The following lesson was created by Vimeo for its Vimeo Video School . It’s used here with permission. Look for a new lesson each week.
When I was a kid, our family only had one camera. It was a 35mm point-and-shoot with autofocus. Today we have all sorts of cameras, from mobile phones to camcorders to DSLRs to point and shoots… the list goes on! But there’s one thing all these devices have in common: Focus.
Focusing is adjusting the lens of your camera until you can see your subject in maximum detail. Professionals like to use the term “tack sharp” to describe when the subject of an image is in perfect focus. An unintentionally out-of-focus shot can be distracting to the viewer, and can remove your audience from your video or film. However, intentionally leaving areas out-of-focus can also be used as a storytelling device, bringing the audience’s attention to something specific, or obscuring the villain standing behind your main character.
When focusing, the lens element inside your camera moves closer or further from the image sensor depending on which direction you rotate the focus ring. Once the light is properly converging on the image sensor, you will have a focused image.
Shifting focus from a nearby object to a faraway object within the same shot is called “racking focus” and is commonly used to bring the audience’s attention from one subject to another. Professionals and amateurs alike do this by using something called a follow focus, and you can build one yourself  to make racking focus much easier! Here’s a quick example of how racking the focus can add a little bit of drama and tell a story, all within one shot:
Most cameras today have autofocus built in, and you might be wondering why we don’t just leave it on all the time. Autofocus can be pretty good at guessing what subject you want in focus, but it may not always get it right. Lots of movement within the frame or moving the camera itself can cause a distracting “pulsing” effect as the autofocus decides what subject should be in focus.
Manual focus is the setting we need to assure all our shots are tack sharp on the subjects we want. Check out the following video showing you how to manually focus on a couple of common camera types:
Here’s the breakdown of how you can manually focus on different camera types:
- DSLR: Find the MF(manual focus) switch on the lens or front of your camera body, and use the focus or zoom assist button to get the image sharp by turning the focus ring.
- Camcorder: Set your focus to “M” near the camera lens, and use the focus assist to establish focus. Some cameras don’t have focus assist, so check your user manual first.
- Point & Shoot: While not exactly manual focus, you can lock your autofocus before taking your shot by pressing the shutter button halfway down, and then pressing the shutter all the way down to start recording.
- Touchscreen Smartphone: Tap the screen where you want to focus (depending on your phone, this may adjust the exposure too! )
One rule of thumb to focus on a video camera is to establish your shot, zoom into your subject as much as possible, focus on your subject, and zoom back out and reestablish your shot. Your subject will remain in focus as long as it’s stationary. You can try this technique with DSLR cameras, however the zoom on some lenses can throw off your focus. Most video-capable DSLRs have a “focus assist” button that will digitally zoom on a subject to help establish focus. Explore your user manual or post in our friendly Cameras and Editing forum  if you have trouble focusing with your camera.