The star Antares shines high above the sand dunes on a winter’s night in the Iranian desert.
On the eastern horizon, the billions of stars in our home Galaxy glow patchily.
Capturing scenes like these using relatively basic equipment has become my main passion in astrophotography during the last 16 years.
These ‘landscape astrophotos’ provide a context many people can relate to: they define the night sky as an essential part of nature, not just an astronomer’s laboratory.
They also convey how viewing the heavens with nothing but the naked eye can be a sublime experience.
I have attempted imaging with a telescope and I appreciate the beauty and challenge of deep-sky astro imaging.
For this, sophisticated equipment is essential and considerable time is needed to process an image.
But for landscape astrophotography the reverse is true: processing is usually less involved and you need only the most basic gear, just a camera and a tripod.
Where to begin
The best place to start is by shooting scenes at twilight – perhaps the constellations.
It’s best to capture constellations using a wide-angle camera lens with an open aperture (around f/2.8) and an exposure of 10-30 seconds.
You’ll soon realise that longer exposures cause the stars to trail in your image because of the constant motion of the sky due to the Earth’s rotation.
An exposure of several minutes clearly shows these star-trails, which have their own beauty, but in order to ‘freeze’ stars as fixed points in your image (like below, in the panorama of the Milky Way above the Alborz Mountains), exposures should be short.
If you’re taking a picture of stars high up in the night sky – far from the celestial equator, either to the north or south – you can increase the exposure time.
Stars appear to move faster the closer they are to the horizon.
Mid-way between the celestial equator and the star Polaris, for instance, you can expose for 40 per cent longer.
And for the Big Dipper near the celestial pole, you can expose for up to 70 per cent longer.
Capturing star trails
Star trails make dramatic pictures.
An hour-long exposure on a fixed tripod creates beautiful trails.
Pointing the camera towards Polaris, for example, results in arcing trails around the celestial pole.
Remember that light pollution limits these long exposures, so star-trail images are best taken from a dark location.
Digital cameras also create ‘noisy’ images from these long exposures, but you can use a camera’s noise reduction option to eliminate this.
Or you can create star trail pictures by putting together a sequence of images with shorter exposures.
With a DSLR camera and a remote control, if you take 100 30-second exposures with only a second’s delay between each photo, you can then ‘stack’ the images together with easy-to-use freeware like Startrails.
This will reduce noise and the effects of light pollution.
Using a mount
You can stop stars trailing by placing your camera on a tracking mount. The Astrotrac mount sits on top of standard photographic tripods, and you can also try cheaper equatorial mounts.
With one of these, a high ISO setting on your camera, a wide-angle lens and a 1-2 minute exposure under a dark sky results in amazing starry views.
However, this has one drawbau ck: when you track the sky, the Earth will move in your image.
Freezing the foreground with a burst of flash is a good trick to overcome this.
Lighting the landscape
There’s no golden rule on how to illuminate the landscape in astrophotos.
Only with practice can you find the best balance of starlight and foreground illumination.
Too little light on foreground objects and stars float unanchored above a featureless silhouette.
Too much light might cause an object’s reflected glare to wash out the faint glimmer of stars above.
The source of illumination may come from twilight, the artificial lighting of a nearby town (such as Tehran in the picture below), or your own flashlight as you ‘paint’ the foreground.
A great source of light is the Moon – you’ll be amazed how a quarter Moon illuminates the landscape while the sky is still starry.
Planning your pictures
When you’re starting out, taking landscape images is fast and easy.
However, the secret of success is to be in the right place at the right time.
Planning is important, so use planetarium software like Stellarium and Sky at Night Magazine’s monthly Sky Guide.
Besides the weather, you’ll need to take into account such factors as geographic location, altitude and temperature, local topography and light pollution.
Any landmark on the planet with a starry sky above it will make a spectacular photo.
But you can also take impressive images from urban areas, especially during twilight.
For my photography, I’ve travelled to remote regions such as Antarctica, the Amazon and the Himalayas.
I’ve seen views that will stay with me forever – stars rising over Mount Everest, the Milky Way from the heart of the Sahara, and the dancing aurora above the fjords of Norway.
But my favourite place is only an hour’s drive from home in Tehran, at the foot of the legendary Mount Damavand, the highest mountain in the Middle East.
This splendid snow-covered volcano rises from the Alborz mountain range of Iran, and while the sky above the city is dominated by strong light pollution, just 65km away in the Alborz Mountains it’s still dark and starry.
This article appeared in issue 58 of Sky at Night Magazine, March 2010