Let’s begin with the obvious way to keep shooting when the lights get low: raising the ISO (Figure 8.1). By now you know how to change the ISO by using the ISO button and the Command dial. In typical shooting situations, you should keep the ISO in the 100–1000 range. This will keep your pictures nice and clean by keeping the digital noise to a minimum. But as the available light gets low, you might find yourself working in the higher ranges of the ISO scale, which could lead to more noise in your image.
Everyone has a different tolerance for digital noise, so experiment a bit with different ISO settings and see what your limit is. My tolerance depends on my subject. For my landscape photography I have a very low tolerance for digital noise, but for street photography I have been known to let it slide here and there.
Now, you could use a flash and try to avoid bumping up your ISO, but that has a limited range (15 to 20 feet) that might not work for you. Also, you could be in a situation where flash is prohibited, or at least frowned upon, like at a wedding or in a museum.
And what about a tripod in combination with a long shutter speed? That is also an option, and we’ll cover it a little later in the chapter. The problem with using a tripod and a slow shutter speed in low-light photography, though, is that it performs best when subjects aren’t moving. Besides, try to set up a tripod in a museum and see how quickly you grab the attention of the security guards.
So if the only choice to get the shot is to raise the ISO to 1000 or higher, make sure that you turn on the High ISO Noise Reduction feature. This custom menu function is set to Standard by default, but as you start using higher ISO values you should consider changing it to the High setting.
Raising the noise reduction to the High setting slightly increases the processing time for your images, so if you are shooting in continuous mode you might see a little reduction in the speed of your frames per second.
Don’t let digital noise stop you from taking a photo. There are tons of wonderful postproduction software programs that help remove digital noise from your image.
Noise reduction saves space
When shooting at very high ISO settings, running High ISO Noise Reduction at the Normal or High setting can save you space on your memory card. If you are saving your photos as JPEGs, the camera will compress the information in the image to take up less space. When you have excessive noise, you can literally add megabytes to the file size. This is because the camera has to deal with more information: It views the noise in the image as photo information and tries not to lose that information during the compression process. Thus, more noise equals bigger files. So not only will turning on the High ISO Noise Reduction feature improve the look of your image, it will also save you some space so you can take a few more shots.