You’ve all had digital pictures with ‘noise’ in them… do you want to know why? Low light photography, it’s a tricky beast, right? You’re out there, trying to capture the stars or maybe a dimly lit room, and bam! Grainy, speckled images. It’s like the camera’s playing tricks on you. But what’s really going on? Well, it’s not magic, and it’s not your fault either. It’s all about the photons, the ISO, the shutter speed, and a bunch of other techy stuff. Don’t worry, I won’t get too jargony on you (not yet, anyway!). So grab your camera, and let’s dive into the world of low light photography and digital noise. Trust me, it’s brighter than it sounds, LOL!
How Do Digital Cameras Work?
Ever wondered how digital cameras turn a real-life scene into a digital image? It’s all about those little thingies called photons, the tiny particles that make up light. When you snap a picture, the camera’s sensors get bombarded with these photons. These sensors are like little light catchers, and they’re analogue devices, meaning they deal with continuous signals. They take in the photons and turn them into digital data. It’s like translating a beautiful poem from one language into another, but with light!
Now, these sensors are pretty smart. They’re sensitive to three different colors of light: Red, Green, and Blue (RGB). Think of them as the primary colors of the digital world. The cells that get more photons are like the popular kids at school; they have a higher charge and are considered ‘lighter.’ The ones with fewer photons? They’re the ‘darker’ ones. It’s like a dance of light and color, and the sensors are the choreographers, turning the analogue signals into a digital masterpiece. Next time you take a photo, just think of all the magic happening inside that little device!
Gain: Amplifying Weak Digital Signals (Low Light Noise)
Now, what happens when you take a photograph in a really dark place? Once you’ve opened up your aperture to the max, and used the lowest shutter speed possible, you turn the ISO up, right? And voila! Your sensor is more sensitive, right? Naah! The sensor can’t really adjust its ‘sensitivity’; instead, what your camera does is, it turns up the amplification of the photons that are received. Making them seem brighter. In audio, this is called ‘gain’.
So why are higher ISO photographs so grainy, and noisy? If you guessed “because of the amplification,” you’d be right… It’s similar to amplification on your stereo. If the signal level is low, the more you amplify it, the more likely it is that you’re going to amplify the background static too. And this will give you lower quality sound.
What is Digital Noise?
Digital noise refers to the random variation of brightness or color information in images, creating a grainy or speckled appearance. It shows up in two main forms:
- Luminance noise: which affects the brightness of pixels, and
- Chroma noise: which affects color
Your camera’s sensor has a basic charge, so if we turn up the amplification because the signal level (number of photons) is too low, this charge, along with the charge from neighbouring cells interferes, creating ‘noise’ or ‘static’. This ratio of ‘signal’ to ‘background noise’ (or static) is called, quite simply, Signal to Noise ratio. If the signal to noise ratio is high, you’ve most likely got a clear picture, if it is low, you’ll have a noisy one (how about that … next thing you know, I’ll be talking about loud-mouthed pictures!).
Causes of Digital Noise
- High ISO Settings: Increasing the ISO amplifies the sensor’s signal, leading to noise.
- Long Exposure Times: Prolonged exposure to light can cause noise, especially in warmer conditions.
- Sensor Size and Quality: Smaller sensors and older technology may be more prone to noise.
- Environmental Factors: Temperature and humidity can also affect noise levels.
A Workaround to Reduce Digital Noise in Low Light Photography
Give the photograph more light. Seems like a simple workaround to , right? Well, not quite… There are significant challenges to adding more light to a scene as the size of the scene grows larger.
With indoor low light photography If you’re indoors, then you could use direct, diffused, or reflected flash light. You could even use a brighter light source by using brighter bulbs or turning on more lights. If you’re shooting hand-held birthday photos, adding more light with flashes or constant lights would be a better option than trying to use a tripod.
Night Nature, Landscapes and Cityscapes
You can’t always add light when shooting a landscape at dusk, or at night. Although we sees photos of photographers using drones to light up rocky features, this is a technologically challenging task, and isn’t possible for everyone or everywhere. In this case, many photographers use their creativity to show the movement inherent in nature around us… The movement of water, creating beautiful streaks of flowing water, or blurry waves.
If you’re photographing the stars, and the night sky, then you’re out of luck – you can’t light up the sky, can you? Instead, you could use a tripod, and allow more light to accumulate over time, with longer exposures. This then has the issue of causing blurring of the stars as the earth rotates. Astrophotographers bypass by using tracking mounts, that move the camera to compensate for the rotation of the earth, keeping the stars stable in the camera’s viewfinder for many hours at a time.
But you can’t always have things go your way. There’s usually a price to pay for every perk, and part of low light photography is understanding the limitations and abilities of your particular equipment. Some limitations can be overcome by equipment, others by post-production techniques, and yet others simply can not be overcome, and must be worked with, or worked around.
Low Noise, High ISO, Fast Shutter Speed – Possible?
Ok, now don’t ask me how to keep the S/N ratio high even with low light and a high shutter speed!
That’s something that the engineers who built the cameras will have to figure out, and as cameras get better they manage to pull off this magical feat! For the moment though, what I can tell you is to use lower ISO numbers, and only rarely use higher ISO numbers … only you absolutely have to. This way, you’ll have significantly fewer noisy pictures (always keep in mind that a good picture is meant to be seen and not heard, LOL).
Photo Noise Reduction Plugins (and AI Noise Reduction)
In the world of digital photography, AI noise reduction plugins for photos are seemingly magical. RAW files have so much information from the camera sensor that they’re able to provide sufficient information for AI noise reduction tools to work their magic even on photographs taken in very low levels of light.
Here are some AI Noise reduction plugins for photographers.
- Topaz Labs DeNoise AI
- DxO PhotoLab 6
- ON1 NoNoise AI
- Adobe Photoshop Lightroom Classic CC
- Skylum Luminar Neo
You can use AI photo noise reduction as a backup measure if you have to push the ISO up to get the photograph and have no choice.
Low Light Noise – Gone Forever
I’ve tried hard to keep this post jargon-free. Do let me know if you would like a more techie explanation, and I’ll give you the whole story with diagrams and tech-talk.
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