I love capturing beautiful nightscape photography, and I’m always happy to share what I know and what I learn. I’m keen to inspire others to head outside and look up at the sky, and to photograph the sky.
So I’ve started a series of posts with the theme ‘Nightscape Photography 101‘ – sharing tips and tricks to help you take better nightscape photos.
In this second blog post, I’m going to discuss the Fundamentals of Nightscape Photography – the basics of capturing enough light at night-time, an introduction to celestial mechanics (how the sky moves at night), my 5-point plan to capturing a nightscape, and whether a cookbook recipe can actually work for nightscapes.
The Earth Turns
The Earth rotates on its axis once every 24 hours. The symptoms of that, is that objects in space appear to move across the sky – rising in the East and setting in the West.
Standing outside at night looking up at the sky, you may not always notice it – but if you take note of the position of some bright stars relative to something, like a mountain, tree, roof of a house etc, and then check again an hour later, you’ll see that those stars have moved a fair distance (15° to be exact).
The Celestial Sphere
Imagine that the stars are projected onto a ‘sphere’ up in the sky, with the sphere rotating around two points in the sky we call the ‘South Celestial Pole’ (SCP) and the North Celestial Pole (NCP).
If you live in the Southern Hemisphere, look towards the south, and the point in the sky directly above the South Pole is called the ‘South Celestial Pole’. If you live at 33deg S latitude, then the SCP is 33deg above your horizon. If you live in the Northern Hemisphere, the point in the sky directly above the North Pole is called the ‘North Celestial Pole’. The star ‘Polaris’ is very close to your NCP. The altitude of Polaris will be the same as your latitude (eg: 30deg N).
Stars closer to the celestial poles travel in arcs and appear to move slower, whereas stars towards the East or West appear to move faster.
In the image above, the stars are rotating around the South Celestial Pole, which is 33deg above my horizon. The further out from the SCP or NCP you go, the stars travel in longer arcs as they have more ‘distance to cover’ to circle the Earth once every 24 hours.
If you face directly East or West, the stars will be ‘straight’, but not necessarily 90deg perpendicular to the horizon. The angle at which the stars rise depends on your latitude again. If you’re at 33deg latitude (north or south), then the stars will rise at an angle of 57 deg (90-33). If you lived on the Equator, the stars would rise and set perpendicular to the horizon.
In the image above, I was at Cable Beach, Broome, which is at about 18° S latitude. You can see in this wide angle image, exposed for 15 minutes to create star trails, that the stars directly to the West (in the middle of the frame) are at an angle of approx 72°. The stars on the left are arcing towards the South Celestial Pole (18° above the horizon), and the stars on the right are arcing towards the North Celestial Pole (below my horizon).
So what’s it all mean?
It’s this movement of the Earth, the movement of the sky, combined with the lack of light (it’s night time!), that makes nightscape photography challenging but opens up creative opportunities at the same time. You get to decide – do you want the stars as points of light, do you want star trails?
In the next section, we’ll discuss how to expose for just long enough so that you do not see the rotation of the Earth in your shots – so you can get stars as points of light and not streaks.
If you’re just starting out in nightscape photography, some of this Celestial Mechanics section may have gone over your head – you may not use this information immediately, but as you become more advanced you’ll definitely need to know this stuff. You’ll need to know when the Milky Way will rise, how long it takes to cross the sky, why are you getting star trails in your photo, what to do when you want star trails etc.
Plus, it’s exciting just to know this stuff – to be able to stand outside and look up at the sky and know what’s happening and why. The more you learn about astronomy, the more you’ll just love standing out under the night sky and capturing its beauty. I’d suggest embarking upon some more of your own reading about it, here’s a few articles to get you going: How the sky works, Beginners guide to the night sky.
It’s Dark at Night
Photography is about capturing light, right? So what do you do when it’s dark and there is no light?
That’s the challenge of nightscape photography – pushing your camera and lens to the limit to capture the scene and still have it sharp and well exposed while satisfying your creative juices of what you had in your minds eye!
Our eyes are terrible in the dark. When you’ve allowed them to become dark adapted they’re much better at seeing stars and the Milky Way and foreground scenes at night, but they’re just not as sensitive as modern cameras. The benefit the camera has, is that it can ‘expose for longer’ – capturing more light to build up the scene.
Unfortunately we can’t change the shutter speed of our eyes 🙁 So we want to capture more light at night. We can simply keep the shutter speed open for a few minutes, right? Unfortunately not – remember your primer on Celestial Mechanics above? During that time, the Earth is turning and the stars will turn into trails.
The number one rule, the key to nightscape photography, is capturing enough light in the shortest amount of time possible. That’s it! Everything else is either a trade-off, or a creative choice.
How do we do that? There’s 3 factors you can control about how much light comes into the camera, the ‘exposure‘ – Shutter Speed, Focal Ratio and ISO. They can work together, or work separately but will ultimately depend on your creative choice (the scene you’re trying to capture), the amount of light available, and the limitations of your camera and lenses. I’ll explain each below.
