I photographed a rather cooperative, large dragonfly today and after getting back to my desk and looking closer at the images I realized that the reflection of the Sun in its eyes produced large hexagonal bright spots that are:
- much larger/wider than if the eye surface were smooth specular reflector
- relatively uniform in brightness all the way to the edge
- have very sharp edges, transition from bright to dull red is very abrupt.
I'm aware that the components of compound eyes are usually at least roughly hexagonally packed, but what is happening here is something more than that.
What is it about a dragonfly's compound eye that can account for all three of these characteristics of reflected sunlight?
Presumably this is the same red dragonfly species as is seen in Identify these two large, colorful dragonflies in Taiwan? It's the same area and time of year.
Two more taken at different angles relative to the Sun. (click for larger)