This image is an excellent example of the complex relationship between depth of field, illumination and the inherent difficulties in trying to produce solid macro images. The DOF, even at f/16 is only about 7mm. Not much room for error in focusing.
Pentax *ist DL
,Sigma 180/3.5 EX DG APO IF AF Macro 1/180s f/16.0 at 180.0mm iso200 with Flash
full exif