Tutorial - Exposure

The exposure of a picture is the amount of light that hits a digital camera's sensor. A properly exposed image is one where there are minimal black areas and minimal white areas. However, there are times when you want the picture to be brighter than the proper exposure. These pictures are called over-exposed, as the sensor is exposed to too much light. This usually results in the loss of detail in the highlights. When you lose the detail in the highlights, they show up as pure white (too much light) in the picture. Likewise, there are times when you want the picture to be darker than the properly exposed image. These situations you will want to under-expose the image. This means that the sensor did not get enough light. When you under-expose the image, you will lose detail in the shadows. Changing the amount of light hitting the sensor by halving or by doubling the amount is called under-exposing or over-exposing by a stop of light.

So, the question becomes, how do aperture, shutter speed and ISO affect each other. Just to recap the settings -

Aperture

Aperture is the hardest of the three concepts. Every time you change the F-stop by a step 1.4 - 2 or 2 - 2.8 you halve the amount of light. Adversely, every time you change the F-stop to a smaller number, 4 - 2.8 or 2.8 - 2, you double the amount of light.

(If you want a more in-depth explanation, check out our full tutorial by Clicking Here)

Shutter Speed

Shutter speed is probably the simplest of the three concepts. If you double the length of your shutter speed, (1/100th of a second to 1/50th of a second) then you double the amount of light hitting the sensor. Likewise, if you halve the amount of time your shutter is open, (1/100th of a second to 1/200th of a second) you halve the amount of light hitting your sensor.

(If you want a more in-depth explanation, check out our full tutorial by Clicking Here)

ISO

ISO is the sensitivity of your sensor. Every time you double your ISO, you require halve as much light because your sensor is twice as sensitive. Adversely, when you halve your ISO, you require twice as much light because your sensor is not as sensitive.

(If you want a more in-depth explanation, check out our full tutorial by Clicking Here)

Exposure

Here is a diagram to help make things easier.