The first two assignments dealt with deep depth of field and shallow depth of field.  Small apertures (f/16 and smaller) create a deep depth of field and allow the picture to tell a story relating things that are close by to objects in the distant background.  Wide apertures (around f/5.6 and wider) isolate objects at a certain distance from the lens and blur everything else, giving the photo a singular theme.  But what should you do if everything in the frame is about the same distance away, say something (maybe a leaf) lying on the ground, or a landscape where everything is way off in the distance (everything is essentially an infinite distance from the lens)?  What aperture do you use?

In Understanding Exposure Bryan Peterson calls these “Who Cares?” apertures.  It doesn’t really matter from a depth of field point of view which aperture you use (from a depth of field point of view) when everything is the same distance away, but there are other considerations as well.  The main consideration when depth of field no longer matters is sharpness.  Lenses have a sweet spot when it comes to aperture and it is usually around f/8 or f/11.  Wider apertures tend to scatter light and thus reduce sharpness.

Another way sharpness is affected by wide apertures is actually influenced by the depth of field.  As discussed in the shallow depth of field assignment the margin for error on your focus distance right is quite small so if you don’t focus just right for the photo where everything is the same distance away, your entire photo will be blurry, or at least not as sharp as it could be.  Going the other way, a very narrow aperture (with a deep depth of field) will give you a lot of leeway with the focus but it often reduces the amount of light getting in to the point where you now need a slow shutter speed.  It may get to the point that you can no longer use a tripod.  So, the solution to these two problems is to use an aperture somewhere in the middle, say f/8 or f/11.

You would need to experiment to determine the actually sweet spot for your lens, but it usually somewhere around f/8 or f/11.  Some examples of situations where these “Who cares?” apertures are used are things like portraits against a wall, something on the ground or hanging on a wall, a sign, a landscape with no foreground, etc.

The Assignment

The assignment for this one should be obvious.  Take some pictures using a middle of the road aperture where the depth of field doesn’t really matter and the intent is for the entire photo to be sharp.  Make sure it makes creative sense to do so.

I know I have some photos the meet this criteria already so I may look for some examples from my previous work as well as going out to get some new shots.

Click here to see all of the assignments.

Click here for the results so far from this assignment.