The floor of the crater is dry enough by this time of year that the herds raise dust just by moving. This group of zebra came through a low haze of it, half in and half out, the ones behind already going soft.
It is a frame that wants both treatments. In colour the dust warms the whole thing, the gold of the ground carried up into the air. In black and white it turns the herd into shapes coming out of a fog, the stripes doing the rest.
Both the 135 at base ISO 64. Same second, one decision about what the picture is: the light on the dust, or the animals emerging from it.