Taking photographs of the night sky might seem like a mine-field but Astrophotography doesn’t have to be that hard. If you have an SLR camera, a tripod and a coat, this blog will have you started in no time. You’ll learn everything you need to know about taking photos of the stars and I’ll explain all the camera settings for stars that you’ll need.

Astrophotography – CAMERA SETTINGS FOR STARS

Taking photographs of anything in the night sky is astrophotography, not only stars and planets, but celestial events as well.

astrophotography
Astrophotography

“In the midst of darkness, light persists.”

Mahatma Gandhi

The first photograph of the moon was taken in 1840 and since then, taking long-exposure photographs of the sky at night has helped us understand what’s out there in space. Of course, most of it we can’t see with the naked eye. The camera will see things we can’t!

You can quite easily take crystal clear images of space, the stars, constellations and planets, shooting stars, satellites, maybe even the International Space Station, by applying the techniques in this blog.

Taking photographs of stars

When you’re taking photos of tiny white dots in the blanket of night, you need to let as much light in as possible.

To capture the light from distant stars, specs in the darkness you will need to open the aperture on your lens to it’s maximum (lowest number, e.g. 4.5). Sensitivity needs to be very high, I use 1600 or 3200 ISO for most shots.

That only leaves shutter speed.

As I said, you want as much light as possible hitting the sensor but not too long that you get star trails, movement in the stars. This is the only tricky bit so stick with me on this one. Once you’ve worked this bit out, you’re on your way.

To work out how long you can have the shutter open for, without getting star blur, you will need to apply the 500 rule.

Astrphotography by Lake Cwellyn
Astrphotography by Lake Cwellyn – 18mm f/3.5 20s ISO-1600

I took this photo by Llyn Cwellyn of a tarp I’ve developed for wild camping with the night sky as the back-drop. With the 18mm lens, I set the aperture to f/3.5 and ISO 1600. A 20 seconds shutter speed gave me the perfect exposure, although you can see the star near the top of the frame is slightly blurred.

The 500 Rule

Earth spins on its axis. We are passengers, like on a merry-go-round. Every now and again (and again, and again) we see stationary objects, and they see to be moving. Stars look like they are drifting through the night sky. If we take a picture of something that is ‘moving’, open the shutter on the camera for long enough, we’ll see blur. When you do this with stars, the little blurs are called star trails.

In astrophotography, so that we don’t get star trails in our photos, we need to work out the maximum time that we can have the shutter open. We use the 500 rule for this, some call it the rule of 500.

Using the 500 rule

The basic 500 rule works for a full-frame camera. You divide 500 by the focal length of the lens you are using. If you were using a lens with an 18mm focal length, the rule of 500 would suggest that I open the shutter for no longer than 28 seconds (500/18).

Having two Nikon crop sensor cameras, I need to amend the basic rule. The crop factor for my Nikon D5300 is 1.5. My 18-55 mm kit lens, fully zoomed out has a focal length of 18 mm (the numbers on the lens are a giveaway). Putting that into the 500 rule, using the 18mm lens, I get 500/18/1.5 = 18 seconds.

If you don’t know your cameras crop factor, click here and add your camera’s name to the search – Google.

Replace the 1.5 in my equation with your crop factor. This table gives you an idea of the range that there is between different camera and lenses.

Lens Focal LengthFull Frame Camera1.5 Crop (Nikon)1.6 Crop (Canon)
14 mm36 sec24 sec22 sec
16 mm31 sec21 sec20 sec
20 mm25 sec17 sec16 sec
24 mm21 sec14 sec13 sec
35 mm14 sec10 sec9 sec
50 mm10 sec7 sec6 sec
70 mm7 sec5 sec4 sec
85 mm6 sec4 sec4 sec
135 mm4 sec2 sec2 sec
200 mm3 sec2 sec2 sec
Table showing maximum shutter speeds for a range of camera/lens setups

Camera settings for stars

This isn’t rocket science so let’s get the camera sorted out, get outside and take some photos.

Nikon D5300 digital SLR camera
Nikon D5300 digital SLR camera

Set your camera to Manual mode by moving that dial to M.

