There is a phenomenon about close-up work that most photographers don't either know about or fail to exploit.
I am referring to what are called 'specular highlights'
These are most often seen as out-of-focus hexagonal shapes that show up in either your background or foreground when shooting close-ups of subjects that are surrounded by bright highlights
i.e. a single dew laden blade of grass surrounded by other dew laden blades of grass all brightly lit up by the early morning sunlight.
When shooting macro or close-up imagery, there is an optical law that goes into effect immediately!
The law is as follows:
ANY OUT-OF-FOCUS SPOT(S) OF LIGHT WILL ASSUME THE SHAPE OF THE APERTURE IN USE!