Autoguiding: Enhance Your Astrophotography Skills

Autoguiding is a technique used in long-exposure astrophotography to accurately track celestial bodies, compensating for the Earth’s rotation. This approach ensures that stars appear as perfect points of light, rather than streaks or trails, even in very long exposures. By mastering autoguiding, you can capture sharper, clearer images that reveal the intricate details of our universe.

In this comprehensive guide, we will explain the science behind autoguiding, delve into its many benefits, and walk you through setting up and using an autoguiding system. So, whether you’re a seasoned stargazer or an astrophotography novice, this article aims to shed light on how autoguiding can enhance your celestial captures.

What is Autoguiding?

As the Earth spins on its axis, the stars appear to move across the sky. This can create beautiful star trails in photographs but can be a challenge when trying to capture detailed images of specific celestial objects. Autoguiding, a technique widely used in astrophotography, helps combat this issue.

Understanding Autoguiding

At its core, autoguiding is a system that allows your telescope to accurately follow celestial objects as they move across the sky, a process known as “tracking”. While all motorized telescope mounts provide a basic level of tracking, it’s often not precise enough for long-exposure astrophotography.

Autoguiding systems take tracking to the next level by using a secondary, smaller telescope (known as a guide scope) and a specialized camera (a guide camera). The guide camera continually takes short exposure shots of a chosen guide star and relays this information to the mount.

Image credit: Brandon Ghany on Flikr.
Camera: Canon T3i (stock / unmodified / unmodded DSLR)
Telescope: Explore Scientific ED80 f/6.0 Apochromatic Refractor (with ES field flattener)
Mount: Orion Sirius EQ-G
Guide scope: Svbony 50mm f/4.0 Guide Scope
Guide camera: Orion StarShoot AutoGuider
Bortle Class 6 (Charlottesville, VA)

The Science Behind Autoguiding

Autoguiding’s prowess comes from its real-time adjustments. By continually monitoring a guide star, the autoguiding system can detect even the smallest movement caused by imperfect tracking or atmospheric disturbance. The system then sends corrections to the telescope’s mount, adjusting its position to keep the guide star – and therefore your main target – perfectly in place. This meticulous tracking provides the stability needed for long-exposure astrophotography, ensuring your images are as crisp and detailed as possible.

Components of an Autoguiding System

An autoguiding system consists of three main components:

  1. Guide Scope: A small secondary telescope that rides along with your main telescope. Its job is to keep an eye on a particular guide star.
  2. Guide Camera: Attached to the guide scope, this camera takes continuous short-exposure shots of the guide star.
  3. Autoguiding Software: This software analyzes the guide star’s position in each frame and sends any necessary corrections to the mount.

Autoguiding, with its careful calibration and real-time corrections, can significantly enhance the quality of your astrophotography. It’s a worthwhile investment for anyone looking to take their celestial captures to the next level.

Benefits of Autoguiding in Astrophotography

Autoguiding can seem like an overwhelming concept at first, especially when you’re just starting your astrophotography journey. However, the benefits of mastering this technique far outweigh the initial learning curve.

Improved Image Quality

One of the main advantages of autoguiding is the noticeable improvement in image quality. By providing precise tracking, autoguiding eliminates the ‘star trailing’ effect in long-exposure images. It enables you to capture sharp, detailed photos that truly showcase the mesmerizing beauty of the cosmos.

Compensation for Gear Imperfections

Even the highest-quality telescope mounts aren’t perfect. Small errors known as ‘periodic errors’ can occur in the gears, which can affect tracking accuracy. Autoguiding compensates for these imperfections, constantly adjusting for any small movements to keep your target object centered.

Efficiency in Capturing Long-Exposure Shots

Without autoguiding, you may find yourself frequently adjusting and realigning your telescope to keep your target object in view, which can be especially tedious during long photography sessions. An autoguiding system automates this process, allowing you to capture long-exposure shots more efficiently. This makes autoguiding particularly important for deep sky imaging.

Autoguiding doesn’t just enhance your astrophotography skills; it also elevates the entire stargazing experience. It allows you to focus more on exploring the universe and less on constantly tweaking your equipment.

Setting Up Your Autoguiding System

Ready to dive into autoguiding? The first step is to set up your autoguiding system. This involves choosing the right equipment, connecting everything, and getting your settings just right.

Choosing the Right Guide Scope and Camera

Your guide scope and camera are crucial parts of your autoguiding system. The guide scope should be sturdy enough to hold the guide camera but light enough not to overburden your main telescope’s mount. When choosing a guide camera, look for one that’s sensitive enough to detect the guide star’s motion. A monochrome camera is a good option, as they’re typically more sensitive than their color counterparts.

