Almost all of my macro images of insects are composed with the subject facing the lens but I tried something a little different here by composing the fly vertically to show a 'top-down' view. While the depth of field was still insanely shallow at this magnification and working distance, I didn't have to cover a lot linear distance with this composition - 3.7-mm to be exact - and the results gave me a very clean focus stack since the stacking software didn't have to resolve lots of out-of-focus edges over a long distance of travel. For the background I used a small piece of red and gold wrapping paper. The vignette occurred naturally from using a reversed-lens aperture controller.
Nikon D810 ~ ISO100 ~ Nikon 85mm f/3.5 Micro at 1:1 and f/16 ~ Reversed Nikon 50mm f/1.8 shot wide open ~ focus-stacked from 37 frames exposed at 0.6-second with focus adjustments at 0.10-mm increments.