Uses of different focal lengths and lenses.
The differences between 50mm and 35mm, the crop factor, and which suits which shooting style when picking your first prime lens.
Which focal length — 24, 35, 50, 85 and 100mm+ — suits which type of shooting, plus choosing between prime and zoom lenses.
How aperture values from f/1.4 to f/22 affect light and depth of field, explained with examples for beginners.