OK, yet another help me choose a lens thread but I am a little in need of ideas. Money is tight so I don't want to get the wrong thing.
At the moment I have a 16-35L (mkI) and Sigma 12-24. Both are good.
I am keen to get much sharper results, in most cases I will be on tripod using Live View so lack of AF isn't a biggie.
Option One - Sell both Sigma and 16-35 and get the Nikon 14-24 and adapter.
Option Two - Sell just the 16-35 and find cash to get the Zeiss 21 ZE.
Option Three - Keep Sigma, sell 16-35 and get 24-70 (sharper at 24mm than 16-35).
Option Four - Sell 16-35 and get the 24L mkII.
My 24-105L is up for sale on fleabay so that will hopefully add some cash.
Argh. Too many options..... Ideas on a postcard PLEASE 

. However, it still is an excellent lens.
