Find a location with good light for a portrait shot. Place your subject some distance in front of a simple background and select a wide aperture together with a moderately long focal length such as 100 mm on a 35 mm full-frame camera (about 65 mm on a cropped-frame camera). Take a viewpoint about one and a half metres from your subject, allowing you to compose a head shot comfortably within the frame. Focus on the eyes and take the shot.
Longer focal lengths appear to compress space, giving a shallower depth of acceptable sharpness, which is known as depth of field. This makes a short or medium telephoto lens perfect for portraiture: the slight compression of the features appears attractive while the shallow depth of field adds intensity to the eyes and ‘lifts’ the subject from the background. For this image Beryl and I found a white wall on a building around the corner in sunlight.
This made the lighting difficult and I have cropped out some shadow. Although as the screenshot below shows I did set the camera to a wide aperture (f/4) the white building does not really demonstrate the shallow depth of field.
I have zoomed in using Photoshop to check whether the focus is on the eyes as suggested in the task – while there is a catch light in the right eye they still look somewhat soft.
The following day I went to a local Wildlife Park for the purpose of taking photos for exercise 2.6 and think the image below does demonstrate the shallow depth of field and focusing on the eyes that this exercise required:
In this instance I was however using a telephoto lens with a focal length of 200, Av 5.0 and I had set a high ISO of 800 for sharpness as just prior to this there had been a hail storm and it was still gloomy.