iso speeds

playing with my 40D and took these pictures. cut them to 30% of its original size and downsampled it.
at its original size, you could see the difference between a picture taken at iso 100, 400, 800, 1250 and 3200. but after resampling, the pics below look the same except when you bump it up to iso 1600 and 3200. so the conclusion for part one is if its for web posting, iso1250 is still acceptable but for zooming in and close scrutiny, you can really see the difference with each increasing iso step.

iso 100


iso 200


iso 400


iso 800


iso 1000


iso 1250


iso 1600


iso 3200


next, i cut out a tiny portion from the original pictures to see the fine details when cropped. its obvious that noise is introduced at every iso increase. i find that iso1600 is still generally usable. but in tight situations, even 3200 is acceptable, even though the noise is horrid. better a grainy and noisy clear picture versus a blured out sharp one - or no picture at all.

iso 100


iso200


iso400


iso800


iso1000


iso1250


iso1600


iso3200