Looks almost like a perfectly round crater filled with water. Awesome photos.

Similar website for a range of animal eyes. Just amazing:

http://slickzine.com/nature/close-up-with-nature-amazing-animal-eyes/

Bonus points for guessing each animal correctly before reading the caption.

^ You're probably better off popping that model into google and reading forum-based user reviews/comments.

Pretty much every brand-name lens has got plenty of forum threads around the place comparing it to similar cheaper or more expensive lenses in terms of sharpness, speed, auto-focusing ability/speed/noise, chromatic distortion, etc.