Noise, noise, noise…
Too Close for Comfort (taken at 8000 ISO)
Noise is the bane of many wildlife photographers. It can easily ruin images shot in low light, and there’s no easy way to fix it. However, photography is all about trade-offs, and there are a number of things you can do in terms of your choice of equipment, your settings and your editing workflow that should allow you to create clean, high-quality images whatever the conditions.
What is Noise?
Noise is unwanted blotchiness in digital photographs—the equivalent of ‘grain’ in film cameras. It tends to be most visible in smooth, shadowy areas in the background, especially at high ISOs, and it can get worse if the camera overheats or if you’re taking a very long exposure.
If you use Lightroom, you’ll see tools to reduce two types of noise:
Luminance (or brightness) noise is a variation in tone, with some photosites on the sensor receiving more or less light than they’re supposed to, leading to brighter or darker pixels.
Colour noise is a variation in colour, with odd pixels being the ‘wrong’ colour.
However, there’s another way of looking at it:
Photon or shot noise is produced by the random variation in the number of photos hitting a photosite on the sensor.
Read noise is produced by voltage fluctuations and bit errors during image processing.
Noise is caused by a poor Signal-to-Noise Ratio (or SNR). The light the camera needs to take a picture is the signal. The noise is the background noise, variability and errors you get with all kinds of electronic equipment, whether for audio or video capture.
(And, yes, I know it’s confusing that ‘noise’ is used in two different senses!)
If there’s a lot of light, the SNR is high, so any interference is ‘drowned’ by the light coming through the lens, and your image quality will be high. In low light, the SNR is low, so you’ll get noisy images.
Images taken at high ISOs, such as 6400 and above, tend to look quite noisy, so it’s easy to assume that the high ISO somehow ‘causes’ the noise, but that’s not true. In fact, it just reveals it, dialling up the brightness as you would on your TV.
ISO measures the sensitivity of film, but in digital photography, it’s a measure of the artificial signal amplification being applied.
If you take two pictures at different ISOs, one correctly exposed at a high ISO and the other underexposed at a lower ISO but brightened in post, the first picture will have less noise—even though it’s shot at a higher ISO!
The reason you shouldn’t just whack up your ISO to the highest possible value is that you’d just be underexposing your images massively by narrowing the aperture and using a higher shutter speed and then trying to compensate by turning up the brightness. And, as you’ve just seen, you get more noise if you do that, not less.
All other things being equal, you should aim for a lower ISO to improve your image quality by increasing the light coming into the camera. There are only three ways to do that:
Widen your aperture.
Slow down your shutter speed.
Add artificial light, eg flash.
Let’s look at a few ways to reduce noise at three points: when you’re in the shop buying your gear, when you’re taking pictures in camera and when you’re editing them in post.
In the Shop
Dos
Buy a camera with a larger sensor
My full-frame Sony ⍺1
Noise levels are roughly proportional to the size of the sensor. This is because it depends on the total amount of light being captured rather than the light intensity—or the amount of light per pixel. That means a full-frame camera produces less noise than an APS-C camera, which produces less noise than a Micro Four Thirds camera and so on.
You can see this by looking at the ISOs needed in different cameras to achieve the same noise level. For example, a full-frame sensor is roughly four times the area of a Micro Four Thirds sensor, so a picture taken with a full-frame camera at 400 ISO will show the same amount of noise as a picture taken with a Micro Four Thirds camera at 100 ISO.
Buy a camera with a greater pixel pitch
The amount of noise increases with pixel pitch, which is simply the size of the photosites on a digital camera sensor. This is not as important as sensor size, but it’s still worth bearing in mind.
Full-frame or APS-C cameras with higher resolution sensors can produce images with greater detail, but they lose out in terms of low-light performance due to their smaller photosites, which can’t gather as much light.
Buy a camera with high resolution
Smaller pixel pitch increases noise, but higher resolution actually reduces it because the noise itself is finer and therefore more easily removed.
Unfortunately, the only way to get higher resolution without compromising on the pixel pitch is to get a camera with a larger sensor, and I don’t think many people will want to choose between full-frame and medium-format cameras!
Buy fast lenses
Most wildlife photographers shoot wide open most of the time, and they spend thousands on ‘fast’ prime lenses with wide maximum apertures of f/4 or even f/2.8. The benefit is that for every extra stop of light you let in through the lens, you save a stop of ISO. That means your images will be much less noisy.
Buy constant-aperture lenses
Zoom lenses often have variable apertures. That means the maximum aperture gets smaller and smaller as the focal length increases. As people tend to take more pictures at the long end of the zoom range, this is an obvious drawback in low light.
Don’ts
Don’t buy an old camera
One of the biggest predictors of noise is the age of your camera. Technology has advanced so rapidly that most cameras offer far better noise performance than they did even five or 10 years ago.
