"Point and shoot" digital cameras have become an important part of
lives of anyone and everyone who wants to take pictures and have made
taking pictures as easy as point and shoot. For most people they are
good enough and at most times they are good enough. Besides others,
one down side has been that people don't need to know some very basic
stuff about photography. One of them is about the way we can control
"depth of field" in a photograph.
We need to have a short/small depth of field while taking pictures
like portraits, as we are focusing on one subject and we want
everything else to be blurred so that the viewers attention only goes
on the object of interest. We need a long or deep depth of field while
taking pictures like landscapes as we want all objects, near and far,
to be in focus.
Depth of field/focus is controlled by the aperture size of the
shutter. It is represented by a number written after the letter "f" eg
f/5.6 , f/29. The smaller the "f" value, the bigger the apertures size
and vice versa. A large aperture number (eg f/29) means a very small
aperture and that acts like a "pin hole" and that makes focusing not
that important and all objects, near or far, are in focus. A small
number (eg f /5.6) means a large aperture and precise focusing becomes
very important.
While taking pictures two very important factors which control the
light exposure are the shutter speed and the aperture size. If the
aperture is large, we need to shutter to close quickly to let a
certain amount of light to pass through. If we make the aperture
small, we need to have the shutter open for a longer time for the same
amount of light to pass through.
In the two photos attached, I have focused on the red cap of the
bottle as I took the pictures. The two pictures have however, been
taken with different aperture settings and corresponding shutter speed
changes. You can read the settings in the bottom left corners of the
photos. You can make out that in the first picture the depth of field
is pretty good and almost all seems to be in focus unlike in the
second photo.
Sarbjit Singh
