Lens Me Your Ears! (really Famous Quote!)
Here'a an interesting story about a really expensive lens and how it was overcome by a really inexpensive lens, in a lens race! For all of us that "only" buy the best,most expensive lenses and other gear,for that matter, this shows that sometimes it doesn't make sense to buy the most expensive "anything" if the cheaper version serves as well!
Leica Vs Sigma! $4,000+ and just under $1,000!
So keep this in mind when the next "lens" debate starts and the gear heads are all clamoring for the "bestest" out there of their brand. If you can afford the most expensive or your work demands the most expensive, then fine. But for most of us, good or even gooder,works!
http://fstoppers.com/zeiss-otus-bests-sigma-50mm-art-but-what-has-the-best-value
Rich