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 1

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.

Answer 2

I agree aperture is the one of the biggest settings that will (next to exposure) change the look and feel of your photos. A lower aperture number (f4.0) for example means that your aperture is open wide.

This causes objects to be blurred that are outside of the focal area. The smaller the number the less focal range you have.

Reducing the aperture setting to a higher number reduces f22 for example will increase your depth of field and make the opening smaller there by reducing the amount of light allowed into your camera. This will make your focal range wider.

If you are in bright light and want to have a short depth of field (f3.5, f2.8, etc), but want a longer shutter speed you can use things like a polorizer (it will reduce aperture 2 f-stops) or a neutral density filter (they range from ND2 to ND16, the number indicates the number of f-stops in light reduction that it will do) without changing your Focal Range or depth of field.

Hope that helps, Damien