[Charity]

I work with black and white photos, and occassionally I get a picture that is very dark. However, in some photos, when I try to lighten them a haze forms in the areas that were dark. Its as if there was a cloud in the foreground. Does anyone know what causes this for some photos? Also, what would be the best way to evenly lighten the entire photo?
Thanks

[godzookie2k]

I use curves, its a bit more precise than levels or brightness contrast. For some photos where this is happening I'll go in and select sections with a high feather and lighten up a photo section by section, and/or go in and dodge/burn little by little.