The lens looks really sharp and even cropped at 10mp on the A99 its rather impressive. The details on the flowers are incredible
The A99 images aren't cropped... It's a full frame lens. That's 24mp of full resolution you are seeing.
Take a look at the portrait of my wife and our friend. Wide open at 2.8. Yes, there was some post production work, but absolutely no lens corrections. Pretty darn sharp corner to corner. Go ahead and pixel peep. I'm thinking of ordering a blown up copy of that one.
I'd easily say that the 50 macro is the sharpest lens I own, corner to corner. Followed by the Sony 16-50 2.8 zoom. (but that's a crop lens). On the next tier of sharpness, really like the Minolta 135/2.8., Sony 85/2.8, and the Tamron 70-300 usd. Still very sharp, would be the Minolta 70-210 f4, Minolta 35-105 and the Sony 35/1.8. More mediocre would be my Tamron 10-24 wide (still get sharp images thanks to the short focal length though), and the Minolta 50/1.7 (still sharper than most zoom lenses, but not as good as other primes).
And sitting on a shelf never to be used unless lenses break, would be my Sony 18-70 kit lens.