Autoguiding a telescope for deep-sky imaging
Basic Autoguiding for Astrophotography Made Simple
Autoguiding is something that can be a bit daunting when you are a beginner to astrophotography. The process that takes place while guiding a telescope mount is an impressive technical feat for someone like myself, with no background in electrical engineering. It’s really not that hard, and it makes a big difference in your images.
Longer exposures mean that more light is recorded in a single frame. More light means the ability to capture fainter nebulae, galaxies, and all of the other amazing deep-sky objects that are just waiting for you to find them.
The reason autoguiding is so important is because images exposed for 2 minutes or longer will start to show star trailing without guiding. This is not so much of an issue with more sophisticated (and expensive) mounts, but it is with humble mounts such as the SkyWatcher HEQ5 that I own. Autoguiding will take your image exposures from 1 minute to 5 minutes or longer. This can really make a dramatic impact on the detail of your deep-sky objects.
Just because the actions taking place are advanced, doesn’t mean that your technical skills need to be. Today’s tools at the hand of backyard astrophotographers make the entire process a pleasant experience.
What you need to start Autoguiding
The basic equipment needed to accomplish a successful night of autoguiding are a separate guiding telescope and a guide camera. The guide telescope rides atop your primary imaging telescope and is usually much smaller. The autoguiding camera is connected to this smaller telescope and your computer.
The main objective for this equipment is to focus and lock onto a star in the guide telescope’s field of view. The camera takes continuous short exposure frames and displays the “live” video feed on your computer screen.
The guide camera and your mount communicate with each other to maintain a lock on your target. This is accomplished by using a great piece of free software developed by Stark Labs.
In February 2017, I started experimenting using a new autoguiding camera. The Altair Astro GPCAM2 AR0130 Mono is an excellent choice for astro-imagers on a budget. My early results were promising, and I may upgrade to this system in the near future.
By using an autoguiding software such as PHD2 Guiding, our computer can communicate with the telescope mount. PHD2 Guiding is the successor to PHD Guiding, which I used for several years before upgrading to PHD2. PHD stands for “Push Here Dummy”, and it very easy to use, once everything is setup properly.
PHD2 Guiding includes a user interface that allows you to enter in your specific connection type and autoguiding camera model. Currently, I use a Meade DSI Pro II camera with an Orion 50mm Guide Scope. This combination has worked well for me, and I often recommend the Orion 50mm guide scope to beginners looking to start autoguding.
- Attach 50mm Guide Scope to Primary Imaging Telescope
- Install Meade DSI CCD camera to the guide scope
- Connect PHD2 Guiding to Mount via GPUSB adapter
- Connect Meade DSI CCD to Computer via USB
- Run PHD2 Guiding
- Calibrate on Star within field of target DSO
- Run Dither function on BackyardEOS using PHD2
I use a 1-second refresh rate on the Meade DSI CCD camera to display a small number of stars within the field of view. It is important to make sure that the guide scope is properly focused to ensure accurate star tracking. Once the calibration process has been successfully completed, I like to press “stop” on the calibration star guiding. I then start the live-view up again, and begin autoguiding on another star in the frame. When PHD is running, I usually open on the “graph” window to monitor the accuracy of the tracking.
Watch me Autoguide on the Trifid Nebula
The Orion Magnificent Mini Autoguider Package is probably the best way to start autoguiding right away. This package includes the camera, the guidescope, and the mount, all for a reasonable price. In the future, I will be testing some different guiding equipment and methods. As always, I am happy to share my results.
Please consider visiting the Learn Astrophotography section of this site to explore my techniques during real life situations in the backyard.