Working With Depth Of Field
The depth of field is the area in the shot where all the items in it look sharp. You can say the depth of field “decides” what is going to be sharp in the picture and what is not and by that creating depth in the picture.
The two types of depth of field
There are two types of depth in image: shallow depth and deep depth.
Shallow depth is a field in the shot where the focus area is very small. We usually use it to direct the viewer’s attention to something specific in the frame. You might also see it a lot in interviews. The DSLR cameras became very famous because of their ability to create a shallow depth of field very easily. Anyway, what you need to remember is that the closer you are to the photographed object, the shallower the depth of field is going to be.
The second type is Deep depth which means that the entire frame from background to foreground is as sharp as possible.
The three factors that contribute to the depth of field
Aperture -This mechanism is in charge of the size of the lens opening that determines the amount of light entering the lens and also the angle of light rays that are hitting it. Aperture is measured in f/stops, for example, f/2 or f/16. F/2, For example, represents an aperture diameter that is 1/2 the focal length of the lens. Therefor, f/2 will be bigger than f/16.
A larger opening will decree the depth of field. If your camera has an internal neutral density (ND) filter you can dial this in.
Focal length – The longer the focal length of your lens is, the shallower the depth of field will be. In other words, the more you magnified your object the less depth of field you’ll have.
The 3rd factor is the distance of the object from the camera– The closer you are to the filmed object, the shallower the depth of focus will be, the farther the object is- the greater the depth will be.
There are many tables that can help you do calculations needed, but there are not always accurate and sometimes missing the new cameras and lenses out there. I recommend playing with those 3 factors until you’ll have complete control and understanding on them. If you don’t have time for playing, there are many apps that can help you to calculate the depth of field. A good one is called pCAM FILM + DIGITAL PRO – Thin Man Inc. This app not only does great calculations with a depth of field, but it also calculate exposure, running times and more. Another good app is Toland ASC Digital Assistant – Chemical Wedding which also does a lot more than just calculating depth of field
Shooting with depth of field
Using this tool needs to be considered while doing the shooting breakdown. Let’s say you are shooting a scene with a long shot, a medium shot, and a close-up, you may need to increase the light in the medium shot in order to get the depth of field you want or even to change lens.
The depth of field is a great way to make a good picture, but also good to manipulate the viewer’s emotions and concentration. Don’t use it just for the sake of using it. On the set while looking at the picture on the monitor, you should always ask yourself, is it what I want? How does it serve the theme of the scene and even the premise of the film (among other question we will learn later on in the blog)? Using this tool right will make your film look more professional and interesting.