thanks for the reply.
high ISO, slow shutter speed, and F2.8 because it's under the low light situation. i try my best to balance the brightness of the images.
yes, i dint use any flash.
however, i tried few shots again this evening, and this is the outcome:
24mm, 1/100, iso100. F2.8
24mm, 1/1000, iso100, F4
17mm, 1/20, iso400, f2.8
and oh, i dint blame the lens, i blame myself for duno how to perform the lens