Theory  of photography 




Camera  :  A camera functions in a very near manner of the eye . The lens corresponds to the crystalline, the diaphragm to the iris, the electronic sensor to the retina .


The big difference is the zoom that can vary the size of the image.  That would correspond in the fact that the eye would have a variable length ( depth ) .


Focal:  The focal length corresponds to the distance between the objective and the electronic sensor.  More the focal is short more the objective transmits a wide image .


We call the focals not corresponding to the human eye  Wide Angle ( that farths the subject and minimise it ) and Telephoto ( that nears the subject and enlarge it  ) .











Focus :  The focus consists to adjust  the distance between the lens and the sensor ( according to the distance of the photographed subject ) in order that picture is sharp .


Diaphragm :  The diaphragm adjust the light that passes by lens . Aperture of diaphragm is determined by a number , more it is small more the diaphragm is opened .


More the diaphragm is closed ( great number ) more the clarity of picture and the depth of field increase .


Speed :  More the speed to take a picture is rapid more the diaphragm has to be opened to determine the quantity of optimal light that reaches the sensor .


These two adjustments are always linked ,  it is necessary to choose if we prefer the speed or diaphragm’s aperture  ( more it is closed best is the result in clarity ) .


White balance :  The color of the light varies according to the source ( daylight  , tungsten lamp , neon tube ) .  The balance serves to obtain the real white for the lighting .


Depth of field :  The depth of field indicates between what distance a nearest object and a farthest object on the photography are well defined ( sharp ) .


Zoom :  The optical zoom and the numerical zoom have not the same result . The optical zoom vary the size of the image but also the relative appearance of elements


( according to the distance ) .  The numerical zoom vary the size of picture but it remains the same , it is also less defined ( pixels of the picture are enlarged ) .


Zoom :  The optical zoom in wide angle position decreases the size of objects ,  separates the different objects and increases the depth of field .


In position telephoto it increases the size of objects ,  brigs together  the different objects and decreases the depth of field.