In this article I’ll be explaining just the basics of how ISO, aperture, and shutter speed works. Knowing how your camera handles light will give you much more control over how you take your photos.
ISO is a way of measuring the sensitivity of film to light. The lower the ISO number, the less sensitive. Although it applies to film, the same concept applies to digital cameras. At ISO 800, the film is quite sensitive, and therefore does not require as much light as ISO 100 would need to take the same picture with similar exposure.
The downside to using a larger ISO is the amount of noise (those little annoying pixels) the image will produce. While you may be able to get a faster shutter speed with a higher ISO, the image will have more noise.
No one wants that in their shots. Higher end cameras handle noise much better than the cheaper ones.
Since I like landscapes, I shoot at the lowest possible ISO, and use a tripod so that I can use the aperture and shutter speed that I need. Action shots usually require a higher ISO.
The aperture is the opening of your lens that allows light to make it into the camera. The smaller the number, the more the opening increases. Here’s a good example from Wikipedia:
The larger the opening, the more light is allowed in.
There are a few reasons why aperture matters. There is a technique that people use to blur the background while keeping the main subject in focus. Basically, the larger the aperture, for example f/2.8, the more the background will blur. The blurring is called ‘bokeh’. I’m still not sure how to pronounce it because it sounds funny every way I try. This is usually good for portraits, because you don’t want anything else in the background to distract you from your subject.
You may have come across a problem where you want multiple subjects to be in focus, but they are at different distances from the camera. In the previous paragraph, I said that a larger aperture would increase background blur. In this case, a smaller aperture (smaller opening, not number) will blur less and keep things more in focus. Also, apertures around 8.0 tend to be the sharpest your lens will shoot. As you can see, this can be very useful under certain circumstances such as landscapes. It’s a lot to take in and I have a writing skills of a four year old, so go experiment yourselves!