Hi, currently I'm using my EOS 500D with Sigma 18-200m lens. I find quite difficult to shoot sharp images in low lightings without flash. Is there any ways to improve it? I tried playing with the ISO (Around 800~1600, 3200 too much noise), Shutter Speed ( max I go is 1/20) and Aperture (5.6), but some times still blur. Anyways to improve it? Must I get the powerful flash lights? Or shall I upgrade it to D7000? Pls advise. Thanks.