The collector/field lenses act to collect light from the light source and focus it at the plane of the condenser diaphragm.

The cornea and lens act together as a compound lens to project an inverted image onto the retina.

Gravitational lenses act equally on all kinds of electromagnetic radiation, not just visible light.

The lens acts to concentrate light; all the light that falls on its relatively broad width is brought into the compass of a narrow spot.

All lenses are multiplied by a 1.33x crop factor, hence a 28mm lens will act approximately like a 35mm when mounted to the M8.

Once myopia is corrected, the crystalline lens acts its age, with nothing to compensate for it.

When a cylindrical lens acts as a magnifier, it magnifies only in one direction.

A lens on a flexible shaft acts as an eye.

Because the lens acts as a relatively immobile membrane at night, it is not difficult to calculate the level of permeability required.

The two lenses act as a telescope producing a flat phase front of a Gaussian beam on a virtual end mirror.