Shooting through a filter or an optical accessory can produce a variety of visual effects. Some are used for image enhancement, others as visual gimmicks. They may be clipped onto the front of the lens, or mounted in an internal filter-wheel within the camera head, ready for instant selection.
Under very strong sunlight you normally have to stop the lens well down, to prevent over-exposure. But small lens apertures are not always desirable –
• Because camera lenses give better image quality at around f/5.6 to f/8.
• Because the resulting depth of field may be greater than you want.
By introducing a gray-tinted neutral-density (ND) filter which will cut down the light without affecting ...