When shooting video on a DSLR how can you keep the shot focused accurately without using auto-focus?

Answer 1

When we compare our home videos to the content we see every day on Broadcast Television, it becomes fairly obvious that most broadcasters do a pretty good job of production.

In big television productions and movie productions, the camera operator is often assisted by a focus puller. His job, as the name implies, is to pull the focus controls to reach adjust the optical focus during filming. It's a skilled job and one that's important enough to dedicate an operator to doing. The focus puller will frequently have the opportunity to rehearse shots, to mark focus points on the focus rack and for every shot, work to his own script so that focus stays sharp throughout the shot.

The average one man production team filming the family on a day out doesn't have the luxury of rehearsing shots, nor will most subjects be working to a script or moving to preset points with a focus mark already set. However, a few minutes before hitting the record button can make a big difference. Knowing the focus points of various landmarks in the shot will assist in moving the focus from one to another. If you can mount the camera on a tripod, you will have a hand spare to make the adjustments and you have the assurance that the shot won't drift as you change focus.

As a final thought. most DSLRs that use auto-focus don't have viewfinders designed for manual focusing. Some of the more expensive system cameras have an option to change the viewfinder screen to include a focusing aid similar to the older film based SLRs. If you are serious about getting focus right, it's worth investigation the options for your own camera.