AstroPics

Astrophotography is as much an art as it is a science, where capturing clear, detailed images of celestial bodies requires precision, patience, and the right equipment. One of the critical techniques for achieving high-quality images is autoguiding. Here's a comprehensive guide on how to get started with autoguiding in your astrophotography setup.

What is Autoguiding?

Autoguiding is a method used to correct for the minute tracking errors inherent in even the best telescope mounts. By continuously adjusting the mount's tracking, autoguiding ensures that stars remain pinpoint over long exposure times, thus preventing star trails and capturing sharp, detailed images of galaxies, nebulae, and other deep-sky objects.

Equipment Needed

Telescope Mount: Preferably with a good periodic error correction (PEC) for better initial tracking.

Autoguider Camera: A sensitive camera designed for real-time star tracking. Examples include the QHY5II, ASI120MM, or similar.

Guide Scope or Off-Axis Guider (OAG): An additional small telescope or a device that splits off a portion of the light path from your main imaging setup.

Autoguiding Software: Programs like PHD2, Maxim DL, or software provided by the camera manufacturer.

Laptop/Computer: To run the autoguiding software.

Steps to Set Up Autoguiding

1. Align Your Mount

Polar Alignment: Ensure your mount is well-aligned with the celestial pole. The better the alignment, the less work your autoguider will need to do.

Balance: Properly balance your mount in both axes to prevent drift.

2. Connect the Equipment

Guide Scope or OAG: Attach your guide scope parallel to your main imaging scope, or use an OAG mounted on your imaging scope.

Autoguider Camera: Connect the camera to the guide scope or OAG. Ensure it's securely fastened and the guide star is in focus.

Software: Install and open your autoguiding software, connect your autoguider camera, and ensure it's recognized by the software.

3. Initial Setup in Software

Camera Settings: Adjust the exposure time for capturing guide stars. Typically, a few seconds are enough for bright stars.

Calibration: Most software requires a calibration step where the mount is moved in RA and Dec to determine correction rates. This involves:

Selecting a Guide Star: Choose a bright, isolated star for guiding.

Calibration Run: The software will move the mount in small steps to map out tracking corrections needed.

4. Start Guiding

Begin Autoguiding: After calibration, start guiding. The software will now monitor the guide star and send corrections to your mount if the star drifts.

Monitor: Keep an eye on the guiding graph for spikes or trends which might indicate issues like wind, balance problems, or mount errors.

5. Troubleshooting Common Issues

Star Drift: Recalibrate or check if your mount needs balancing.

Aggressive Corrections: If the mount is over-correcting, increase the "dead zone" or smoothing in your software settings.

Backlash: Adjust backlash settings in your mount's software if corrections are inconsistent.

6. Long Exposure Imaging

With autoguiding active, you can now safely take long exposures. Remember to:

Focus: Ensure your main imaging camera is well-focused.

Exposure: Start with shorter exposures to check for guiding accuracy before going long.

Conclusion

Autoguiding significantly enhances the quality of astrophotography by allowing extended exposure times without star trails. While the setup might seem daunting at first, with practice, autoguiding becomes an invaluable part of your imaging routine. Remember, perfecting your guiding technique is an iterative process where each session teaches you how to better your setup. Happy imaging!

John Ramdenee