First of all, lets look at what is digital noise and how does it occur... Digital noise is brought on by high ISO levels produced by your camera. The term ISO is a measure of your camera sensor's sensitivity to light. Your digital camera lets you increase the ISO level so that you can take photos in low-light situations.
Keep in mind that there is always some noise in your photos, even at your camera's lowest ISO, but the higher you increase the ISO levels, the more noise results in your image.
Here is a simple tip, if possible shoot at a lower ISO. This reduces the chance that the camera will amplify the existing noise in an image. Luckily cameras are getting better all the time. Recent DSLR models can go as high as ISO 24000+ without noise being a major problem – only a few years ago ISO400 would often cause some problems, but today I am shooting many times at 800 to 1200.
But lower ISO leads to one of the largest culprits in creating digital noise, shooting long exposures. The longer the exposure time, the hotter your camera sensor gets, the more digital noise you will find on your final image.
Most DSLRs come with the recommendation that they work best between 0 and 40C. You should remember that. Keeping your camera cool (or more specifically your image sensor) will help prevent contaminating your sensor. Don’t leave your camera where it will get hot like in your car or in a bag in the sun.
If you are shooting long exposures or burst mode, well, this just can’t be helped… to eliminate the noise here you might just have to depend on post editing software.
And last, the one thing many photographers struggle with is underexposing. I would bet that you'll almost always see more digital noise in darker areas of photos and in images that are underexposed. Which for older photographers that learned in film days, and were taught to underexpose, this is a mind shift.
To compensate for this… Do what is referred to as, “Shoot to the Right” – You will often hear experienced photographers explaining the value of slightly over-exposing your images. We teach this on our snowy workshops all the time.
Darkening over exposed areas is usually a better option for digital shooters in post-production. So the next time you are out, and you are worried about noise, try over exposing a stop or two while shooting. Using your EV compensation is a quick way to slightly over expose.
This is something you are always going to struggle with… but keep one thing in mind, “Wouldn’t you rather get a great image with some digital noise, than an out of focus photo with no noise?”
Thanks for reading