Exercise - Focal length and angle of view:
The aim of this exercise is to explore focal lengths and find the 'standard' focal length for your camera.
The plan: I'm aiming to use the back garden as I can pick a spot that I can easily return to again and again. I'll use my zoom (18-250mm) and expect the 'standard' to be around 75mm. As I use an APS-C DSLR, there is a 'magnification' factor of 1.5. This doesn't actually magnify but crops the field of view, giving the impression of magnification but means the A4 prints produced will have a magnified effect.
'wide angle' 18mm, F/6.3, 1/60sec, ISO200
'standard' 70mm, F/5, 1/125sec, ISO200
Holding the A4 print at a distance where it is the same size as the scene gave the following results:
18mm - 18cm approx
70mm - 80cm approx
250mm - 260cm approx
Despite the margins for error the distance in 'cm' that an A4 print is held at to match the scene is remarkably similar to the focal length in 'mm' that the picture was taken at! Not a result I anticipated.
The 'standard' focal length is a much more comfortable viewing distance.