Let's Talk ISO

ISO is pretty important. It is one of three elements that make up the exposure triangle. This is quite tricky to demonstrate with photos so you will have to look closely at the pictures below. First off a photo taken with the lowest ISO setting on my camera (100):

The low ISO setting gives a lovely smooth photo. The details are sharp and the blur is smooth. This is exactly what to look for in good photo. Now take a look (a very close one) to the below photo taken with the highest ISO setting on my camera (3200):

Now admittedly you have to look closely to see the difference but its most obvious in the background. The blur, which is supposed, to be smooth is a little grainy.

Now I hear you ask a question here, if a high ISO makes a photo grainy why would you ever use that setting? Now this is a good question because in natural light (the best kind) a low ISO setting is perfect and gives the best results. However when you set your camera to a higher ISO it becomes more sensitive to low light levels. This means when it is darker in the shadows or you are taking photos at night using a higher ISO can result in more details appearing in your photo.

So remember this:
Low ISO = Less grainy photo, great for good light
High ISO = More grainy photo, great for low light

A time to use a slightly higher ISO would be if you have to shoot inside, for example at a wedding or family gathering or you are photographing your home. You may need to use an even higher ISO if you are at an evening or night party and need the maximum sensitivity to light, your photos will be a little grainier but the overall outcome will be better.

Take a look at my post on the exposure triangle if you want to see how ISO works in balance with shutter speed and aperture. Zoe x