Most people reel at the end of the daylight-saving period, as the clocks go back and the nights seem to suddenly draw in. It hardly even seems worth the extra hour in bed when the workday ends in darkness for the rest of the year. But for stargazers, the change represents opportunity. The earlier sunsets call to us, inviting us to seize the night and reacquaint ourselves with the unique splendour of the winter night sky. It’s also a perfect time for astrophotographers – both seasoned and new to the hobby – to dust off their lenses and make a plan for the long, dark nights head. If you’re eager to make a start at capturing the stars, why not set your sights on the mighty constellation Orion and hone your camera skills?
Orion’s central stars are easy to identify. To the upper left is the red-orange Betelgeuse. To the lower right is blue-white Rigel. Orion’s belt and beneath if, the sword, are at the heart of the constellation.
As we move through November and into December, Orion stands higher in the southeast around midnight. His famous belt, a trio of stars called Alnitak, Alnilam and Mintaka, guide us up to the Pleiades on the right, and down to Sirius – the brightest star in the night sky – on the left. But Orion is more than a signpost. It’s a richly populated constellation of colourful stars and delicate nebulae, which collectively comprise a grand structure in the Galaxy known as the Orion Molecular Cloud Complex.
The brightest stars of Orion are conspicuous to the eye, but cameras can go well beyond our visual sensitivity limits by using long exposures to integrate light and reveal faint details. To get the best results, there are several things to keep in mind when setting up and shooting. Here are my top tips for perfect results.
- Hands off!
Long exposures are fantastic for photographing the cosmos, but they aren’t suitable for handheld shooting. We want to aim for exposure times approaching or exceeding 30 seconds, so it’ll be necessary to take the shot without touching or moving the camera. A tripod is ideal, but even resting your camera on a table or chair with something to prop it upwards towards the sky is a fine way to start. Most modern cameras feature countdown timers of 2-10 seconds, so you can press the shutter and move away from the camera before the shot is taken. You could also investigate a third-party remote shutter, which is very inexpensive, or an app from your camera’s manufacturer for smartphone control.
- Stay focussed
Modern camera lenses have sophisticated autofocus systems that are perfectly tuned to quickly lock on to a subject. Unfortunately, they don’t work well for astrophotography at all, because the stars are typically too faint for be identified by the autofocus system. You’ll need to manually focus your lens, but luckily the focus ring will have an infinity setting. Start here and make very minor adjustments if necessary to achieve perfect focus. Use your camera’s live viewing function and zoom in on a bright star, such as Betelgeuse or Rigel, then adjust the focus ring until the star appears as small and sharp as possible. You might want to use a small piece of tape to hold the focus ring if you’re out on a cold night – sometimes the cooling of the lens causes its internal components to expand, nudging it slightly out of focus over time.
- Know your settings
When shooting a very low light scene like the night sky, it’s important to take pictures in a raw format, rather than a compressed format like jpeg. The raw format preserves many more shades and colours of light not visible on your camera’s screen, enabling a much greater latitude for processing your images afterwards. White balance isn’t important, as raw images can be adjusted after the fact, but take some time to experiment with the ISO setting and exposure time. To begin with, you’ll want to make sure your lens aperture is wide open (i.e. the f-stop is set to the lowest number) and your ISO is not cranked all the way. Try an ISO of 800-1600 with exposure times of around 10-30 seconds. Longer exposures will lead to star trailing as the Earth rotates, particularly if you use a longer lens, but shorter high-ISO exposures will have increased noise. It’s all about finding a balance.
Orion makes a fantastic subject even at shorter exposures. You’ll find that from a sufficiently dark sky site, your photos show nebulous detail around the belt and beneath it. The belt and sword are a particularly interesting region to zoom in on with longer lenses, such as telephoto lenses. Capturing details here without some kind of tracking system is difficult, but by keeping your exposures short its possible to reveal details in the glorious Great Nebula in Orion – sometimes known as M42.
The Great Nebula in Orion (M42) glows with the light of thousands of young stars. It is a star nursery over 1,000 light-years away, presenting a mixture of colours not visible to the eye. The left-most star of Orion’s Belt, Alnitak, is close to the Flame Nebula and Horsehead Nebula.
Orion’s Belt is also adjacent to some famous, albeit fainter nebulae. The Flame Nebula and Horsehead Nebula lie close to the star Alnitak. This scene, sometimes known as the Jewels of Orion, is rewarding to capture when you start your astrophotography journey. You’ll probably be surprised by just how much is visible in your photos. Looking even deeper, a very long lens or telescope can be used to zoom in on M42 and its associated nebulae. M42 is a popular ‘deep sky object’ for astrophotographers using dedicated imaging cameras and telescopes, but you’ll need to track the sky and take a sequence of images to achieve the best results. By combing long exposures, astrophotographers can greatly reduce the noise or grain in the final image and bring out additional details including richer colours. This process is known as ‘stacking’.
High quality telephoto lenses and compact telescopes are well suited to framing this beautiful vista along Orion’s sword. Delicate details in the Great Nebula are visible, including the ‘fish head’ – a dark protrusion seen in silhouette against the bright cavity of glowing gas. To the left is the fainter Running Man Nebula. Consider this an additional challenge as you develop your astrophotography experience.
Even with relatively modest equipment, it’s possible to achieve richly detailed portraits of Orion, with many of its subtle features made visible. You’ll just need to jump into stacking and processing your images. Some astrophotographers say that postprocessing is nine tenths of astrophotography, and while that’s probably a little exaggerated, it’s certainly true that you can spend a lot of time improving the result with software. For this reason, be sure to keep your raw image files safe and return to them as you become more familiar with the tools and techniques that result in the most beautiful images. You’ll find you can breathe new life into your old image data – a perfect project for a cloudy night!
This deep field image makes Orion almost unrecognisable, as its brightest stars melt away into an ocean of background starlight. With just a modest camera and 50mm lens, combined exposures can draw out significant regions of the Orion Molecular Cloud Complex.
Astronomy Photographer of the Year: Collection 11 is the perfect gift for astrophotography enthusiasts. Be captivated by 140 winning and shortlisted images from the 2022 Astronomy Photographer of the Year competition, hosted by Royal Observatory Greenwich.
About the author
Tom Kerss is an astronomer, astrophotographer, writer and speaker, specialising in the rewarding task of connecting people to their shared universe. He is the author of Northern Lights, Moongazing, Stargazing and You Can Explore the Universe, all of which are available now.
His new book, Observing Our Solar System, is out now.