The exposure triangle is a term used to explain the elements that work together to create a well-exposed photograph. It has to do with the amount of light let in to the camera and the three components used to control it: aperture, shutter speed and ISO. Aperture refers to the opening in the lens and how large or small it is. The numbers representing aperture are the f stop numbers and the larger numbers represent a smaller opening. Shutter speed is how long the film or sensor is exposed to the light and the ISO is the film or sensor’s sensitivity to light. All of these elements can be adjusted to give different results. Here’s where you will have to venture out of auto mode and begin to play around if you want to learn the effects of changing these settings.
I am exploring ISO today and these shots taken at dusk in Zurich illustrate the effect simply changing the ISO can have on your result. These photos are shown how they appeared straight out of the camera. The aperture, f/7.1, and shutter, 1/50, settings are the same on all the photos. The first is with an ISO of 1000:
The lower the ISO setting the less grain will be introduced in to your photo. In the middle of the day, when there is plenty of light, using an ISO setting of 100-200 will give clear, colorful photos.
The ISO can be low and the f stop high and there is no problem capturing enough light to obtain a good exposure. When looking to the sky, I like to use lower ISO numbers to obtain true colors with low grain, or noise.
Sometimes, a darker mood is the goal.
Next week, I will consider the effects of a higher ISO and how it can be utilized in low light situations.