Photographing at night or in dark places is not always easy, however, like in the past, we can “change” the speed of our film. This is called “sensitivity” and is indicated by the acronym ISO. It varies from 200 (good light conditions) to over 6400 (bad light conditions) in medium quality cameras. To use an automotive metaphor, it would be similar to when we downshift to go uphill. We often change the ISO to manage exposure time and shutter speed in order to obtain the perfect exposure. In a digital camera, a high ISO can create a grainy image similar to film, which is less definite, a bit misty and sometimes quite romantic.