I have a Nikon D90 with an 18-105mm lens (though I am unsure of the aperture range).
I get excellent results in good light levels (despite the body being somewhat outdated), but struggle in low light conditions without a flash.
Using a flash I am able to get some low light photos of close up subjects, but not of a wider subject matter (in particular bands on a stage at local gigs) without dramatically lowering the shutter speed, naturally resulting in slightly blurred pictures that are still dark.
Any tips for improving on this, or would I be better off investing in new kit?