[font color=\'#000000\']You will always get less noise by increasing the ISO to get proper exposure than you will by underexposing and pushing in post. Read Digital Exposure And Metering Strategies
; by understanding and applying the concepts presented there, you will always know how to expose to capture the greatest possible dynamic range with the least possible noise. It's like abstinence as a method of birth control; it works 100% of the time it's tried. It's basically a refinement of Michael's "expose to the right" dictum, with test procedures for determining the exceptions to the rule.
Instead of raising ISO, try using a faster lens, or learning how to use bulb mode.[/font]