One of the good things about DSLRs is that you can crank up the sensitivity much farther than you can with a point and shoot before sensor noise overwhelms the image. But at ISO 1600, even DSLRs start to lose detail and color - so what to do?
Andy Rouse[a] recommended ISO 800 or 1600 for shooting in black and white, for the "lovely grainy effect" (Wildlife Photography[b], p.99). This is a test of the corollary: When forced to shoot at high sensitivity - will the resuling image look better if converted to black and white?
Actually, no, not quite. I found that just desaturating the image made it very cold. To compensate for this I mixed in 20% sepia in the gray and brightened the image a little, so the original white point ended up approximately at white. That turned out quite nicely.