I shot against fairly brightly-lighted Photinia as my background. These tall shrubs are about 15 feet high,and had very,very small dappled patches of sunlighted highlights on just a few leaves. Those leaves are about 30 feet behind the butterfly,and those little dappled patches of sunlight are what give the background its slight feeling of texture. The Sigma 180 EX Macro does a good job of rendering these out of focus highlights when such highlights are not brilliantly lighted, which is the case here. Having the ability to synch flash at 1/500 to turn brightly-lighted foliage into the _equivalent_ of a dark background is very,very nice. Electronic flash is my FOREGROUND lighting,along with some daylight. But the Photinia are in backlight,and are receiving less light from the sun than the purple plant is. 1/8 power Minus 1/3 stop flash is enough to illuminate the butterfly and purple plant, and 1/500 at f/13 at ISO 200 makes for a nice,controlled background brightness rendering. To me, this is very good synchro-sun flash with the D70 and SB-800 speedlight with its supplied diffusion dome.