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How Cameras Work - The SLR camera in a nutshell!
-Compiled by Dr.Umesh Pathak
The basic principle of capturing light to make a permanent image has not changed for
hundreds of years. Artists from centuries ago used a simple, one element lens to throw a
reversed and flipped image onto a piece of paper enabling them to trace the outline of a
subject that they wished to paint.
This is how some of the oldest paintings are so incredibly accurate with regards to
composition and proportions. Did you ever paint people with excessively large hands or
small heads at school? It is difficult to judge, but when using the above methods, you cannot
go wrong.
The SLR camera is no different. The light passing through the lens is flipped and reversed in
the same way and firstly projected onto the focussing screen via the mirror. This enables
you to see what will be recorded and make adjustments to the focussing and composition.
How Cameras Work - Fig. 1
When you take the shot, the mirror is lifted, the shutter opened and the light hits the sensor
at the back of the camera.
The distance from the rear of the lens to the focussing screen (when bounced from the
mirror) is exactly the same as the distance from the lens to the sensor. This is necessary to
be able to "shoot what you see".
Quite simply, if you focus, compose and expose your subject well, that is all you need for a
good shot! In a nutshell, most of the features of modern Digital SLR's could be redundant;
they are there to increase speed, efficiency and to satisfy our desire for gadgetry,
technology and sometimes, laziness.
As proof, take your camera outside and try this. If you have a tripod, use it. Set the camera
to fully manual including setting the lens to manual focus. Line up the shot, focus carefully,
use the camera's built in light meter (the led bar in the bottom of the viewfinder) to set the
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shutter speed and aperture correctly and just take the shot. Just adjust the aperture and
shutter speed until the bar in in the center. That means the exposure is correct.
Now switch the camera to Program mode or fully auto including focussing. Take another shot and
have a look at them both. Apart from varying depth of field due to aperture fluctuations, the images
should be practically identical. Many people, including myself as a youngster, mistakenly think that
"Fully Auto" means better pictures.
My point is that it is not important to get caught up with all the latest updates, upgrades and
features when what you should really be doing is improving your "eye" and the basic principles of
how cameras work. Your ability to see a great shot, capture it well and process it to perfection are
more important than all the technical jargon that is widespread nowadays.
One of the most famous photographers of our time, who sadly died in 2004, was Henri Cartier-
Bresson. He mainly used a simple 35mm camera with a standard 50mm lens and very little else.
No filters, no matrix metering, no 45-point autofocus and no Photoshopping, just a keen eye.
Of course, in the real world, we all crave knowledge and understanding. It is sometimes necessary
to know how the modern cameras function and how to put their features to best use, especially in a
more professional capacity when time and perfection are of the essence and that is where this book
comes in.
In my opinion, it doesn't matter how an image was created, if it looks good, it looks good but
everyone is different and has different tastes, styles and techniques, which brings me back to my
original point. Learn the functions and features of your equipment, find what "works for you" and
get out and enjoy yourself!
How Cameras Work - Just for your information, the settings that I personally use 95% of the time
are these:
Focussing - Auto, centre-point only, one shot (Servo sometimes for sports). See Chapter 11.
Metering - Evaluative. I.e. an average of the whole scene. I use exposure lock on many
occasions to make any necessary adjustments. See Chapter 4.
Mode - Av/Aperture Priority, Tv/Shutter Priority or Manual. For much of the work I do, I
would rather have control over the depth of field than the shutter speed. If I need a fast
speed, I simply whack open the aperture to the largest to give the fastest possible shutter
speed although on ocassion, it is good to be in control of the shutter. See Chapter 10.
ISO - 100 to 500, nowadays the difference is barely noticeable. Have used up to 1600 on
occasion.
These chop and change depending on what and where I shoot but are the general settings I tend to
use.
Experiment with different set ups to find what is good for you and your style of photography, all the
practising "sinks in" over time and you will have a much better understanding of your equipment
and how it works.
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