When should I use which aperture settings?

Question

I just bought a new Canon EOS 60D and working to choose a great lens. I have used DSLR before but never seriously. I have few questions on aperture which might be obvious to many but very helpful to me and possibly to few other who are new. I'll mainly be using aperture priority.

My question is: what should be common value of aperture in following situations? I understand correct value is scene-specific but common values will help.

(Let's assume it's daytime)

1. On streets everyday
2. Indoor.. .Like a living room
3. Park
4. Landscapes
5. In a bar
6. Cityscape

and how will that differ compared to night.

Answer

There is no 'correct' aperture, even for a specific scene. It doesn't just change your exposure, it changes the depth of field of your photograph. Its a creative portion of your composition.

In dimly lit areas like indoors, in a bar, etc - you probably want lower f/stop numbers 1.4-2.8 (bigger apertures) - but only if you want correspondingly shallower depth of field.

Outside in bright light, you may want larger fstop numbers (8+) because you have the light to use it, but only if you want deeper depth of field.

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