What is aperture and how can you use it for special effects?

You have probably heard about the aperture or f-stop but you have not paid any special attention to it. That is OK, you will do well without. However when you have learned how to actively use this setting, you will never stop using it again (you will probably regret you did not know its possibilities earlier)

Aperture
Determines the size of opening in the lens and control how much light will be let in into the sensor. The lens opening in combination with shutter speed and ISO settings will give a correct exposed picture. Letting the cameras metering system handle this will in most situations give you a perfect exposed picture.

The standard scale
The standard f-number scale consists of successive increasing numbers, each of them halving the amount of incoming light.

It does not sound logical the value of f4 let in double as much light as f5.6. If you did not know you would guessed f4 let in double as much light as f8 – that’s the logical math. But we just need to accept this as there are some advanced formulas behind the calculation.

The important thing is to know that setting of f2.8 let in much light while a f22 almost closes the lens and let inn very little light.

Swap your mouse over the photo to see the effect of dept of field

Generally you get a shallow DOF when the setting is f2.8. In this case the parts of the photo which is not focused will be blurred. Typically a shallow DOF is desired when you don’t want the background to disturb your main foreground motive.

A setting of f22 will keep both the foreground and background in focus. How much effect you will get is also very much dependent on the type of lens used.

Lens speed
The lower f-stop value a camera or lens has the better it is. The term “lens speed” is often used to describe lenses. This refers to the lens maximum opening.

Lenses with f-stops of f1.4 or f2 are referred to as “fast” lenses. They are called fast because they allow shooting at fast shutter speeds (high value) and still allow enough light for a correct exposure.

Very few digital compact cameras have “fast” lenses. For DSLR cameras all manufactures offers fast lenses, but they tend to be quite expensive.


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