The Camera and Eye.

Some knowledge of the eye will give a better understanding of the camera.

The Eye.

• Basically the human eye is an orb with a dark interior. To enable the eye to see, reflected lights must enter the eye. At the back of the eye is the Retina. The Retina is light sensitive and contains different types of cells.  One type of cells can distinguish shapes and another colours.  The shapes and colours make an image which is then transferred from the Retina to the brain via the optic nerves. This make you 'SEE'.

• Lights enter the eye through an opening, the Cornea. Behind the Cornea there is a transparent lens. The ancillary muscles around the lens flex and relax changing the lens shape causing the focal length to vary.  Different focal lengths bring different objects in different distance into focus.  This way you see every object clearly whether they are near or far.

• In between the Cornea and the lens there is a circular flap with a round opening in the center. The flap is the Iris and the opening, the Pupil. The Iris is the coloured part of your eye. This is the reason why you have brown eyes and your Mat Salleh (Westerners) friends are blue. The Pupil  always look black because it shows the dark interior. The Pupil reacts instantly to lights. When the outside is very bright, the Iris opens up and this make the Pupil (the hole) very small preventing light from entering. So when it is dark outside, the Iris will close,  the Pupil dilates to allow more lights to enter.

The Camera

1. The camera is an electro-mechanical device that imitates the human eye.

2. The camera has a black chamber.  The dark interior prevents admitted lights from escaping.

2. The camera lens mount (the hole in the front of the camera) is the Cornea of the eye. This is where directed lights enter the camera. If you use a DSLR, (digital single-lens reflex) the lens mount are made in such a way that it can only receive proprietary lenses.  In other words the camera and the lens mount must be compatible in order to connect.   This opening is a very sensitive part of the camera.  It houses the electrical connections between the camera body and the lens. The connections are usually plated in gold. You can see them as little golden dots located on the rim of the mount. The corresponding connectors are located at the back of your lens. Once properly connected, the camera is able to send electrical impulses telling  the lens what to do.e.g. shorten or lengthen the barrel (focusing).

3. Unlike the human eye, the camera lens is located in front of the Cornea (lens mount). The lens is actually a collection of optical glasses housed in a cylindrical barrel. The lens barrel is usually inscribed with the focal length (mm) of the lens e.g. 50mm or 18-55mm. Do not worry about these numbers.  Explanation later.

4. At the back of the lens there is a series of blades that form a diaphragm. This is equivalent to the Iris in the human eye.  The diaphragm size control the size of the hole formed in the center.  This hole is the same as the Pupil in the human eye.  In Photography this hole is the Aperture.  The aperture setting is based on a standard. (more of the Aperture later).

5. The sensor (Retina) of the camera is located inside and back of the camera. Like the retina it captures external reflected lights and then formed the image before storing it in the memory card. Different camera models and brands use different type (proprietory) of sensors e.g CMOS (Canon),   Of course it goes without saying the more expensive camera utilises a bigger and better sensor.

6. There is an additional mechanism in a camera called the Shutter.   It functions exactly like the window  shutter slates.  In a camera the slates are place closed and in front of the sensor.  When you clicked on the shutter release button  to take a picture, the slates open allowing the reflected lights to reach the sensor.  In a camera you can control how long the shutter remains open.  This is the shutter speed and it is noted in seconds or a fraction of it (sec) e.g. 1/30, 1/60 etc.

Another important component in a digital camera is the microprocessor.  The Canon 40D utilises the DIGIC III image processor (more of this later).  Now that you have some insight into the camera you will appreciate it as a marvelous piece of technology!