Shooting the Night Skies

As you may know, Night Photography is something that I really enjoy and whilst I do have the capability to shoot through a telescope for Astro shots, I know that many don’t – but with a basic DSLR, some standard kit lenses and a tripod you can easily start getting some shots of the night sky.

So - just how do you go about taking Astrophotography images with basic equipment?

My astro set-up

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The tripod is arguably the most important thing here – the camera will need to be held steady for a long enough period of time to capture the shot (at night there’s obviously a lot less light about which means using a longer shutter time to get enough light onto the sensor).

Using a tripod

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One of the biggest issues we all have taking photos of the night sky is light pollution which causes an orange tint to the shot – getting out of the towns/cities is a great help (getting to a dark sky site is even better), but it’s still possible to shoot through the light pollution and many places are replacing the older orange sodium streetlamps with new white LED ones which face downwards, helping to alleviate the orange glow that surrounds towns.

What settings to use?

For night photography it’s best to switch to full manual on your camera so you can adjust all the variables – shutter speed, aperture & ISO. In a nutshell, we’re looking to maximise the light hitting the camera sensor – so long shutter time, wide open aperture and high ISO – but there are some limitations which restrict just whacking them all up to max!

First of all, let’s look at the shutter speed – as we all know, the Earth spins so the stars cross the sky above us. If we’re looking to get stars as points of light, we must limit the time of the exposure in order to avoid star trails. Luckily there’s a simple formula to work out how long you can hold the shutter open for before trails start to form – generally called the 500 rule. If you divide 500 by the focal length of the lens you are using, the result is the number of seconds you can keep the shutter open for before trailing starts. For example, if you’re shooting with a 24mm lens, 500/24 = 21 seconds (rounded). Note that this is for a full frame camera – if using a crop sensor, divide again by the manufacturers crop factor (for Canon this is 1.6, so a 24mm lens on a crop frame Canon will be 500/24 = 21, 21/1.6 = 13 seconds). I always err on the side of caution and knock a couple of seconds off this just to be sure. Some of you may have heard of this in a similar vein as the 600 rule – but from experience, using 600 rather than 500 results in too long a time for the shutter to be open and when you zoom in on the resultant image, star trails can be seen.

Next, as we’re maximising the light reaching the sensor, we want to have the aperture wide open (which is as low an f number as possible). How wide open you can get will depend on the lens being used…if you’re using a telescopic lens it’s likely to vary from perhaps f5.6 upwards, prime lenses tend to be able to go much lower - such as f/1.8 or f/1.4. Key thing is not to go the opposite way and shoot with a very narrow aperture!

For ISO, this is going to be very dependent on the camera you have – the higher the ISO, the higher the noise (graininess) in the image. As an example, with the older Canon 1300d crop camera I have, I can push the ISO up to 800, even 1600 at a push; whereas with the newer Canon 6D MkII I can push the ISO up to 3200 easily and even beyond (light pollution comes in to play here too as the ISO, whilst amplifying the light from the stars, is also amplifying any ambient light). This best thing to do here is to experiment a bit by taking a few shots at differing ISO values and see how far you can push the ISO on your camera.

How to focus?

There are a couple of approaches to focusing – both result in switching to manual adjustments. One is to go with the fact that the stars are so distant that you can manually set the lens focus to infinity (the little icon that looks like a number 8 on its side). In practise I’ve found that the best setting is a little before the infinity stop – take a shot, zoom in on the image and check the star size. Make any adjustments and take another test shot, repeat until you have the stars as pinpoints. The other method is to start with the focus on auto, point the camera at the moon and let the auto focus adjust – once focused, set the lens to manual focus to stop any further adjustments once you re-direct the camera to the shot you’re after. If the moon isn’t out, a distant light source such as a street lamp will suffice.

So, now you’re armed with a basic understanding of night photography – time to get out there and take some shots!

One last tip for night photography – consider the composition of the shot. When taking wide field night shots it can be a good idea to have some foreground interest which helps gives the shot some grounding.

Thanks for taking the time to read this - hope you’ve gained something from it and are more confident in getting out there with your camera at night.

Click on the image below to see some more Astro/Night shots I've taken...

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