Focus free lens

A focus free lens is a photographic lens whose focal point is fixed at its hyperfocal distance. Rather than having a method of determining the correct focusing distance and setting the lens to that focal point, a focus free lens relies on depth of field to produce acceptably sharp images. Most cameras with focus free lenses also have a relatively small aperture which increases the depth of field. Cameras with these lenses generally use a viewfinder for composition.

Related Topics:
Photographic lens - Focal point - Hyperfocal distance - Depth of field - Images - Camera - Viewfinder

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The advantage of this design is that it can be produced very inexpensively, more so than automatic or manual systems. The system is also effectively automatic; the photographer need not worry about focusing. It can also be more predicable than automatic systems.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The disadvantages are the fact that lenses of this type produces images that are less sharp than a lens that has been set to the best focal point for a given scene, and they are unable to produce sharp images of objects close to the camera, usually within 8-12 feet. The later limitation makes them unsuitable for portraits, as they cannot fill the frame of an image with a persons face and render it sharp at the same time. This limitation is likely to confuse inexperienced photographers.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Focus free lenses are used in the lowest end and cheapest cameras; disposable and low-end point and shoot. They are usually wide angle with fixed aperture.

Related Topics:
Disposable - Point and shoot - Wide angle - Aperture

~ ~ ~ ~ ~ ~ ~ ~ ~ ~