The 20 really is a nice lens. It's two issues are the size and heft, and it also has falloff until you stop it down a bit. At f:5.6 the falloff is mostly gone, all gone by f:8. I got it for $100 because one of the internal elements has a scratch, which has so far (16 years) had no noticeable effects in the photos. Otherwise it's a nice contrasty lens, flare is well controlled and the aperture ghosting can give an interesting effect sometimes. I never liked ultrawides until I used this one for a while.
Originally Posted by rich815