Scary? With astrophotography, this is where the magic happens.

Aperture

Start by setting the aperture opening to it’s maximum, letting as much light in as it will. For the maximum opening, the corresponding aperture number is low – 1/5.6 is bigger than 1/29 for example.

ISO

This should be set quite high, very sensitive to light, at about 1600 ISO. You can play with this in time but this is a good starting point that you don’t need to change for now.

Shutter Speed

The shutter speed, or the time you have the shutter open, is the only setting that you’re going to change now. Using the 500 rule above, you’ve worked out the maximum time you can have your shutter open before you get star trail blur. So, let’s start with that. On my Nikon D5300, I’m going to start with 18 seconds.

Shutter speed settings

My settings actually only give me options of 15 or 20 seconds, so I’m going to start with 15. At least this way, I know that if there’s blur it’s not down to the shutter speed. Once I’m getting a good image, I can try 20 seconds if I need more light.

Photographing the stars at Llyn Cwellyn
Photographing the stars at Llyn Cwellyn – 18mm f/3.5 20s ISO-2000

See, in the photograph above, how the light pollution from Caernarfon destroys the Milky Way. Astrophotography and streetlights are not friends. I was happy enough with the photo at the time but to really get the detail you need dark skies.

Focussing on the stars

OK, there is one other fiddly bit. Focussing on the stars is tricky, but if you follow this method, you’ll be fine.

I’ll zoom my lens right out to 18 mm and set my aperture to it’s maximum, 3.5. Then, I’ll point the camera so that the brightest thing in the sky, like a star or planet, is in the centre of the lens. Focus as best you can on that. If you have a live view option on your camera, and a back screen, you can move the focus ring back and forth to improve the focus.

Carson Lumiloupe 10x

Carson Lumiloupe 10x

To get the focus even more accurate, you can place a magnifier loupe on the screen. This is the same thing that jewellers use to look at jewellery. You can pick a Carson Lumiloupe up for £7 on Amazon here.

Don’t move the focus ring. To eliminate any movement on the focus ring, I’ll put electrical tape around it. This tape doesn’t leave a sticky mess behind.

Wild camping astrophotography by Llyn Cwellyn
Wild camping astrophotography by Llyn Cwellyn – 18mm f/3.5 20s ISO-1600

Condensation

The photograph above was taken at Llyn Cwellyn again, in January 2018. The temperature dropped dramatically after pitching, down to -1c before I eventually went to sleep under the tarp. With the camera being warm, moisture in the air condensates on the lens. Although this is not desired, I quite liked the image I got, dreamy, so I stuck with it.

Camera settings for stars

With all that out of the way, and hoping you’re still with us, we’ll get out and actually take some pictures shall we?

  • Get your tripod and camera set up.
  • Set your aperture to the max, that’s f/3.5 for me.
  • Your ISO should be 1600.
  • Set your shutter speed to what you worked out using the 500 rule, this is 15 seconds for me.
  • Point to the sky and get focussed if you haven’t already.
  • Now frame what you’re going to shoot and take the photo.
Great Bourne wild camp and Orion
Great Bourne wild camp and Orion

I love the Orion constellation so when I planned this wild camp on Great Bourne in the Lake District, I consulted the Star Walk 2 app to see exactly what time it would be behind the trig pillar. I pitched the Hilleberg Akto just to the left and set my alarm before I had a few hours shut-eye.

Handy app for astrophotography

My Nikon D5300 gives me a connection to my phone and using the Nikon app I can see the photo straight away on-screen. I’ll often use this to check that I’ve framed the image I want properly. This is not necessary but it is handy to see how the images look on screen. You can zoom in easier and check that everything looks good, like focus and exposure.

I hope this blog has given you some handy tips and shown you that astrophotography isn’t as difficult as you thought. I’d love to see some of your photos if this blog has helped you take better photographs of the night sky.

Wishing you clear skies, happy shooting.

Coming soon…

Shooting the stars with a GoPro. The Hero8 Black is now only £279 and you’ll be surprised what you can do with one!


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