Depth of Field Question

[MiraLiz]

Hi, I'm pretty new to filmmaking and I'm having trouble grasping the concept of depth of field. I've looked at several sites and tutorials on the internet, but I still can't seem to get it. If someone could give me a little overview of depth of field, and how to achieve a shallow depth of field, that would be great. I don't know if this is relevant, but the camera I'm using is a Canon GL2.

Thank you!

 

[David Mullen ASC]

True Depth of Field is the range of focus in which an object looks "acceptably" sharp. If you have a lot of depth of field -- i.e. deep focus -- then a wider range of distance will fall into focus.

But there is also the issue of the illusion of deep or shallow focus, which is more about how much the background behind the subject looks sharp or not. Wide-angle lens tend to give the illusion of deep focus because they make the background recede in size faster, so you see more (larger field of view) but the details are smaller in size, so you can't tell if they are soft or not.

Telephoto lenses have the opposite effect -- since they see a narrow amount of background but enlarge it in size, you can tell that details back there are out-of-focus compared to the subject in the foreground.

But basically the short answer is: shoot at the widest lens aperture possible (use ND filters if necessary to allow this, and make sure you are in manual mode so that Gain doesn't kick in to compensate for being wide-open). Use the most telephoto end of the zoom as possible. Shoot as close as possible. Separate the subject and the background as much as possible.