A Brief Understanding of the Exposure Triangle and its First Component ISO

Listed below are the three components within your camera that will affect the exposure (outcome) of your pictures.  One important item to note is that making a setting change to one element will automatically affect the other two elements.

The Exposure Triangle

1.       ISO Setting

2.       Aperture (aka f-stop)

3.       Shutter Speed

So what are these three elements and what do they do?  Well let’s start with ISO.  The ISO measures your camera’s sensitivity to light.  So when you are adjusting your ISO you are determining the amount of light needed in order to get a good exposure.  But keep in mind that the ISO can impact the quality of your pictures.  Higher ISOs can introduce noise (aka grain) to your photographs. 

The second element of the exposure triangle is the Aperture (aka F-stop).  This setting allows you to adjust your lens opening.  The larger the opening the more amount of light will enter the camera.  Aperture is measured in f-stops such as f/3.5, f/2.8.  One would think that an f-stop of 3.5 would allow for a larger opening of the lens; however it is the opposite.  The larger the f-stop the smaller the lens opening.  Therefore, an f-stop of 2.8 has a larger opening then an f-stop of 3.5.

The third element to the exposure triangle is the shutter speed.  The shutter speed is the amount of time the lens shutter will remain open.  The longer the time open the more light will be brought in for the exposure.  Most shutter speeds used are 1/60^th of a second or faster.  If you use a shutter speed lower than that you will most likely need to use a tripod in order to eliminate camera shake which will cause blurred images.

How to Set My ISO

So how do I determine my ISO setting?  Well if you are in a brightly lighted area or outside in natural sunlight you would use a lower ISO setting such as 100 or 200 or maybe even 400.  However, if you are indoors in a poorly lit area you would need a higher ISO setting.  For example, I usually set my ISO between 1800 and 2500 while I am shooting my son’s basketball games.  The lower the ISO used the sharper your image; therefore, you should try and stick to a low ISO whenever possible.  However, there are several reasons why you would need to increase your ISO which would be:

1)      Not enough light for you to compose a good picture.

2)      To obtain a faster shutter speed

3)      Freeze motion (sports)

Listed below is a very helpful article and video from the www.imagemaven.com on ISO. 

What is the best ISO to use?