Generally, noise can be defined as aberrant pixels. This means that pixels that are not representing the colour, or the exposure of the scene correctly.
Noise comes into the images when you capture a long exposure image or shoot at a high ISO semodetting. But that doesn’t mean that you should never go over ISO 100 or do long exposures. as there are times that you may need to shoot in those conditions. Landscape photographers specifically shoot in low light all the time. The important things to be aware are of is how to avoid having too much noise in the image and, how to deal with it in the post production production process.
We’ve compiled a list to prevent noise occurrence in the photos and get noise free images all the time.
The ISO functionality in modern day cameras is great. You won’t see much noise occurring in the images, even up to ISO 1000. But, there might still be a little amount of noise at the higher ISO settings, so be aware of your exposure. Shooting at a lower ISO means you will have less noise in your image. Higher ISO settings tell your camera’s sensor to join pixels together to get more light. This joining effect can make your image look gritty and noisy.
So, how to avoid shooting at a high ISO? If possible, set your aperture to its widest setting i.e. f/2.8. If you are shooting in low light, use a tripod if possible, or you could use a flash. If none of these options give you the correct exposure, then you will have to push the ISO up higher. Also, do some test shots to find out at what level the ISO settings on your camera start to degrade image quality.
I know most people feel uncomfortable by shooting in RAW, but they shouldn’t be because RAW is a brilliant way to get the best out of your images, so be sure to use it. You don’t have to shoot RAW all the time, but when you notice that the light is getting a little too dark, switch to RAW. The reason is that JPEG images already have compression applied to them. This means that there is already some noise, and what is known as JPEG artefacts, in the image. Also, in post-production production, you’ll have greater flexibility in removing noise, and increasing exposure as compared to a JPEG file.
Adobe Photoshop Camera Raw has some powerful noise reduction tools
When digital cameras were first introduced in the market, they were pretty awkward at capturing highlights correctly. Many photographers would slightly underexpose the images in order to retain detail in the highlights. This meant that the shadow areas were very dark and when you tried to shift them up in Photoshop, the noise would become more visible. This has been hugely solved out now and the new generation of digital sensors performs in a great manner with handling highlights and shadows. As a result, you can expose in the correct without having to worry about the occurrence of noise in the shadows, or problems in the highlights.
Also, you can also overexpose a little so that the shadows are a bit brighter than regular and then you can shift the highlights down in Photoshop but remember not to overexpose too much, and keep an eye on highlights as the details may then be lost for good.
Long exposures make some of the most dramatic images, but if the exposure is too long, the sensor of the camera can begin to heat up and the pixels will render incorrect colours and exposure. You can still do long exposures, but again, be aware of how you camera handles the long exposure time. Does the image look too grainy? Test it out and experiment to see where your camera begins to struggle. Then make sure that you don’t shoot a long exposure for longer than whatever works on your camera. The key point here is to know the limits of your gear and shoot within those limits. This will ensure great images and easy image editing.
Long exposure images can accentuate noise in a scene
In most modern cameras there is a feature known as the High ISO Noise Reduction or Long Exposure Noise Reduction. It’s a nice thing as turning this on will allow you to shoot easily at a high ISO or do long exposures. The reason is simple, i-e, after the image has been captured, the camera will analyze the image by itself and look for any pixels distortion. It will then fix the pixels that are not properly rendered. This might takes some time, usually as long as the exposure time. So if you shot an image that was 30 seconds long, the camera will do an analysis and correction that will take up to 30 seconds. This may become impractical if you are doing 10 minute exposures, but it is worth doing on shorter exposures. If you have the time, do it on the very long exposures too, as it can improve the image quality.
Use in camera noise reduction for long exposures and lowlight images
The noise reduction sliders in Photoshop Camera Raw, are identical in Lightroom
Once you have captured your image, you should open it in Lightroom or Photoshop to see how it looks. It is a good thing to zoomin your image to 100% in order to observe the real details of the noise in the image. When you make any alterations, be sure to zoom in to 100% (1:1 in Lightroom), but also zoom out to see the full image to make sure that the whole thing looks good.
The sliders do the following: