Description: A lens which is specially designed to control the effects of chromatic distortion or aberration (a defect of optical lenses ... of which one is typically a concave and another is convex.

The centre of the lens is called the optical centre C. In a ray diagram, a converging lens is drawn as a vertical line with outward facing arrows to indicate the shape of the lens. Point the lens ...

These are shutter speed, aperture and ISO. Even if you've never changed the f-stop on your lens or through your camera, you've probably noticed this setting at some point. Click above to understand ...