what is ISO? what are some ISO settings?

ISO with digital cameras vs. our old film cameras:

Back when I had a 35mm film camera I had to decide which speed of film I wanted to purchase and shoot with. My common choices were film with an ISO of 100, 200, 400, and 800. ISO used to be ths speed of film (in film days) and now it’s essentially the same thing on our digital cameras. It’s the ISO equivalent, or how sensitive your camera’s sensor is to the available light.

Here are some examples of some of the ISO settings I would choose given different general situations. I would choose an ISO setting of 100 on a bright sunny day because it’s already bright and I don’t need any more light in my camera. I might choose an ISO setting of 200 or 400 when I’m in quite a bit of shade or on a cloudy day because I need a little more light. During the day, inside the house but near a window I might choose ISO 600 or 800 because it’s a bit darker but there’s still some available light. But last night in the evening, I put my ISO up really high because it was dark outside and I was inside my living room. I set it to 4000. In summary, refer to the little cheat sheet bullets below (they’re just starting places, ISO varies camera to camera):

• bright sunny day = ISO 100
• full shade or cloudy day = ISO 200 or 400
• inside the house but near a window = ISO 600 or 800
• inside the house in the evening no outside light = ISO 1200 and up

This picture below was shot in my living room under regular tungsten (lightbulb) light in the late evening, right before my boys’ bedtime. I did not use a flash. But my ISO was up high at 4000 in order to allow my camera to absorb more light. Higher ISO settings do allow the camera to absorb more light, but they can also create quite a bit of noise or grain in your image (the speckled dotted texture you see sometimes in a picture). But fortunately the professional grade cameras are pretty fabulous with high ISO settings, that’s part of what you pay for with a higher quality camera body. This picture was shot with my Canon 5D Mark II. It does a great job with high ISO. To me, it’s still pretty clear and great. One of the many reasons I love my camera body. :)

My manual settings:

ISO – 4000
shutter – 1/100 second
aperture – F 2.8