Five guide scopes you might want to consider

NameEstimated PriceFocal LengthApertureFeatures
Meoptex 50mm Mini Guide Scope$75190mm50mmCheapest option, works with scopes up to 800mm focal length
Orion 50mm Mini Guide Scope$99162mm50mmAffordable option, works with scopes up to 1000mm focal length, includes dovetail base
Starwave 50mm Guide Scope$129242mm50mmSolid option, works with scopes up to 1200mm focal length, includes mounting rings and dovetail bar
Orion 60mm Guide Scope$169240mm60mmHigher quality option, works with scopes up to 1500mm focal length, includes mounting rings and dovetail bar
Sky-Watcher EVOGuide 50ED Guide Scope$349242mm50mmPremium option, doublet guide scope with FPL-53 glass, can also be used as a main imaging scope for widefield astroscapes
Note: Prices are estimates and will depend on where you buy from.
autoguiding. Orion 60mm Guide Scope
Orion 60mm Guide Scope

As for guide cameras, here are some options to consider:

NamePriceSensor SizePixel SizeFeatures
ASI120MM Mini Guide Camera or QHY 5L-II (equivalent)$149 (ZWO) or $159 (QHY)1/3″ CMOS (4.8×3.6 mm)3.75 micronsAffordable option, good for short focal length guide scopes, can also be used for lunar and planetary imaging
ASI290MM Mini Guide Camera or QHY 5-III-290 (equivalent)$299 (ZWO) or $329 (QHY)1/2.8″ CMOS (5.6×3.2 mm)2.9 micronsHigher quality option, good for longer focal length guide scopes, can also be used for lunar and planetary imaging
ASI178MM Mini Guide Camera or QHY 5-III-178 (equivalent)$349 (ZWO) or $369 (QHY)1/1.8″ CMOS (7.4×5 mm)2.4 micronsHighest quality option, good for longer focal length guide scopes, can also be used for lunar and planetary imaging
Note: Prices are estimates and will depend on where you buy from.
autoguiding. ZWO ASI290MM Mini USB 2.0 Monochrome Small Format CMOS Camera
ZWO ASI290MM Mini USB 2.0 Monochrome Small Format CMOS Camera

Connecting and Configuring Your Equipment

Once you’ve chosen your guide scope and camera, you’ll need to mount the guide scope to your main telescope and connect the guide camera to your computer. Your autoguiding software will use the images from the guide camera to track the guide star and send corrections to your mount.

With everything connected, you’ll need to configure your autoguiding software. This will involve selecting the right guide star, setting the exposure time for the guide camera, and adjusting the correction settings for your mount. Remember, each setup will require a bit of fine-tuning, so don’t be disheartened if you don’t get it perfect right away.

Setting up an autoguiding system can seem like a daunting task, but it’s a worthwhile investment. With some practice and patience, you’ll soon be on your way to capturing better, sharper, and more detailed astrophotography images.

How to Use an Autoguiding System

Once your autoguiding system is set up, it’s time to put it to use. Here’s a basic step-by-step guide to get you started.

The Calibration Process

Before you can start using your autoguiding system, it needs to be calibrated. This process involves the software learning how much it needs to adjust the mount’s movement to compensate for the guide star’s motion. Most autoguiding software will guide you through this process, which typically involves selecting a guide star and letting the software make some test adjustments.

Understanding and Adjusting Settings

Once your system is calibrated, you can start adjusting the settings. One of the most important settings is the ‘aggressiveness’ of the corrections. Setting the aggressiveness too high can lead to overcorrections and a ‘chasing’ effect, where the system is continually making large adjustments. On the other hand, setting it too low may not provide enough correction, leading to star trailing in your images.

Another crucial setting is the exposure time for the guide camera. Shorter exposures will provide more frequent updates, but the guide star may not appear in every frame. Longer exposures ensure the guide star is always detected, but you might have longer gaps between corrections.

Troubleshooting Common Issues

Like any complex system, autoguiding systems can encounter issues. Common problems include not being able to find a suitable guide star, the guide star disappearing during a session, or the corrections not having the desired effect. Each of these issues can usually be resolved by adjusting the settings or re-calibrating the system.

Understanding how to use your autoguiding system is an important step in improving your astrophotography. With practice and patience, you’ll soon be capturing breathtaking images of the cosmos.


What equipment do I need for autoguiding?

For autoguiding, you will need a guide scope, a guide camera, a computer with autoguiding software, and a motorized mount compatible with the software.

Do I need a special camera for autoguiding?

While you don’t necessarily need a “special” camera, a dedicated guide camera will typically provide the best results due to its high sensitivity and compatibility with autoguiding software.

How do I choose a guide star?

Most autoguiding software can automatically select a suitable guide star. It’s best to choose a star that’s near your target and bright enough for the guide camera to detect.


Autoguiding is a powerful tool in astrophotography that enables you to capture the breathtaking beauty of the cosmos in vivid detail. It may seem complex at first, but with some patience, practice, and the right equipment, it’s an accessible technique that can dramatically enhance your astrophotography skills. So, why not give autoguiding a shot and see how it transforms your celestial captures?