Working with What You Have (astrophotography)

After reading my conundrum with my astrophotography equipment, I gathered what I had and looked for a solution.

Since I’m in no way able to afford a huge tricked out scope (we got a great deal on my 8″ LX10 on craigslist!) I’m sticking with what I have. Again, there’s a tracker on my scope but it is basically a barn door tracker. It is slightly more sophisticated though, it has a controller with “North, South, East, and West” buttons on it. As long as it is perfectly polar aligned (I’ll talk about this later) all I have to do is turn it on and it’ll automatically track whatever the scope is pointed at (this is typical barn door behavior) but if I want to drive the scope to look at something to the east, I hold down the “East” button on the controller, and it will DOUBLE the speed of the motor… making 1 revolution in 12 hours instead of 24. Wow right! Not so speedy. Well, it gets better. If I want to look at something West of my current object, holding the “West” button turns the motor off completely. The telescope then simply waits for the earth to spin until that object is within view. The North and South buttons work a little differently, the scope doesn’t move either of these directions unless a button is pushed. When it is, it turns on a motor that moves **Just as slow as the tracker motor.** It can also only move in a particular North/South direction until a screw on the mount bottoms out. This limits the number of degrees of rotation I can do North to South. Typically, I set it up so that when I start viewing, I’m in the middle of the screw, which gives me just as much leeway North as South, but halves the total amount I can move the scope in any one particular direction.

All this means that there’s no way I can whip this thing around to look at whatever I want automatically like GoTo systems do.  I’ll have to unlock the clutches on each axis, then swing it manually to point at an object of interest, then lock the clutches down again and let the motors take over. I’m fine with that, but how do I know where things are in the sky? I’m not great at memorizing locations of stars and DSOs. My solution is to use a PushTo setup. A PushTo is for dumb telescopes. Basically, you attach it to your scope and it tracks where you are manually moving it to point. The best solution I’ve found for this is an app called Skeye.  It is like google sky map, except it was designed so you can mount your tablet or phone to your OTA (Optical Tube Assembly… or Tube where your mirrors and lenses are). I’ll do a tutorial on how to setup and use this as well. For now, check out this guy’s setup.

So I can find objects in the sky, how do I take good photos of them? Due to budget (none really) I have to work with what I have, I first need to make sure that:
1. I am relatively well alighed with true North. (Not perfectly aligned, but close enough and I can do this quick and dirty).
2. I manually move the scope to point at what I want to look at. (This is easy enough).
3. Use a computer to automatically control the direction of the scope for long periods of time.

That last one is a doosey. And so that’s where my adventure began a few years back. I joined the yahoo support group for LX10 owners. Luckily, some of those guys have figured out different ways to hack together store-bought systems with their LX10s. Many of them were a bit too advanced for me (I don’t own a machine shop nor and I spending several hundred dollars on buying another telescope brand’s trackers and rigging it to my system in the hopes that I don’t fry it…) A guy named gt_keys had already been looking at a simple solution to connect an LX10 to computer-based guidance systems via an arduino connection. I like this idea because it can be used with multiple kinds of computer software.

The arduino hardware and code was developed by yahoo user gt_keys in Spring 2013. You can find his threads on the LX10 yahoo group; specifically, these files come from the files section.  I’ll ask if he would put it on GitHub, or if he minds if I do so you can download it.

He has also developed a RaspberryPi version as well that seems to be more capable. Seeing as how the LX-10 is limited in the Dec and Right Ascension speeds, this arduino implementation will work fine for most things though you need to be connected to a computer of some type.

This requires a number of software packages to be installed:

1. Arduino IDE… so you can download the firmware
2. PHD Guidance 2 which tracks video of a star then send commands to a scope
3. ASCOM platform which are a middle-man layer between PHD2 and whatever telescope driver you are using
4. Meade Classic and Autostar 1 drivers (See below)
5. Should you want to control your actual camera DSLR or astronomy webcam, some software for this. It will vary based on your particular camera, but FireCapture is one I’ve heard of for astronomy cameras like the ZWO brand or Celestion NexImage5 which I hear is good. As for a Canon, Nikon, or other brand, you can google around and find something to drive them. I’m testing out DSLRDashboard which supports many Canon and Nikon cameras.

So the hardware flow looks like this: You’ll have a USB webcam attached to your sighting scope which will feed data to a program called PHD Guider 2. See my post for how to attach a USB camera to your sighting scope. This must also have the ASCOM drivers installed which know how to talk to different telescope systems. Specifically we will need the “Meade Classic and Autostar 1” driver. (I can’t remember exactly which driver it is on the ASCOM site, but it is either this one or this one). This can be found in the settings menu of PHD2. I went through the “new equipment wizard” in PHD2 to create a group of settings for my equipment. Again, since the LX-10’s hardware is so limited, there isn’t much to enter really. There is no focus knob (though if you add one, gt_key’s arduino code seems to be able to handle it).

PHD2 will take the image from the webcam attached to your site scope and allow you to specify a particular star in the field. Once you begin tracking, PHD2 looks at how many pixels the star in your image has moved, then send the appropriate commands to move to the ASCOM drivers. These translate that command into whatever command your scope hardware requires. For instance, you might have an autoguiding Orion scope. There’s drivers for all of that stuff. In our case, the Meade LX10 doesn’t have a computer language, so gt_keys chose to use the classic Meade and Autostar 1 command set.

The ASCOM drivers send the message over your USB serial port to the arduino. gt_keys’s code reads in those commands and basically pushes the buttons on the LX-10’s hand controller electrically. The motors on the LX10 move very slow. It is literally a barn door contraption, moving a full 360 degrees in 24 hours, and if you want to drive the telescope the other direction, it just turns the motor off and waits for the earth to spin to the point you want to move to. This means that for you to get good long exposures or to track planets well enough, you have to get a relatively close polar alignment on your scope before you start. More on this in another post.
Hardware Setup:
Firstly, build the schematic as shown. I used a green relay board from Seeed studios.

Secondly, before you flash the firmware to the arduino, you have to change a value to make the hand-held controller to work. This is on line 56. You must change “const int hcontrol = 0;” to “const int hcontrol = 1;” Otherwise you cannot test this thing unless you have it all connected up to the computer, getting ASCOM commands which are generated from the PHD2 program.
Other software and options:
How to guide mount PHD:

As an alternative to PHD Guider 2, (PHD2) you can try AstroTortilla. Though I’ve never tried it,  here’s a tutorial for how to use it.
I have not tried these out, however I’ve seen them recommended several times. Comment and let me know if you love or hate any of these:
AstroImageJ is ImageJ for astronomy. ImageJ is a image processing program for scientific use that’s open sourced, Java-based and encourages lots of plugins, extensions, and macros to be built.

Astronomy.net can help calibrate your images through a web app. Really awesome to see other peoples’ shots as well. You can also have it pick out and name stars in images you upload. It is really cool. There’s a bot on reddit’s astro subreddits that automatically does this and posts the results if you submit images to that reddit. Here’s the bot’s feed  and here’s an “Ask Me anything” AMA with the author.  Oh, and the source code is completely open course too so you can hack on it if you want.