Out Of Focus

This isn't a discussion of calculating depth of field, finding out best f-stops and dealing with diffraction. Rather it's a discussion of the whole business of whether everything should be sharp or not.

Let's look at some characteristics of having part of the image significantly out of focus.

1) it sure makes the sharp bits stand out
2) contrast in the blurred area is lower
3) specular highlights that might be distracting if sharp are blurred and not so white
4) details that would distract are hidden in the blur
5) progressive blurring (as in a portrait) makes you concentrate on the sharpest bits, usually the eyes)
6) out of focus results usually in smooth tonal transitions
7) lets not forget that accepting a shallower depth of field means a higher shutter speed or slower iso setting which may offer significant advantages
8) out of focus can actually be very attractive - there are whole discussions about bokeh and the ability of particular lenses to render out of focus areas attractively, but regardless of equipment and diaphragm shapes, blurred can be beautiful.

It's traditional in some subjects to try very hard for universal depth of field - ie the whole picture is sharp, while in birding and sports shots, photographers actually take advantage of the blurring to isolate the centre of interest.

Does this then mean that one shouldn't ever have blurring in landscapes, or that good depth of field isn't suitable to sports images? I can think of examples where the blurring was crucial to the landscape, the depth to a particular sports shot.

It might be time to start asking yourself is there a way to take advantage of shallow depth of field.

Extremely shallow depth of field, achieved generally with long lenses or really wide apertures or in macro situations. If most of your shots are sharp from near to far, perhaps you might want to deliberately try some out of focus blurring.