High ISO is certainly one to approach with care although, to be fair, I have sometimes found that boosting it up from my standard setting of 200 makes a world of difference between being able to take decent pictures and ending up with a blurry or overly dark mess.
In an "almost no light" situation like a dark forest, you will probably need to use a long shutter speed, even with a high ISO, and there it is probably better to keep the shutter open a few seconds longer instead.
Wulf
__________________
Wulf Forrester-Barker << Sites: blog / flickr >>
Gear: Nikon D40, Nikon AFS 18-55mm f/3.5 - 5.6G, Nikon Series E 50mm f/1.8, Nikon AF 70-300mm f/4-5.6G, Vivitar 90mm f/2.5 macro, Raynox DCR-250, Lensbaby 2.0k, SB600
|