Let’s assume that you want your stars to be points and not trails. The first thing to work out is how long you can keep the shutter open for, before you start getting star trails. This depends on the focal length of your lens, and whether your camera sensor is full-frame or a ‘crop sensor’. The longer your focal length, the sooner your starts will turn into trails. The wider the field of view (the shorter the focal length), the longer you can go before you get star trails.
You may have heard of the ‘500 rule’ or ‘600 rule’. It’s a formula that can help you work out how long you can expose for before getting star trails, given the focal length of your lens. The formula states:
600 / focal length of your lens = exposure time (shutter speed).
Or, more specifically and covering both the 500 and 600 rule, for both full frame and crop sensors for a variety of focal lengths, use this table to help you calculate the maximum shutter speed you can use before you’ll start getting noticeable star trails in your nightscape photos.
Download PDF to print out and keep in your camera bag!
Use the 600 rule for longer exposures and web images where slight trailing won’t be noticeable, or use the 500 rule if you’re more conservative or plan to print your images at 30” or higher. For custom focal lengths, simply divide 500 or 600 by the focal length of your lens. Example, for a 20mm lens: 600 / 20 = 30 seconds on full frame, or 600 / (20*1.6) = 19 seconds on a Canon crop camera or 600 / (20*1.5) = 20 seconds on a Nikon/Sony crop camera.
So that’s the first step done – set the shutter speed of the camera to the maximum you can go before you get star trails, with your given camera and lens combo.
The focal ratio is the depth of field, and is controlled by the aperture of your lens. The aperture controls how much light comes into your lens and hits the camera sensor. The minimum focal ratio you can set is a function on the lens – and some lenses only go to f/3.5 or f/4.0 when wide open (smaller number, we call that a ‘slower lens’), while more specialist or more expensive lenses can go down to f/2.8 or f/1.8 (we call that a ‘faster lens’).
Depth of field/focal ratio is usually a creative choice – depending on what we’re photographing, we might want the whole scene in focus (large depth of field), or a foreground subject or person in focus while the background is out of focus (shallow depth of field).
For night photography, throw all of that out the window. Remember rule #1 above? We want the maximum light possible in the shortest amount of time – so we want to use a wide open aperture. As you can see from the image below captured on Piccanniny Creek bed, the whole image can still be in focus with a wide-open aperture.
Landscape photographers are always horrified by this – they almost never use the lens wide open. When you’re shooting landscapes you want a greater depth of field – you want the whole scene sharp, and most lenses don’t perform as well wide open – their ‘sweet spot’ is usually around f/8 – f/11. So why would you want to shoot wide open? Like I said, Light! Shooting wide open gives you that light. We sacrifice a little quality of sharpness, especially around the edges and corners of the frame, to be able to keep the exposure time as short as possible.
There are some lenses, when used wide open, that the aberrations in the corners are so bad that we do intentionally stop the lens down 1 or 2 stops (from f/1.4 or f/1.8 to f/2.8 for example), but I consider f/2.8 the minimum you need. Any slower than that (eg: f/3.5, f/4) and you’re not getting enough light in for the exposures to remain under 30 seconds and freeze the stars as points.
As you can see in the image above, corner performance is terrible with the Canon 50mm lens @ f/2.0, however the middle is very good. You’d need to crop the image or stop the lens down to a slower speed (f/2.8 for example).
What if you only have lenses that go to f/3.5 or f/4.0? You can still use them, but unfortunately you’re going to be limited in what you can do and the creative choices you can make. You’re likely going to need longer exposures to get enough light in for a well-exposed shot, resulting in streaks for your stars instead of points of light. Long star trails are perfect for slower lenses.
Ultimately, as your experience and passion for nightscape photography increases, like the rest of us, you’ll probably end up buying faster lenses (f/2.8 or faster) that give you more creative choice of the scenes you’re able to capture.
ISO is like digital amplification – the higher the ISO, the more your signal is amplified, to artificially boost the sensitivity of your camera and the amount of light coming in.
So remembering rule #1 above, then you’ll set your ISO as high as it can go, right? Yes. Well, sort of. There’s always a trade-off. Higher ISO ‘boosts’ the signal to give you more light in a shorter amount of time, but at the trade-off of increased noise.
Landscape and portrait photographers generally use a low ISO – 100, 200, 400 at most, and only increase it when light-levels are low. They don’t want the graininess and noise that high ISO can introduce into your shot.
However at night, light levels are extremely low and we need a very high ISO to capture enough light. We accept the increased noise in order to keep exposure times under 30 seconds (for example).
So how high should you go?
