The Camera.

Aperture-a usually circular and often variable opening in an optical instrument or device that controls the quantity of radiation entering or leaving it

Shutter-a mechanical device for opening and closing the aperture of a camera lens to expose film or the like.

Exposure-the act of presenting a photosensitive surface to rays of light.The total amount of light received by a photosensitive surface or an area of such a surface, expressed as the product of the degree of illumination and the period of illumination. The image resulting from the effects of light rays on a photosensitive surface.

Depth of field-the range of distances along the axis of an optical instrument, usually a camera lens, through which an object will produce a relatively distinct image.

F-stop-the setting of an adjustable lens aperture, as indicated by an f number.

Focal length-the distance from a focal point of a lens or mirror to the corresponding principal plane.

My Words

Visible Spectrum-the range of wavelengths of electromagnetic radiation that is normally visible, from 380 to 760 nm.

 Electromagnetic Spectrum-the entire spectrum, considered as a continuum, of all kinds of electric, magnetic, and visible radiation, from gamma rays having a wavelength of 0.001 angstrom to long waves having a wavelength of more than 1 million km.

Etymology-the study of historical linguistic change, esp. as manifested in individual words.

Iris-the contractile, circular diaphragm forming the colored portion of the eye and containing a circular opening, the pupil, in its center.