For those of you who don't know, ISO on a digital camera is effective to film speed. The higher your ISO (also known as ASA), the more sensitive your sensor is to light. This allows photographers to shoot in low-light situations, with a faster shutter speed. Also, the higher your ISO, the more grain (also known as noise) your image has. ISO 100 and 200 have effectively no noise, whereas above ISO 800 you get a lot.
More badass camera bodies like the Nikon D3(s) and the Canon 5d MK II+ can go to ridiculously high ISO without too much grain.
The grain is what gets me. I love the raw feeling of a grainy photograph. It's almost as if it's more real, more alive, more real-life.
It rained a bunch in Flagstaff this week, so here are a few non-people photographs for a change.
I'm pretty sure I shot all these at ISO 3200. The top one might be as low as 800.
I've been doing some high ISO portraits too - I'll post one or two of those in the near future.