Of those three, which company makes the best lenses for Canon, Nikon, Sony, etc.? Which lenses in particular (zooms or primes) have you found to be truly outstanding? (Feel free to post some samples, or even one hundred percent crops) In general, I have avoided third party lenses, but going with top of the line lenses does get expensive-and I don't expect to get any richer as I get older and older. (For the record, I regularly shoot the D800E, the D3s, and the D7000. I realize that what might work alright with, say, the D3s might not be so great with the D800E. The only thing I have left with Canon is the T2i--itself a fine little instrument with good glass.) --Lannie P.S.: For what it's worth, these questions are inspired by having stumbled onto this review by Shun Cheung of the Tamron 70-300.