The easy answer is, as high as your camera can go while still giving you a pleasing shot – or put another way, as low as you can go while still capturing enough light for a well-exposed scene. That’s going to be different for every camera and every person, but as a general guide, most DSLR’s will easily do ISO1600 with acceptable noise levels. Any higher than that with some cameras and you’ll get colour blotchiness, amp glow, hot pixels and lots of grain.
However, technology improvements in more modern DSLR’s have dramatically decreased the noise levels at high ISO’s – and it’s now extremely common to capture images using ISO3200 and even ISO6400 or ISO12800 with some cameras. With my Canon 5D Mk2, I use ISO3200 but with my Canon 6D I use ISO6400 and the noise levels are low and more than acceptable. See the image below for a great example of that.
It’s also worth pointing out that while there’s certainly graininess introduced at high ISO’s like 1600, 3200 and 6400, there’s great plugins and noise reduction programs that reduce and clean-up the noise in post-processing. See below.
The best bet is to experiment with your camera. Take several shots, using the same shutter speed (30s for example), same focal ratio (f/2.8 of f/3.5 for example) and different ISO’s – from 400, 800, 1600, 3200 etc and see the difference it makes to your photo – both in the amount of light captured and the amount of noise/grain introduced.
I’ll be writing an article in future to show the types of noise and different noise reduction techniques you can use to deal with them.
You now know the 3 factors you have control over in order to capture a nightscape photo. The combination of shutter speed, focal ratio and ISO (the ‘exposure triangle’) allow you creative choice but there’s always a trade-off.
You want the most light in the shortest amount of time possible, while accepting a loss of sharpness in the corners or edges (as a result of using the lens wide open), and more grain in your photos (as a result of High ISO).
But wait – you want a formula? An ‘ideal’ combination of settings to get you started? Keep reading.. 🙂
Mike’s 5 Point Plan for Capturing a Nightscape Photo
Everything I’ve explained above is to help you understand why we use the settings we do. But some people still just want a recipe – a set of steps to capture their first nightscape photo. I can help you with that.
Here’s my 5 point plan for capturing a nightscape photo – the same settings and steps I use on the majority of my ‘night sky’ nightscape photos.
- Face your camera towards a nice part of the sky. Facing east after 9pm from March to June is good as you have the Milky Way rising. More on composition and how to find something to photograph in the sky will be covered in a future post.
- Focus on infinity. That’s not always easy to do – pre-focus using auto-focus on something very far away before it gets dark, and then lock to manual focus. More on how to focus at night in a future post.
- Use the widest lens you have (under 20mm), on its fastest aperture (lowest number, eg: f/2.8, f/3.5)
- Set your camera to the highest ISO you can use (eg: ISO1600 or ISO3200 depending on your camera)
- Set the exposure to 30 seconds.
Press the shutter! Voila!
The result you get may or may not exceed your expectations – a lot will depend on the camera and lens you use, where you live, the light pollution, how dark the sky is, etc. But they’re the basic settings I use on most of the nightscapes I take and it’s a good starting point to work from.
Is that all there is to it? Yes.. well, sort of 🙂 There’s still a difference between good and great.. what makes a good nightscape photo? What makes a good nightscape photographer? Those are two topics I’ll cover in a future post.
Cookbook Recipe for Every Situation?
Is the recipe above all you really need to know? Of course not – there’ll always be situations and scenes that need different settings and there’s no one set of rules that will apply.
Here’s a few examples of when those settings won’t work:
- If the sky is brighter, for example if it’s closer to sunrise/sunset or twilight.
- If there’s more light pollution, closer to city lights
- If there’s a bright Moon in the sky
- If you’re shooting twilight conjunctions
- If you’re shooting towards the Moon
- As part of your creative choice, or given a particular foreground scene, you want to use a longer focal-length lens
- As part of your creative choice, you want to do star trails or are using the lens stopped down to a slower aperture.
However it’s a starting point, and you’ll be able to adjust from there.
In the shot above (Canon 350D and Sigma 17-70mm lens, f/7.1, ISO100, 1.6s exposure), while still technically a nightscape, you obviously wouldn’t use the ‘recipe’ – there’s situations where you’ll need different settings.
Now I hope you can see why I took the time in the first part of this post to explain why – so you can understand why the settings are chosen the way they are and over the course of this series you’ll learn enough to begin to understand which settings apply in which circumstances, and how to adapt them – to make your own adjustments to match the scene you’re presented on a given night.
My aim is to give you the knowledge and tools so you can understand what factors you can control and what levers you can play with to achieve the desired result.
I hope that explains and helps you understand the Fundamentals of Nightscape Photography. In the coming posts, we’ll talk about everything you ever wanted to know about nightscapes, including:
- capture techniques for the different types of nightscapes
- processing tips and tricks
- focusing at night
- my thoughts about what makes a good nightscape photo,
- my thoughts about what makes a good nightscape photographer
and much more.
Please feel free to ask questions in the comments section below. Let me know your challenges and frustrations and questions about nightscape photography, and I’ll add them to the list of topics I’ll cover!
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