Downs Photography wrote in post #12178829
5d mark II your lenses are perfect for it!
Except that your 70-200 will no longer act like a "112-320".
You are at a crossroads in your life, Grasshopper. You must choose between the way of the full frame, or the path of cropped sensor.
Either way will get you where you want to go, but each will feel a little differently to you and will have some pluses and some minuses along the way. Crop = more "effective" reach with potentially smaller, lighter lens kit, but not-a so wide-a without another special lens, but generally "faster" handling camera. Full frame = bigger image files to fill up hard disks and memory cards, slower focusing, ultimate fine detail short of the mythical land of Hasselblad or Leaf/Mamiya, overall a potentially larger, heavier, more expensive lens kit if Grasshopper wants to cover the same effective range they had with crop sensor.
Mull these over carefully with your mind. Weigh your wallet and check your credit card balance, Grasshopper. Choose what is most important to you.... Slower shooting and a bit heavier, more expensive kit, but max detail, enlargeability, low light performance, with lotsa that bokeh stuff smeared around on top. Or perhaps Grasshopper would rather do fast shooting with a little smaller, lighter kit, maybe less expensive, but still very fine images, faster AF and 8fps... Like Ninja!
With crop, besides the Canon EF-S 10-22 ($850 US, by the time you get the lens hood that's not included), Grasshopper might also consider Sigma 10-20 (about $490), Tokina 11-16/2.8 ($600), Tokina 12-24/4 ($500), and several others.
Sensei bought Toki 12-24 a couple years ago and still considers it the best value in this class if it's wide enough for Grasshopper. Sensei thinks f4 is fast enuf for UWA, 12-24 Toki is more "L-like" than some actual Ls, and only the Canon is "better", tho not necessarily $350 "better" (2mm wider and a little more flare resistant, but perhaps not as good "build").
With full frame, Grasshopper would not necessarily need to buy another lens, so long as 24mm is wide enough and 200mm doesn't now fall short of Grasshopper's expectations.
If not wide enough, Canon EF20mm f2.8 is about equal to 12mm on crop camera. Or there is 17-40/4L if you prefer a zoom.
If more telephoto is needed, then one option is Canon 300/4L IS. It's a good lens for handheld shooting, reasonably portable, and work well with 1.4X if you wish. (Sensei must tell Grasshopper that 300/4L also works well on crop camera... Where it feels much more powerful!) Alternatively, if Grasshopper prefer zoom, there is 100-400L IS.
Or, if Grasshopper won Lottery and has assistant to carry it, there will be 200-400/4L IS 1.4X Extender lens later this year (might be delayed due to earthquake and tsunami).
Decide, Grasshopper. Decide.