what is ISO and how it affects your photographs (part 1)

Posted by jason on Aug 31, 2009 | Comments Off

think of ISO as how sensitive your skin is to the sun. take either of my sisters growing up (or me for that matter), our skin was very sensitive to the sun and would burn very easily. on the other hand you have some people who can lay in the sun for hours and not get burned.

so, in this analogy our skin is the sensor and we have the ability to change how sensitive our skin is to the lovely sun by using sunscreen. do i want my skin burned, lightly crispy, or pasty white?

using ISO 200 on our camera is like applying a moderate amount of sunscreen so we stay looking “normal”.

each time we double the ISO we half the sunscreen and eventually we end up looking really burned because we didn’t use any sunscreen and our ISO is at 1600+.

in order to get this example to work we have to keep the shutter speed constant (in this case 1/400) as well as the aperture (f4)

here is our original photo at ISO 200 (lots of sunscreen to stay looking normal)