Capturing a moment and capturing a specimen are not so very different: Both acts take an acute eye and some cunning; and in either case there’s a chance you may kill what you mean to preserve. If the flora and fauna in Jochen Lempert’s photographs escape such a fate, it is because he photographs nature without making nature photographs—no small achievement for a photographer who depicts wildlife in abundance, from cormorants and gulls to sponges, flies, and plankton, who shows us both the North Sea and the full moon. “Field Work,” a remarkable body of recent photographs by the German artist (