Exercise Title: Learn how aperture and distance affect your image
Purpose: When you take control of depth of field by understanding the relationship of camera to subject to background along with your choice of focal length and aperture then a world of creative decisions are available to you.
Method: Put your camera on a tripod and have the camera roughly 10-15 meters away from a background of your choice. The background needs to have detail so you can see the effect of out of focus behaviour.

Get your subject, a body is good as they can move themselves, if not, anything else you can focus on and easily move will do. Perhaps a folding chair or another camera on tripod

Place the subject halfway between you and the background and take your pics at f16 and f4 with a wide angle and a telephoto lens.

Now move the subject much closer to you and take pics again at f16 and f4 with a wide angle and a telephoto lens.

Analyse: Review your results. Share your images of your sharpest and most blurred backgrounds, explain what is happening and when you are likely to use each scenario for your photography.

Feedback: It was good doing this exercise immediately after our day together as it helped to cement the idea in your mind of how our choice of lens and aperture affect the final image. The two main things to remember are: -
1: The closer we get the object to the lens and farther away from the background the greater the background blur will be. The relative distance of subject to camera will have more effect than simply changing the aperture :-)
2: As you noticed f16 does not give very sharp results. This is because of a lens issue called diffraction. Your best bet for consistently sharp images is to keep your aperture in the range of f4 to f11. 

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