Saturday, December 29, 2007

LESSON #1 -- How Cameras Work


If you want to know how your camera works, READ THE MANUAL!

That's great advice that each of us should use to learn about our own specific camera model. But, what I want to cover in this lesson is how cameras work, IN GENERAL. If you read the manual but don't really know how a camera works, it might be a little confusing. In fact, it might be a lot confusing.

In plain terms, light passes through a lens and is focused on something that records the effect of the light. That "something" could be traditional photographic film or it could be a high-tech digital sensor. On its way to the sensor, the light will pass through an aperture which is just an adjustable-sized hole in the lens. If the aperture is large, then there will be a lot of light pass through for a given amount of time. If the aperture is small, less light will pass through in the same amount of time. Remember APERTURE. It's the hole that the light passes through. Its size is important in a lot of things we will learn about.

Then there is the SHUTTER. The shutter is the little curtain that opens and closes at a very specific rate of speed to allow the light to get through to the sensor. SHUTTER SPEED is the term we use to indicate how long the shutter is open.

So, let's review: Light travels through a lens to get focused on a sensor material. Along the way it passes through an aperture and a shutter. The size of the aperture is adjustable and the time that the shutter is open can be changed.

When you press the button on top of your camera, the shutter opens and the sensor is EXPOSED to the light. When we talk about EXPOSURE we are talking about the amount of light that reaches the sensor. If there is enough light to make a good photograph then we would say we have a good exposure. If too much light hits the sensor then we have OVEREXPOSED our photo and it will be too light. Likewise if too little light gets through, the photo will be dark and we call it UNDER EXPOSED.

So how much light does it take to get a good exposure? That depends on how sensitive your sensor or film is. Back when we all used film we bought 100 speed, 200 speed, 400, 800 or even 1600 speed film. If we were going to shoot in low light or we wanted to shoot action photos, we selected "fast" film - 400 or above. Digital cameras work the same way. On most of them we select the ISO value just like we used to select our film speed. 100 ISO is less sensitive (slower) than 200 ISO. Some cameras go all the way to 3200 or even 6400 ISO which is very "fast."

A good exposure - one that results in a good photograph - is a combination of sensor sensitivity (ISO), aperture size, and shutter speed. All three components work together in different combinations to give us what we want. But exposure is only one part of the puzzle. Shutterspeed, aperture, and ISO each affect the quality of a photograph in other ways that we will cover in-depth in future lessons. If you can understand the effect of each parameter, then you can consistently make amazing photographs. That's our goal - to get you making amazing photographs.

So now you know how a camera works. Great! The next thing you need to do is learn HOW TO CHANGE the ISO setting, the aperture, and the shutterspeed on YOUR camera. How do you do this....


While you're doing that, enjoy another one of my all-time favorites: Tulips in Sweden

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