One question that recently came up on a trip to Cuba was how to deal with busy street scenes. Or, in other terms, how to clean up the shot. One simple answer to this question is change your angle of view. But what does that really mean? Imagine this scenario. You want to photograph part of a old car on a busy street in Cuba, but the background and sides are busy with daily street life. You could just zoom in from your position, but this would change the size of the subject. A better solution is move your position by walking back or forward. This will change your angle of view, but you can keep you subject size the same.
Here is what happens when I move approximately twice the distance (I moved from 5 feet to 10 feet away) from the subject and shoot at 50mm at F4. The subject is basically the same size, but I have narrowed my background down and changed the bokeh quality.
Next I put on my 105mm, roughly twice the focal length of my 50mm, and moved to approximately 20 feet away. Once again the subject is the same size, but the background in more narrow and more blurred.
Finally I put on my 300mm and shot at F4 even further away, but with the subject size the same. Now the angle of view is very narrow and the bokeh quality very different. Going back to the car on the street, by moving my position I can control how much of my background is in the image by narrowing the angle of view. And I can affect the bokeh quality as well. It is easy to stand at your tripod or zoom from your position, but don’t forget basic camera craft. Move your position to change your angle of view and bokeh.