Making Sharp Photos Handheld
I have from experience that handheld shooting with large and heavy cameras can yield sharp images down to ridiculously low shutter speeds, provided that one accepts that 2-4 frames might be needed to yield one frame that is crisp.
By “large and heavy” I mean cameras like the Nikon D3x or Canon’s 1Ds Mark III (lots of material on both in DAP).
I dislike small cameras like the Nikon D200 for low light shooting; less mass (and perhaps a less well damped shutter) means a lower success rate under marginal conditions, or so I’ve concluded from years of experience.
In addition, the handheld technique I’ve developed relies on stabilizing the larger camera body against my face, something not really feasible and/or quite awkward with the smaller camera bodies.
Example
I took two frames, both at 1/4 second at ~/f8, handheld at ISO 1600 with no support (just free-standing). The successful frame is not critically sharp, but it’s awfully good for 1/4 sec handheld, especially keeping in mind that the 1DsM3 is a 21 megapixel camera; the image would stand up to fairly high enlargement.
The point here is that sharp images can be made at very low shutter speeds—this is not a one-time freak accident. By shooting 2-4 frames, chances are good that one of them will be sufficiently crisp for even fairly large prints—I do this all the time, though more commonly in the 1/15 - 1/60 range.