In Camera
Dos
Shoot in Raw
Raw formats collect far more data than JPEGs, which are compressed by default. You can choose compressed Raw formats, but you don’t have to, and the noise performance is generally much better.
In addition, there are other benefits, such as being able to change your white balance as many times as you like without affecting image quality.
Turn on your zebras
Mirrorless cameras often have zebra stripes that warn you when you’re likely to overexpose the image. Electronic viewfinders are What-You-See-Is-What-You-Get (or WYSIWYG), so it takes away a lot of the guesswork. However, zebra stripes are the icing on the cake.
Zebra stripes assume the camera is shooting in JPEG format, so you can actually push the exposure a bit higher if you’re shooting in Raw. I’ve set mine to 109%, which is a good starting point.
Take slow pans
Hot to Trot (taken at 1/50 of a second)
If you’re shooting action in low light, a good way to avoid noise is to take slow pans. The idea is to use a slow shutter speed to add blur to the background and the legs or wings of your subject while keeping the head sharp.
You can read all about it here, but one of the big benefits is that you can afford to use a much slower shutter speed than usual, which means more light gets into the camera and less noise is produced.
Fill the frame
Little Brown Job
If you fill the frame with your subject or choose compositions that focus on the surroundings, such as environmental portraits, you’ll have less need to crop your images. That means you won’t have to magnify the noise!
Create white or black backgrounds
Mug Shots (with the grassy background overexposed to turn it white)
If you want to increase your exposure but are worried about clipping your highlights, one option is to blow out the background and create a high-key image with a pure white sky. That way, you won’t care about any loss of detail as it’s now part of your artistic approach.
You can do the same with black backgrounds. Dark areas don’t show noise as much, and you can use a much lower ISO if you deliberately opt for a low-key image.
Use the Rule of Doubles
As Tony Northrup and others have pointed out, one way to push your shutter speed as low as it’ll go is to use the Rule of Doubles. The idea is simply to take more and more frames at slower and slower shutter speeds so that you maximise your chances of getting a sharp one.
Take a short burst at your ‘normal’ shutter speed for the shot—even if that pushes up the ISO a lot.
Halve your shutter speed and take a burst of roughly twice the length.
Repeat Step 2 until your subject disappears—or you get bored!
Review your images in reverse chronological order. The first sharp image you find will be the one with the lowest ISO—and therefore the lowest noise.
Don’ts
Don’t underexpose deliberately and brighten in post
Unless you happen to own an ISO-invariant camera, such as my Sony ⍺1, the Nikon Z9 or the Canon EOS R5, underexposing an image and then brightening it later will produce more noise, not less. This is important because it affects your workflow in the field.
Wildlife photographers love to shoot in low light at sunrise and sunset, and my default approach was to underexpose by a stop to add saturation to the colours. However, I’ve stopped doing that now because it just made my images too noisy.
By exposing correctly, I don’t end up halving the amount of light entering the camera, which means the background areas that are usually the most noisy are brighter than they would be. That reduces noise, and I can still produce underexposed images by darkening them in post.
Don’t overexpose deliberately and darken in post
Exposing To The Right (or ETTR) is a common technique to reduce noise. The idea is to expose the sensor to as much light as possible (without losing all detail by clipping the whites) and then darken the images in post.
A slight variation is to use 1/3 or 2/3 of a stop of exposure compensation by default. This is obviously easier and more convenient, but it’s not as accurate.
These approaches can work, but the danger of both is that you’ll accidentally clip the whites. This can easily happen if an animal has a white patch of fur on its body or if you take pictures of a white bird. If that happens, it’s impossible to recover any detail from blown highlights, so the image is as good as useless.
The other problem is that you have to monitor the histogram on your camera carefully, and I prefer to show the electronic level instead.
For these reasons, it’s not something I do myself, and it’s not something I recommend.
Don’t use the 1/focal length rule of thumb
Pig-aboo (taken at 1/125 of a second despite using a 300mm focal length)
In the old days, it was probably a good idea to avoid shooting at shutter speeds slower than one divided by the focal length of your lens. In other words, your minimum shutter speed using a 400mm lens would’ve been 1/400 of a second.
However, technology has moved on, so you don’t need to place such severe limits on your settings. Most lenses now have one, two or even three modes of Vibration Reduction/Image Stabilisation, and mirrorless cameras now have In-Body Image Stabilisation (IBIS).
As a result, you can now shoot at shutter speeds anything up to eight stops slower. That’s the difference between shooting at 1/30 of a second instead of 1/8000!
Of course, it depends on which camera and lens combination you own, and a slow shutter speed can only compensate for camera shake, not the movement of your subject, but it’s still a massive benefit.
