actually its not totally due to handsteadiness loh; coz i was using pro-spec bodies with ISO400 film which means
(1)heavier weight=>more ballast like the base of a big ship
(2)less shutter lag=>less prone to register the effects of shakiness
(3)higher ISO of 400=> naturally the exposure meter recommends higher shutter speed, {assuming the exposure is "optimal" w.r.t personal taste}
so these few factors help in reducing overall shakiness
as for hand steadiness its very much like any form of shooting; body posture, support at elbows n at lens, tuck in "chicken-wing", synchronise breathing rhythm..pretty standard stuff, i guess
the 4 limits i suggested r more like the "absolute minimun", ie so usually u wont come across it much unless like an example some time back i sneak-shot a outdoorparty at chijmes at night 9+pm , ISO 400, exposure -1 compensated, 50mm, aperture f2, shutter speed @2 seconds..i was standing stiff & holding breath quite tight ;p
these "getaway" methods are fast n convenient n will help u getaway to a certain extent until u really magnify the pic to really see the "hidden blurness"... so for "really non-blur" picc, then yupz, external support (tripod, monopod, sandbag, etc ) will have to come in