Let’s look into the whole picture.
You should always be aware of everything that is present in your frame, but this takes time and a lot of practice. When you first begin to shoot, your primary concern is going to be your subject. While this may seem to make sense in the beginning, you’ll come to find as you look at your photos the ones you initially thought were great are not so good due to distractions in the background. You might even think – “How did I miss that person walking by in the street behind my model?” Well, the answer is simple: you were more focused on the model and not the whole picture.
This is sort of natural because we focus on what’s most important to us at any given moment and filter out unimportant sensory input. If we don’t filter out our brains would become overwhelmed. This is exactly why it’s important to recognise that photography is a skill, and you can’t just snap a photo to have it be good. Part of being a good photographer is learning to become hyper-aware of your surroundings. However, it is hard to rewire your brain, so don’t feel bad if you always have those photos that have something in them you didn’t notice. I know it still happens to me.
That said, you can’t usually exclude the background completely but you can control it. How? With a depth of field. A depth of field basically means the amount of perceived distance between the nearest and furthest objects or subjects that are in focus in a photograph.
If you have a shallow depth of field, you’re going to have your camera set on a low aperture such as f4 or f8. A shallow depth of field makes things look dreamy in the background and the focus is mainly in the foreground. On the other hand, a deep depth of field provides more focus all the way through a photo. The higher f-stop the sharper the photo, to the point where you can actually have everything in an image in focus if that’s the look you’re looking for.
You’ll often find that changing your position is enough to replace a cluttered background. that compliments your subject nicely. Or you can use a wide lens aperture and a longer focal length to throw the background out of focus.
It all depends on whether the background is part of the story you’re trying to tell.