1)viewfinder-the viewfinder is where the photographer looks to see what he/she is taking a photo of.
2)parralax-is an apparent displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.
3)lens-a piece of glass used to focus and zoom
4)pentaprism-A pentaprism is a five-sided reflecting prism used to deviate a beam of light by 90°.
aperture-an opening that limits the amount of light let in


shutter-a mechanical device for opening and closing the aperture

exposure-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.

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 apereture, as indicated by an f number

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