Choosing focus

I am part-way through a long post on personal knowledge management, which may see the light of day sometime this century. In doing so, I have been reflecting on something that I mention a lot in these posts: focus. I have been guilty of using the word in a very loose “I know it when I see it” fashion, but I am beginning to realise that a bit more explanation is in order.

I have an interest in photography, where focus is clearly a part of taking good pictures. However, there is more to it than that. Cameras come with a number of settings that affect the image — what is actually in focus. All of these settings require the photographer to make choices, which are similar to the choices we make when we talk about focus in a more general sense.

The first choice to be made is selection of a lens (or a zoom setting, for lenses with a variable focal length). Is the subject of the image distant or close? Do you want to concentrate on a single item or a large landscape? Variants of these questions can be used when considering personal focus as well. Is your objective finely detailed and distinct? If so, make sure you concentrate on it to the exclusion of other things (the telephoto or macro lens). Is it more diffuse — exploratory, perhaps? Then use a more inclusive approach (a wideangle lens).

Then there is a set of choices that are all interlinked — aperture, shutter speed, ISO (sensitivity or film speed, for non-digital photography). These need to be set to take into account the depth of field required (how much the subject stands out from the background or foreground), whether the subject is moving, and how much ambient light there is. Again, similar considerations can be borne in mind in a non-photographic context. Does your objective stand apart from other issues or do you need to consider it in a wider context? Are things moving fast, so quick action is required, or is a slower, more reflective pace acceptable? How much information is there on the topic — do you need highly sensitive receptors or is a strong filter preferable?

Once you have thought about all those variables, it is time to compose the image. Like everything else, careful thought about these preparatory questions improves the quality of the output. Equally, whether the output is good or not, it can be used to refine the initial settings before repeating the action. A plan-do-refine approach can also be useful in other contexts too. I can’t pretend to be a great photographer, but I do try to get better.