Playing with DoF... still learning

[Kris]

After Glen's tutorial during the week, I thought I'd have a play with this today in A mode

Can someone clarify, to increase the DoF (that is have more in focus for say a landscape) you have a higher F stop value (F22 on my Kit lens)

To decrease the DoF (to say focus on a boat in the harbour and leave the rest out of focus) you use a smaller F stop value (F4.5 on my Kit lens)

Is that correct?

In situations where I want to ensure everything is focus, would I choose somewhere between? In this instance, to focus on the city skyline and the keys in my hand? I used F16 which I think has managed to focus everything?


Here are some pictures

[Greg B]

Hi Kris

DoF is effected by two things - the aperture (F-stop) and the distance from the camera to the focus point.

If the focus point is far away, the DoF is greater than it would be if the focus point is close up.

You are correct, a smaller aperture (which is a larger number f stop) gives a greater depth of field than a large aperture. When you look through the viewfinder, the aperture is as big as it can be (wide open), - the depth of field preview button closes the aperture down to what it will be when you take the photo so you can see the DoF that you will get (of course, this will make what you see in the viewfinder darker, so it can be a bit difficult to tell).

cheers

[Kris]

Excellent, I understand fully now