Lens

Chapter  Fourteen

A photography lens (also known as objective lens or photography objective ) is an optical lens or assembly of lens used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.

Exposure

Chapter Thirteen

Correct (exposure) depends on three things i.e. *Aperture, Shutter speed and ISO* (Film speed). In photography, exposure is the total amount of light allowed to fall on the photographic medium (Photographic film or image sensor) during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value* (EV)* and scene luminance over a specified area.

ISO

Chapter  Twelve

*ISO* also called *(ASA/FILM)* speed. *ISO* determines how fast the film or *(CCD)* sensor reacts to light. The slower the speed, the slower the reaction to light so longer shutter are required which, in turn, will affect the aperture you can use.

Aperture and Shutter Speed

Chapter Eleven

*Aperture* and *shutter speed* work together. Aperture  is measured in( f-stops) and shutter speed in seconds or fractions of a second because both are calibrated so the each setting changes by a factor of two newer *(digital SLRs)* break that rule they are to some extent, interchangeable in controlling the amount of light that makes up the photo exposure.

Shutter Speed

Chapter Ten 

The camera shutter control the amount or length of time, which allow the light to reach the film or CCD. Adjustment of the speed (often expressed either as fraction of seconds or as an angle, with mechanical shutters) of the shutter to control the amount of time during which the imaging is exposed to light for each exposure. Shutter speed may be used to control the amount of light striking the image plane, “faster”  shutter speed (that is , those of shutter duration) decrease both the amount of light and the amount of image blurring from motion of the subject and/or camera.