Hi i dont tend to use the higher ISO settings much mostly because of the noise on the images, i shoot mostly use ISO 50 or 100 for better quality ... but i use a tripod and shutter switch, when i cant i borrow a person or a wall to lean on and turn the ISO upto 200 and then shoot, i very rarely go above 400 even though the 5D is pretty good on reducing the noise... old habits dye hard