There are three main camera settings that are responsible for a correct exposure: ISO, aperture, and shutter speed. These three settings are inseparable; if you change one of them, it affects the other two. When you are able to understand and use these settings, you have a lot more control over the resulting images. Today’s blog post is the first in a series of posts that will help us understand these three settings better, and will explore how to put them together to create beautiful images.
The first setting we’ll tackle is ISO. Most cameras allow you to adjust your ISO, including point and shoot cameras. The ISO setting determines how sensitive your camera’s sensor is. The higher your ISO number, the more sensitive your camera is to the light coming through the lens. This is particularly helpful in situations where not a lot of light is available, such as inside your house. Another reason you might need to increase your ISO is if you are using a smaller aperture, which means your lens doesn’t open up as wide when it takes the picture, and therefore is not letting as much light in.
In this example, I was in my living room, using only the light from the window, so I had to bump my ISO up to 800.
So why don’t we just keep our ISO as high as possible all the time? When your camera is more sensitive to light, it is also more sensitive to interference or “noise”. This noise will make your images look grainy.
Here you can see the difference between a low ISO (100) and a very high ISO (3200). It is especially visible in the darker areas of the photo, such as the background and the pupils the cat’s eyes.
At this size, it may be hard to tell, so here are the same photos more closely cropped:
A good rule of thumb for setting your ISO is to keep it as low as possible while still getting a correct exposure. One word of caution, though: don’t keep your ISO low at the expense of your exposure! Underexposing your image and then lightening it up in a photo editing program will create more grain than if you just use a higher ISO in camera.
You can see how much grain is added to this picture when I lightened the underexposed image in photoshop.
Again, a closer crop of each so you can really see the difference:
Try experimenting with your ISO settings this month. Once you get the hang of it, you will see a difference in the quality of your photos and possibly the speed at which your camera takes them. Once you’ve mastered ISO this month, we’ll talk a bit about aperture next month!