which you really DO need, if you are serious”) oftentimes just as expensive, if nor moreso.
There’s no way an individual could afford an equatorial mount for the super-large Dobsonians shown on E-P’s website—or for a Dobsonian of even half those sizes.
Great information; thanks for bringing E-P to our attention. Very worthwhile visiting their site if for nothing more than the astrophotography photos. Simply outstanding.
All the best to them.
I’ve thought about building a motordrive for mine, with a drive that would also rotate the camera in the eyepiece.