To avoid this, and to gain an understanding of how integral focus can be to your shot, practice is a crucial element. For instance, even with the most professional equipment, manual focus is a critical skill with any level of video production. Here are a few ideas to experiment with and try out:
Within the frame, attention is drawn towards the subject with the sharpest focus. This attention can be changed through the use of focus pulling. For instance, a foreground subject (such as a person) can move away from the frame, with focus instantly thrown back to the background, containing a second subject.
By using a deliberately narrow depth of field, emphasis on a principal subject can be increased. This is down to the contrast between the sharp focus of the principal subject, and the heavily out of focus background (and sometimes a foreground subject is used as well which is also out of focus).
Zoom lens and focus:
Provided the back focus has been correctly adjusted, this is designed to ensure the focal plane is maintained throughout its range. By zooming in without manual focus, images can lose focus and become distorted.
By becoming familiar with these ideas, you can be more artistic and manipulative about what you want the viewer’s attention to be drawn to. As an important but often overlooked aspect to filming, these techniques are most often mastered through practice and experimenting.
To find out more about the different techniques with focus, check out these links: