Originally posted by northcoastgreg If you're going to sell the DA 12-24 because you need something even wider, why settle for 10mm when you can get 8? 8mm may not be much wider than 10, but then again, 10mm is not much wider than 12. At least with the 8-16, you know got as wide a rectilinear as will likely ever be made.
With ultra wide-angles, 2mm is a big difference (8 is 20% wider than 10 and 33% wider than 12).
The 8-16 is a very solid lens, but weather-sealed it is not and the front glass might be a vulnerable in a dusty environment (and it has that weird cap). But if you want the widest of the wide, that's the one. The 10-20 is probably easier to use (and keep protected) -- haven't used it, but is a more normal shape and size -- and if you are using it mainly outdoors 10mm is still pretty wide and the less extreme 17-20 range is available. Can't go wrong with either one of them, just depends how extreme you want to go. (I think I use my 8-16 mainly in the 10-12 range.) The aperture difference is pretty much a non-issue for a lens like this -- stop it down, you can afford a slower shutter at these focal lengths...