The above f-stop numbers are all standard options in any camera, although most also allow finer adjustments of 1/2 or 1/3 stops, such as f/3.2 and f/6.3
A photograph’s exposure determines how light or dark an image will appear when it’s been captured by your camera
Achieving the correct exposure is a lot like collecting rain in a bucket. While the rate of rainfall is uncontrollable
controls the sensitivity of your camera’s sensor to a given amount of light
One can therefore use many combinations of the above three settings to achieve the same exposure
With waterfalls and other creative shots, motion blur is sometimes desirable, but for most other shots this is avoided
Therefore all one usually cares about with shutter speed is whether it results in a sharp photo — either by freezing movement or because the shot can be taken hand-held without camera shake
How do you know which shutter speed will provide a sharp hand-held shot? With digital cameras, the best way to find out is to just experiment and look at the results on your camera’s rear LCD screen (at full zoom).
If a properly focused photo comes out blurred, then you’ll usually need to either increase the shutter speed, keep your hands steadier or use a camera tripod.
A camera’s aperture setting controls the area over which light can pass through your camera lens.
It is specified in terms of an f-stop value, which can at times be counterintuitive, because the area of the opening increases as the f-stop decreases.
In photographer slang, when someone says they are “stopping down” or “opening up” their lens, they are referring to increasing and decreasing the f-stop value, respectively.
By the Numbers. Every time the f-stop value halves, the light-collecting area quadruples. There’s a formula for this, but most photographers just memorize the f-stop numbers that correspond to each doubling/halving of light
or example, a compact camera might have an available range of f/2.8 to f/8.0, whereas a digital SLR camera might have a range of f/1.4 to f/32 with a portrait lens. A narrow aperture range usually isn’t a big problem, but a greater range does provide for more creative flexibility.
A camera’s aperture setting is what determines a photo’s depth of field the range of distance over which objects appear in sharp focus
Lower f-stop values correlate with a shallower depth of field
With compact cameras, an ISO speed in the range of 50-200 generally produces acceptably low image noise, whereas with digital SLR cameras, a range of 50-800 (or higher) is often acceptable
With many lenses, their light-gathering ability is also affected by their transmission efficiency, although this is almost always much less of a factor than aperture