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Saturday, June 29, 2013

Lesson 2.3: The Shutter... and the Aperture.. and the Sensor...

You've now framed and focussed on your prey... let's talk about the eye...

What one has to realize is that the human eye is constantly framing and focussing on the scene.. and the relevant neurons take the instant signal back to the brain, which processes the scene..

The amazing part is that the brain does not constantly add the information the eye provides over time.. if it did, the images would keep adding up on top of each other and would slowly become an all white blur.. the brain somehow separates images over time and we therefore see an unchanging scene..

Its a little complicated but if you think about it, it is quite amazing...

The SLR camera on the other hand has no such feature.. if it sees light from the same image, no matter how dark, for long enough, it will fade into white...

A video camera on the other hand does not have this problem, exactly because it knows that every x milli-seconds it is taking a new photo...

Before going ahead, refer to the section on the Lens as an adder of light.

So some basics on the hardware:
1. The shutter decides the volume of light that can get in.  The longer it is open, the more volume of light that gets in.  This is determined by the shutter speed.
2. The aperture/lens-system is like the iris/lens.  The wider it is open and the bigger the lens, the more orders of light that can get in.  This is the f-number.
2. The sensor is like the retina.  The more sensitive it is, the better it can resolve what the aperture let in.  This is the ISO rating.

The perfect picture is simply a combination of how much light you let in, how accurately your aperture/lens system can replicate the image, and how well your sensor can resolve what was let in.

You see something with your eyes.  You feel something.  Your camera tries to capture it and show it to someone.  The other person feels something.

Communication.  That is the basic purpose of photography.

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