Most digital cameras have a setting (sometimes called ISO or ASA) which allows the photographer to adjust the sensitivity of the sensor. If the sensor is more sensitive to light, then a faster shutter speed can be used, which is very handy when shooting in low light conditions. This is the digital equivalent of using a roll of film with a different sensitivity to light. The negative tradeoff is that the higher the sensors sensitivity to light, the greater the amount of noise that will be generated.

Both images below are 100% crops, shot using a digital camera, handheld at 1/60th, 70mm at 800 ISO. If I had not increased the ISO to 800, I would have needed a much slower shutter speed. But equally, at 800 ISO, when shooting in low light conditions, a great deal of noise was created as you can see in the image on the left. The image on the right has had the noise removed using noise ninja.

To the casual photogrphaher, noise is not a problem. But when it comes to microstock photography, noise is a very big issue, and for a good reason. Buyers who purchase images from microstock photography websites expect the images they are purchasing will be of the highest quality possible, and free of noise. Whilst some buyers purchase images for web use at a low resolution, it is also true that other buyers will purchase your images with the intention of creating a large poster, perhaps the size of a person, or a car, or bigger. If your stock photos contain noise then they will be of little or no use to the buyer. Noisy stock photos will be not be accepted by the stock photography web sites.

Shooting in low light conditions creates more noise, as does shooting in warm environments. Whilst at the north pole, one photographer noticed that his photos contained almost no noise at all due to the exceptionally cold air. When working in the studio noise is less of a problem as you can turn your ISO/ASA down to the lowest setting, and with a tripod or flash the desired shutterspeed can be achieved easily enough.

If you want to sell more photos then you will often need to adjust the colours and levels of your photos, and whilst keeping them looking natural you will want to enhance them, making them more vibrant, alive and colorful. The more impact your photos have the better they will sell. But by adjusting the levels of your images in photoshop even more noise/grain is created, and the more noise your photos contain the greater the chance that they will be rejected by the stock photo websites.

Although you can take photos which will be accepted by the stock photography web sites without a noise removal tool, I could not imagine shooting stock without one. I personally use Noise Ninja. Some people use Neat Image. Noisa Ninja is fantastic, and no stock photographer should be without it. It is very powerful, very clever, easy to use, and gives the photographer total control over how much or how little noise is removed.

Some digital cameras (usually the cheaper ones with smaller sensors) feature an inbuilt noise removal tool. ie, the camera attempts to remove noise itself. This automated feature should be turned off at all times, and care should be taken when buying a new digital camera to ensure that this feature can be toggled off. When noise is removed, detail is removed and data is lost. One needs to be very careful when removing noise to ensure that photos do not suffer from overuse of the noise removal tool. Naturally, this is something the reviewers at stock photo websites look for.

I use a very small percentage of the power of Noise Ninja, as should you.