How to take nightscapes

In the first part of our six part series on astrophotography, we show you how to capture great pictures with simple-to-use, inexpensive equipment. A camera and a tripod is all you need to start taking photos of fantastic ‘nightscapes’ – big, wide-field views of the heavens encompassing things like bright stars, the Moon, and the great sweep of our own Galaxy, the Milky Way.

A star trail image captured by Chap Him Wong that won the 'People and Space' category in the 2015 Astronomy Photographer of the Year competition. Credit: Chap Him Wong

There’s a huge range of subjects up there in the night sky just waiting to be captured with simple-to-use, inexpensive equipment.

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A camera and a tripod is all you need to start taking photos of fantastic ‘nightscapes’ – big, wide-field views of the heavens encompassing things like bright stars and the Moon, and perhaps set against a horizon.

These types of shots are particularly good when that great sweep of stars that makes up our own Galaxy, the Milky Way, takes centre stage.

Your pictures can also reveal the movement of the Earth by capturing star trails and tracking the changing positions of the planets over days, weeks and even months.

Closer to home there are meteor showers to watch out for, as well as ethereal noctilucent clouds and the shimmering greens and reds of the striking Aurora Borealis.

All this and more can be captured with the most basic of equipment: a camera, a tripod and a remote shutter release. Read on to find out how to do it.

EQUIPMENT

What you need to take your first quality astrophoto

Many of us have a compact camera we use to take everyday pictures, so why not turn it on the night sky?

Today’s compacts can take reasonable images in low-light conditions, and some even include manual modes that let you take full control of the camera’s functions.

The ability to adjust a camera’s settings for yourself will make for much improved images.

With the latest Canon PowerShot compact, you can keep the camera’s shutter open to the starlight for up to 15 seconds, and make its imaging chip very sensitive to light, with ISO values up to 3200.

The Nikon Coolpix P500 also allows for manual shooting at these high and sensitive ISO values.

Settings like ISO allow you to capture a wide array of subjects, but there is a downside to compact cameras.

Their lens sizes and zoom abilities often don’t let as much light reach the imaging chip as wider DSLR camera lenses do.

And being fixed, they don’t have the flexibility of a DSLR’s interchangeable lenses.

DSLR (Digital Single Lens Reflex) cameras offer a much wider range of functions and most experienced astrophotographers will have one in their arsenal.

They have the widest range of settings, providing full manual control.

They also have interchangeable lenses so you can swap to a more powerful lens to get close in on a bright star cluster like the Pleiades in Taurus, or a nebula like the Flame Nebula in Orion.

Many DSLRs also have an option to set the opening of the camera’s shutter – the exposure – in increments of seconds up to 30 seconds.

After that, they’ll have a bulb or ‘B’ setting for even longer exposures – great for capturing star trails.

In our reviews, Canon and Nikon DSLRs have stood out for what they offer budding astrophotographers.

The Canon 300D, 400D and 500D models are all good entry-level DSLRs for astrophotography, as is the Nikon D50 and D90. Fuji’s S3 Pro has also performed well in our tests.

TECHNIQUE

DSLR camera settings for astrophotography

Bulb The bulb setting allows you to precisely control the length of exposures.

With it you can take shots lasting from one second up to several minutes and even longer, using a remote shutter release or the delayed timer.

Such a wide range of exposures can be creatively exploited in your shots of the night sky.

Stars can be made to look like pinpricks with a short exposure or trails with a longer one.

File format

Many cameras come with a range of file format settings that include RAW, JPEG, RAW+JPEG and even the JPEG settings can have a wide choice of compression levels.

Get to know your camera’s file formats and ideally use the RAW setting.

While this will produce the highest quality results, it will also save the least number of images on your memory card because of the large file size.

Noise reduction

This is an in-built facility in many digital cameras and it should be used carefully.

When taking pictures with a lot of light across the image, for instance in twilight scenes, noise reduction can improve the shot by cutting out artefacts that are inherent in the camera’s sensor.

However, when used on pictures of stars and constellations, noise reduction can remove fainter stars. In these circumstances, it’s best turned off.

Picture styles

This is another in-built facility that has to be used with caution.

Many DSLRs allow you to alter settings like a picture’s contrast, sharpness and colour saturation and save the alterations as a user-defined setting.

Subtle adjustments made here can enhance the final image, but it’s very easy to alter a picture too much by going over the top.

The default settings are often the best to begin with.

MASTERCLASS

Capturing star trails reveals the dynamic night sky

In the northern hemisphere the stars appear to rotate anticlockwise around one particular star – Polaris, the Pole Star.

This star is almost exactly on the celestial pole.

It’s not quite, but is certainly close enough for all intents and purposes.

Over the course of 24 hours the stars complete a full circle around Polaris.

If you take a 10-minute, wide-field exposure that includes the Pole Star, you’ll see in the result that the stars further from Polaris have longer trails.

The arcs get longer as you move from the pole towards the celestial equator until, at the celestial equator, they are at their longest.

South of this the arcs begin to decrease in length again towards the south celestial pole, which for us here in the northern hemisphere lies below the horizon.

Star trail pictures in four steps

Equipment Select your lens and fix your camera to a tripod.

Adjust the tripod legs so that they provide a solid base.

Attach the remote shutter release so you don’t vibrate the camera when taking the shot.

Camera settings

Select the ISO, switch the camera to ‘bulb’ mode so there’s no limit to the length of the exposure, and focus.

Make sure your flash is disabled and switch on the long exposure noise reduction.

Subject

Decide whether to shoot short star trails near Polaris, or longer trails by aiming at a constellation near the celestial equator.

Ursa Minor is good for the former while Orion is good for the latter.

Capture and review

Take several exposures ranging from five minutes up to half an hour and review them on the preview screen.

If the sky is too bright, reduce the ISO and set the aperture to a larger f-number.

SOFTWARE

Take your shots from camera to the finished product

One of the best thing about digital images is that you can make them even better before you proudly show them off, by tweaking them with photo-editing software like Photoshop or with free software like GIMP.

With photo-editing software there’s so much that can be done that it can seem a little daunting at first, so we’ve singled out a few key adjustments to make, like adjusting the ‘levels’, the range of light and dark pixels in the image, to change the tone of the image and reduce the effects of light pollution.

Key image-editing adjustments

Histogram

The histogram tool allows you to adjust the contrast and brightness range of the pixels in your image.

It’s a very useful aid in making stars stand out and reduces the effects of light pollution.

By adjusting the histogram you can bring out detail that may be lost in the background.

Levels

Like the histogram tool, the levels tool can help reduce the effects of light pollution by giving you control over the amount of red, green and blue in an image.

Making subtle changes to the red, green and blue levels can dramatically reduce the orange hue created by light pollution.

Colour balance

This tool has three sliders, each controlling two colours: yellow and blue, magenta and green, and cyan and red.

By moving the sliders you can change the balance of colour between the two colours.

Watch the changes to decide how far to go with each slider for the best effect.

Sharpening and softening

One way to improve an image is to slightly soften or blur the pixels with the softening filter.

This reduces the effect of any noise in the image.

Use carefully, as it can soften the stars as well.

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The sharpening filter can also be used to make the image and stars look crisper.