Don’t always shoot at the lowest possible ISO
Yes, you can get the best possible noise performance, colour rendition and dynamic range if you use your camera’s lowest native ISO (usually 64 or 100), and that’s what studio photographers do all the time. However, that’s because they can use flash or strobes to brighten the scene. Most wildlife photographers either can’t or won’t do that in the field, so the ambient light is all that’s left.
If you’re already shooting wide open and there isn’t enough light to compensate for camera shake or freeze the action with a high shutter speed, the only option is to increase your ISO—or miss out on the shot entirely!
This is not a disaster. After all, there’s still a good chance you can ‘rescue’ the image in post using noise reduction software, such as Lightroom, Photoshop or Topaz Photo AI.
Don’t set auto ISO limits
The same goes for setting an auto ISO limit in the menu. The idea is to stop yourself from taking shots at ridiculous ISOs, but wouldn’t you rather have a shot of a crocodile biting off a lion’s head at ISO 12,800 than nothing at all?!
Admittedly, you can program some cameras to tell them to widen the aperture or slow down the shutter speed if you’re in danger of exceeding the ISO ceiling, but that just hands back control to the camera. As a result, you might not get the image you want—especially if it’s an action shot that needs a high shutter speed.
Don’t use extended ISOs
Most modern DSLRs and mirrorless cameras have a central range of native ISO values plus extended ISOs at both ends. These are obviously useful in certain circumstances when light levels are either very low or very high, but they’ll add noise to your images.
Don’t use in-camera noise reduction
Many cameras give you the option of noise reduction for long shutter speeds or high ISOs, but this isn’t the best way of reducing noise. Only the former actually affects Raw files, but it’s still good practice to turn off these settings in the menu.
In Post
Dos
Use noise reduction software
There are lots of good noise reduction software packages available these days, and they’re all pretty cheap, so there’s no excuse for not cleaning up your images. In the past, I used Topaz DeNoise AI and Sharpen AI, but Lightroom’s latest Enhance feature is even better, reducing noise without producing ugly artefacts—even if it does take around 30 seconds for every image!
Add grain to make images more realistic
If you’re really struggling to reduce noise while maintaining detail, you can always add a little bit of grain. Most programs give you that option, and it’s a good way to remove the artificial silky smoothness of an image that’s had too much noise reduction applied.
Use masking when sharpening images or reducing noise
If you use sharpening, clarity or texture in Lightroom, it’s very easy to sharpen the noise as well as the detail! That’s obviously not what you want, so it’s better to use the masking tool to restrict sharpening to your subject.
The easiest way to do it is to hold the option (or Alt) key down while using the masking slider. The image will become black and white, and the areas to be sharpened will be brighter than the ones ignored. You can then make sure any lines on your subject are bright while the background is mainly black.
If you want to reduce noise instead, you can still use masking. Nowadays, Lightroom has AI masking features that include one to select the background, so you can apply any noise reduction selectively without affecting the subject.
Convert to black and white
"Is this close enough...?" (taken at 3200 ISO)
One way to avoid the colour noise and poor colour rendition associated with high ISOs is to switch to black and white. Without any colour to worry about, you can focus on composition rather than noise reduction.
Don’ts
Don’t crop more than you have to
When it comes to noise, cropping has the same effect as magnification. That means you should try not to crop noisy images if you can avoid it. Yes, you might want a tight close-up of your subject, but would the image quality hold up? Wouldn’t it be better to settle for an environmental portrait showing more of the animal’s surroundings?
Don’t make your images too smooth
Noise reduction is useful, but you shouldn’t push it too far. If you do, you’ll get super smooth images that have very little detail and just don’t look natural. It’s all right to live with a little bit of noise in the background.
Don’t push the exposure slider too far
If you do end up with an under- or overexposed image, it’s usually possible to brighten or darken it in post without losing too much image quality—especially if it’s too dark. If you shoot in Raw, it’s much easier to retrieve detail from crushed blacks than it is from blown highlights.
However, if you try to go beyond a couple of stops (ie multiplying or dividing the brightness by four), you’ll probably end up with a very noisy image.
Verdict
Dealing with noise can be a pain, and there isn’t just one solution to the problem. However, the most important thing is to understand what it is and what causes it so that you can take appropriate steps to avoid or remove it.
It starts with the equipment you buy, and high-resolution cameras and fast lenses can cost a bomb. However, you can still avoid noise in camera by choosing the right settings and following a few simple dos and don’ts.
After that, it’s about investing in a decent noise reduction program and finding out how to make the best of a bad job!
By the way, if you’re looking for the facts on noise reduction, you could do worse than watch a few videos by Canadian wildlife and Nature photographer Simon d’Entremont. I did the same, and that was my inspiration for writing this post!
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