ISO and Image Noise with the Nikon D3300
Ideally, you should always use the lowest ISO setting on your Nikon D3300 to ensure top image quality. As ISO increases, making the image sensor more reactive to light, you increase the risk of producing noise.
Noise is a defect that looks like sprinkles of sand and is similar in appearance to film grain, a defect that often mars pictures taken with high ISO film. This figure offers an example.
Sometimes, though, the lighting conditions don’t permit you to do so and still use the aperture and shutter speeds you need. Take the rose image as an example. When these pictures were shot, the photographer didn’t have a tripod, so he needed a shutter speed fast enough to allow a sharp handheld image.
He opened the aperture to f/6.3, which was the widest setting on the lens he was using, to allow as much light as possible into the camera. At ISO 100, he needed a shutter speed of 1/40 second to expose the picture, and that shutter speed wasn’t fast enough for a successful handheld shot.
You see the blurred result on the left in the figure. By raising the ISO to 200, he was able to use a shutter speed of 1/80 second, which enabled him to capture the flower cleanly, as shown on the right in the same figure.
Fortunately, you don’t encounter serious noise on the D3300 until you really crank up the ISO. In fact, you may even be able to get away with a fairly high ISO if you keep the print or display size small. Some people probably wouldn’t even notice the noise in the left image in the first figure unless they were looking for it, for example.
But as with other image defects, noise becomes more apparent as you enlarge the photo, as shown on the right in that same the figure. Noise is also easier to spot in shadow areas of the picture and in large areas of solid color.
How much noise is acceptable — and, therefore, how high of an ISO is safe — is your choice. Even a little noise isn’t acceptable for pictures that require the highest quality, such as images for a product catalog or a travel shot that you want to blow up to poster size.
A high ISO isn’t the only cause of noise: A long exposure time (slow shutter speed) can also produce the defect. So, how high you can raise the ISO before the image gets ugly varies, depending on shutter speed.