Here's a casual blog of my shoots, outtakes, adventures, and probably what I ate for lunch.
It depends on the light/time of day/angle. Sharpest eyes = dead sun. But you have to be very creative and careful not to make them look unprofessional or blown out in dead sun. Backlighting they’re softer, but if you expose for the person they’ll be fine. The darkest eyes come from cloudy days… but move the person 360 degrees and you’ll see the light on their face change. Cloudy, move them in direct “light”