Term 4 Session 4 SLR's and Digicams, "F" numbers, Depth of field, Exposure Compensation

(UPDATE Aug 2012 - I have removed images that won't display correctly but will leave the text here as reference)
Much of my additional information comes
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site called "Wikipedia" which is at http://en.wikipedia.org/wiki/Main_Page
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10 million articles have been written collaboratively by volunteers
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Launched in 2001 by Jimmy Wales and Larry Sanger,^[7]it is currently the largest and most popular^[1] general reference work on the Internet.^[8][9][10]



Parallax Error
Parallax is an apparent displacement or
difference of orientation 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






Digital single-lens reflex camera.

http://en.wikipedia.org/wiki/Digital_single-lens_reflex_camera


A digital
single-lens reflex camera
(digital SLR or DSLR) is a digital camera that uses

a mechanical mirror system and pentaprism to direct light from the lens to an optical

viewfinder on the back of the camera.







Compact
digital still camera
http://en.wikipedia.org/wiki/Digital_Camera

A digital camera
(or digicam for short) is a camera
that takes video or still

photographs, or both, digitally
by recording images via an electronic image sensor.

Front and back of a Canon PowerShot A95.

Many compact digital still
cameras can record sound and moving video
as well as still

photographs. In the Western market, digital
cameras outsell their 35 mm
film counterparts.^[1]

F-number
http://en.wikipedia.org/wiki/F_stop
In optics, the f-number

(sometimes called focal
ratio, f-ratio, or relative aperture^[1]) of an optical system expresses


the diameter of the entrance pupil in terms of the focal length of the lens; in simpler terms,

the f-number is the focal length divided by the "effective" aperture
diameter.

It is a dimensionless
number that is
a quantitative measure of lens speed,

an important concept in photography.






Depth of field
http://en.wikipedia.org/wiki/Depth_of_Field
In optics, particularly as it relates

to film and photography, the depth of field (DOF) is the portion of a scene
that appears sharp

in the image. Although a lens can precisely focus at only one
distance, the decrease in

sharpness is gradual on either side of the focused distance, so that
within the DOF, the

unsharpness is imperceptible under normal viewing conditions.




NB.These pictures are also courtesy of Wikipedia
F22 = Very deep field


F2.8 Very shallow field


At f/32,
the background is distracting.


At f/5.6,
the flowers are isolated from the background.




Metering mode
http://en.wikipedia.org/wiki/Metering_mode
In photography,

the metering
mode refers to
the way in which a
camera determines the exposure.



Exposure compensation


http://en.wikipedia.org/wiki/Exposure_compensation


Exposure compensation
is a technique for adjusting the exposure indicated by a photographic

exposure
meter, in
consideration of factors that may cause the indicated exposure to
result in

a less-than-optimal image. Factors considered may include unusual
lighting distribution,

variations within a camera system, filters, non-standard processing,

or intended underexposure or overexposure. Cinematographers may also
apply exposure

compensation for changes in shutter
angle or film speed, among other factors.