This adorable picture of my precious baby is a perfect example for the photographic concept of depth of field, which is a fancy way of explaining why just the baby is in focus.  Selective focus makes the subject of your picture pop. The background and foreground both are softly out of focus so a viewer’s eyes instantly dart to the subject of the picture, regardless of what it is.   Brushing aside the obvious fact that my little girl is too cute, the depth of field in this image is one of the technical reasons why it is an outstanding picture.

In professional videography, getting the background out of focus when taking pictures of people (or any subject matter) is highly desirable, so has developed into an art unto itself.

There are a variety of ways you can achieve an out-of-focus background.  You can do it while you are shooting the video, (easier way) or you can fake it later in the edit room.

One thing I find funny is that a lot of TV stations will stick an out-of-focus still picture two inches behind someone’s head because they do not have the room to do it the right way.

Let’s first describe how to achieve this effect while taking the video.

An out of focus background is not dependent on what kind of camera you have.

Here are the things that matter:

• Your lens settings
• Distance between the camera and the subject
• Distance between subject and background
• Amount of light

Basically what you need to do is manipulate the depth of field of your shot. Just like the baby picture above, you want a SHALLOW depth of field.  In other words you want everything BUT the subject matter out of focus.

If you would like to read more about the basic concept of depth-of-field, you can read some background information by clicking here. Basically depth-of-field boils down to how much of your shot is in focus from front to back.

To get a shallow depth of field, shoot using a long lens in fairly low light.  If your video camera has a zoom lens, then it is in the “long” position (telephoto) when it is zoomed all the way IN.  A long lens automatically gives you shallow depth of field.  Low light also gives you a shallow d-o-f.  So you combine the two techniques for the most dramatic results.

Of course you can’t go TOO low with your light or the picture will not look good. But soft, diffused light, about the quantity you’d want in a fairly well-lit living room will produce the results I am talking about.

On top of this, select a location where can have about five to ten feet of space between your subject and the background.  With a shallow depth of field, this much distance will ensure that the background will be out of focus naturally.  With an extremely shallow depth of field, you could get away with MUCH LESS space than that.  The blurry background on the baby picture is just a few inches.

In order to use your long lens, you will need a bit of room.  It’s best to have the camera back about ten feet away from the subject.  Then you have plenty of room to zoom in as much as possible.  The more you zoom in, the more shallow your depth of field becomes.

Whenever you are using your long lens zoomed in, make sure and use a tripod, otherwise the shot will look shaky.  One of the characteristics of a long lens is that camera shake is magnified.  Tripods are essential when using a telephoto lens.

In short, as the videographer, you need to create the proper circumstances to make the background appear out of focus.

METHOD TWO:  DO IT IN POST PRODUCTION

If you want to blur the background while EDITING, it takes a video program that has at least 2 lines of video. This is considered an advanced editing technique.  First, here is some quick background on video editing basics to make sure you understand what I am about to talk about.

Here is an example of Windows Movie Maker. The timeline is the bottom portion of the screen. WMM is a limited program and you could not do this technique in WMM.

When you are editing video, the process is to stack video and audio elements onto lines inside what is called a timeline.  The more complex the program, the more lines of video and audio you have available to you.  The line on the top shows.  When you see multiple images on the video screen, for example shots of credit cards, or words, or logos, those are small video images stacked on top of the shot of the person speaking.

Anyway….to blur the background behind people takes two lines of video.  If a video editing program has the capacity to blur a shot, it will blur the ENTIRE shot.  This is true for all editing software, no matter how sophisticated.  (The blur feature on whatever program you use will probably be found under filters.) The trick is to use two lines of video to make one part of the image blurry and the other part not blurry.

Take the shot of your person and duplicate it on top of itself.  Take the video on line 2 and cut out the people using a matte filter.   Then, turn your attention to the video on line 1.  Add a filter to this bottom shot that takes it completely out of focus.  The video on line 2 is still in focus, and that is the people. Since you have cut away some of the shot with a matte, whatever you cut away shows up from the blurry video on line 1.  To make this look natural, it takes some tweaking to soften the edges.  The better you cut out your people, the more natural it will look.

WHICH ONE IS FOR YOU?

Now you have all the information you need to compare the two techniques for yourself.  If you want the back ground out of focus in your shot, which way is more practical?  It’s up to you.

THERE’S A THIRD WAY TOO

If you shoot your people in front of a green screen, you can cut then out precisely and put any background behind them you want.  Green screen adds a whole new dimension to the process.  Read more on green screen at this post.

Thanks for reading Video Production Tips

Lorraine Grula

Internet Video Gal