In photography, the term “Focus” means the point of maximum sharpness in the photo. Normally, the focus will be made either manually or automatically, so that the main subject of the picture is as crisp and clear as possible.
Flowers, botanical garden, Montreal
In the above image, the focus is made on the center of the central flower, the main center of attraction in the image then.
Focus Range
Every camera lens has a focus adjustment range , ranging between a certain minimum distance and infinity, denoted by the symbol ∞.
Old style lens barrel with focus scale and mark.
Camera focused on the main subject
For example, if the photo is a travel portrait of one person, the focus will be made on that person rather than an object in his/her environment. Some very sophisticated cameras are even able to detect the subject’s eyes and to keep them in focus in real time!
Or if the photo is of a bottle of wine on a table, in a delightful setting; focus will be made on the bottle, not the landscape behind. And preferably, on the label of the bottle, and not on it’s cap. Simple logic, no?
So, almost without exception, a sine qua non characteristics for a good photo of a subject, is that the main subject is in focus and not blurred.
Autofocus
The photographer will use either the camera’s autofocus system, or if the option is available, she may prefer to focus manually to have more control and more precision in setting the focus on a specific area of the image. It can also happen that the autofocus does not work for a given subject. For example, you want to photograph a subject that’s behind a grid or a fence or make the photo through a window. In such a situation, it often happens that the camera focuses on the fence or window, and not on the actual subject. In such a case, a capacity for manual focus will be extremely useful.
An inaccurate focus point is also one of the best ways, with camera shake, to miss a photo!
Here are two examples of failed focusing:
Click to enlarge: Out of focus balloon in flight. Image © Charles Martel 2002
Click to enlarge: Yellow bird out of focus. Image © Charles Martel 2012
Artistic Soft Focus
However, it may happen that for artistic reasons, a photographic image presents a soft or fuzzy main subject. But this is relatively unusual. And it is usually pretty obvious, looking at the image, that the blur is a deliberate photographer’s choice. But not always! 🙂
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© Charles Martel 2015