Exercise 1 - Focal Length and Angle Of View

For this exercise I've used the Nikon D200 with the Nikkor 18 - 200 mm VR lens. Very useful when dashing out between showers, as the VR enables reasonable results without a tripod at long focal lengths.
I chose the Buddha that sits in the orchard at the end of our rear garden as the subject.

The first image was taken with both eyes open until the image through the viewfinder appeared to be the same as that seen by the naked eye. The focal length for this image was 56 mm. f/5.6, 1/125 sec.
When printed at A4 the photograph needed to be held at a distance of 26 cm from my eye to have the sizes equal.

The second image taken at 18 mm. This obviously has a much wider field of vision and the Buddha seems to be much further away - in fact the whole garden appears to be longer than it actually is. This image includes unwanted areas (houses in the background, parts of flowers in the lower terrace etc.). There is a degree of distortion in the perspective lines at this setting. The whole image is in focus at this setting - a much greater depth of field.
The amount of light required for the correct exposure is reduced, with a smaller aperture for the same shutter speed - the first image did not have the sky or other light areas to compensate for. f/6.3, 1/125 sec.
When printed at A4, the photograph needed to be held at 2 cm from my eye to have the sizes equal.

The third image taken at 200 mm. With the longer focal length, Buddha is brought forward into the frame. At this magnification much more detail can be seen - bluebells can now be identified, flaking paint on his robes and look at the length of the grass!!. There is no sign of distortion in this image, but the focus is much tighter, so areas behind the point of focus (Buddha) become blurred - a narrower depth of field.
As this image was taken in the shade, the shutter speed was slower than the first image with the same aperture setting to receive sufficient light. f/5.6, 1/90 sec
When printed at A4, the photograph needed to be held 100 cm from my eye to have the sizes equal.

This exercise clearly shows the relationship between field of vision and focal length - it also shows why the smaller focal lengths are named 'wider' lenses. It's also interesting to see that photographs taken at longer focal lengths need to be viewed from a longer distance to make the sizes seem equal.

It was interesting to note that the 'standard' position of the lens was very close to that of a 35 mm camera - I would have expected the position to be around 33 mm to give the 'standard' 50 mm This could be down to the setting of the viewfinder, which has been adjusted to my own vision requirements, or magnification in the viewfinder, or the optics my own vision.