Understanding apertures is important... just as important as understanding shutter speeds. The web and books are full of information about apertures so I have no intention of repeating what all ready has been done before. So here you will find a couple of links and a list of things you should know or go and find out about. Then some exercises that you should do.
What I recommend you should know about apertures:
- what is depth of field?
- what aperture gives you a shallow depth of field
- what aperture gives you a deep depth of field
- when using a small aperture (large f number) what is happening to the amount of light coming into your lens
- when using a large aperture (small f number) what is happening to the amount of light coming into your lens
- how does depth of field relate to your different focal length lenses? which lens has the greatest depth of field & which one has the least?
- what aperture gives you the sharpest photographs for each of your lenses (if you have zooms this changes with the amount of zoom)
- what does bokeh mean?
- which of your lenses has the most beautiful bokeh?
- in the newspaper press film photographer days the saying to the photographer was "f8 and be there", why do you think they said this?
- what is the "sunny 16 rule" - what does that tell you?
- what is diffraction? can you see it on any of your photographs? what f stop does it start?
- what is the hyperfocal distance? how do you use hyperfocal distance in your photography? how do you calculate hyperfocal distances?
- for advanced photographers: what is the circle of confusion?
Depth of field calculators - lots and lots of good ones
- photograph an object to create subject isolation with a blurry background
- photograph a scene to maximise depth of field so that everything in the photograph is in focus
- align three similar objects on a table in a line so that the objects are at different distances from the camera. Photograph lots and lots of photographs with your camera on a tripod in a fixed position. Try focusing on each of the objects and changing the f stops. Try using different focal length lenses
- use hyperfocal distance to calculate what areas are going to be in focus in a photograph and then take a photograph where all of the objects are in focus
- find some approximate rules for hyperfocal focusing - why might these lead you astray when using them
- photograph a still life with all of the objects in the still life are on the same plane that is perpendicular to the path of the light into the camera. use your sharpest lens and your sharpest aperture