Exercise 2: Focus with a set aperture

Wherever we turn the attention of our eye we find objects in focus.   While you are looking at these words, try bringing your attention to things on either side of the screen.  You are aware of their presence, maybe their shapes and colors, but they are not in focus.  Now look at something across the room and notice that the things close to you fall out of focus.

In this respect, your camera functions much the same as your eye when set at low apertures.  It tends to focus on objects at one distance, but not more than one.  (At high apertures you can achieve with your camera something you cannot with your eye, focusing on everything within the frame.)  The object of this assignment is to demonstrate the camera's focusing ability, to note how to change the area of focus with a fixed aperture, and to investigate the relative area of focus. 

I set up two stacks of books and in front of them my tripod mounted camera.  I shot in Aperture Priority Mode using the camera’s manual focus feature to compose three photos, one each focusing on foreground, midground, and background.

1.10, f4.8, ISO640, background focus

1.13, f4.8, ISO640, midground focus

1.13, f4.8, ISO640, foreground focus

Freeman asks us to mark on each photo the areas of sharpest focus, which is what you’ll see in the photos below.  Perhaps you’d like to take a look at the ones above before proceeding.  Note the relative smallness of the area of clear focus at midground.  Even the spine of the Study of Religion text appears sharp at the extreme end of foreground focus.   This may be the result of the angle of the photo sensor.   Also note that even the corner of the spine of the bottom text in the background is as sharp as the Atget text.  The implication?  It’s not just what’s in the top of the viewfinder that comes into focus, but everything at that depth. 

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