Lens aperture, shutter speed and ISO are the three primary adjustments available to achieve a properly exposed photograph. These settings can also affect the image quality and artistic effects of your photography.
The aperture is the size of the opening in the camera lens at the moment a photo is taken. Aperture is measured in fractions, so the larger the number, the smaller the aperture opening. Shutter speed and aperture are the two primary controls for limiting the amount of light that hits the camera sensor. Aperture also controls the depth of field. A small aperture will produce a photograph with almost all objects in focus. A large aperture will produce a photograph with a small amount of the objects in focus. This will give you control over what you want in focus. That is why I primarily use the aperture priority camera setting in my photography.
Typical apertures include: f1 f1.4 f2 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45
Camera Shutter Speed
Shutter speed is the amount of time the shutter remains open when a photo is taken. Shutter speed and aperture together determine just how much light hits the film or camera sensor. The shutter speed is also a fraction, just like the aperture. A shutter speed of 500 is actually 1/500, or “one five hundredth of a second. To hand hold a camera, the rule of thumb is a 50mm lens can be hand-held at 1/60 of a second. A 200mm lens at 1/200 of a second and so on. To achieve this you can adjust the apertures or the ISO settings.
Typical shutter speeds: 30s 20s 10s 4s 2s 1s 1/2s 1/4s 1/8s 1/15s 1/30s 1/60s 1/125s 1/250s 1/500s 1/1000s 1/2000s 1/4000s
Camera Sensor ISO
The sensitivity of film or camera sensor is measured by ISO, and the larger the number, the more sensitive the camera sensor. ISO 100 needs a lot of light, like outdoors on a sunny day. ISO 1600 doesn’t need much light. However, higher ISO means more grain in the film and more noise in digital. Digital images borrow the ISO scale to measure the sensitivity of film. Just like the grain that’s added to film at higher ISO settings, more “noise” is added to digital images at higher ISO. In general, as ISO goes up, quality goes down. Some of the new mid to high-end D-SLR have improved the noise levels at the higher ISO settings up to ISO 1600. Some of the new cameras have ISO settings between 100 and 102400.
Typical ISO settings: 50 100 200 400 800 1600 and high ISO 3200 6400
My basic camera settings I use related to this article are: ISO 100 for best image quality and set camera to aperture priority. Also, use a tripod when ever possible. All three settings work in concert and affect proper exposure. All have their advantages an disadvantages, so experiment with all of these settings and you will become a better photographer.
Hear is a nice Exposure Chart
Doug Niedermiller Photography