Depth of field and aperture selection question.

[s_erez]

Hi,
I am relatively new to digital photography and I have a question related to aperture selection.
I am familiar with the theory behind the depth of field, the larger the aperture the more of a shallow depth of field and vice verse.
This is very simple to understand, however my question is how do you know which aperture to use for a specific situation?
I know about the depth of field button on the camera, but I could never see what my picture will come out when I used it.
Any techniques or tricks I could learn and use?
Thanks,
Erez.

[17-40F4L]

practice, experience

[cdifoto]

Originally Posted by s_erez

Hi,
I am relatively new to digital photography and I have a question related to aperture selection.
I am familiar with the theory behind the depth of field, the larger the aperture the more of a shallow depth of field and vice verse.
This is very simple to understand, however my question is how do you know which aperture to use for a specific situation?
I know about the depth of field button on the camera, but I could never see what my picture will come out when I used it.
Any techniques or tricks I could learn and use?
Thanks,
Erez.

Just kinda guesstimate really. Shoot a lot of situations with various focal lengths and apertures and see what it gives you. After awhile it becomes second nature.

That said, sometimes you're stuck with an aperture you don't really want to use because of the extremely narrow depth of field but need to suck in all the light you can get...

[kevin_c]

Typically...

For landscapes, or any shot you want everything (or nearly everything) to appear in-focus you need to select a small aperture (f/11 - f/16 for instance)

For portrait's or any shot you want to isolate the subject and 'blur' the background you would select a large (f/4 - f/1.2 aperture)

Of course this is all 'typical' situations - you may want to use limited DOF on a landscape for effect etc. and if taking a group shot at a party you would use a smaller aperture to ensure everyone is in focus...

It does all come down to experience really.

[PhotosGuy]

It does all come down to experience really.

True. At a distance, DOF extends 1/3 toward you & 2/3 away from the point of focus. In very close-ups, DOF extends 1/2 toward you & 1/2 away from the point of focus.
So if you're 10 feet from a subject and have a DOF of 3 feet, then everything from a distance of 9 feet to 12 feet will be inside the DOF
You could actually focus just short of infinity & get more DOField toward you. It used to be easier when all lenses had focusing marks on them.

Or you could try DOF tables to get a better idea of what's happening:
Depth-of-field

See the DOF calculator at the bottom.