I've had the Fuji Natura 24mm, and the Fuji Tiara. Still have the Tiara, but it doesn't focus anymore. Sold the Natura while the selling (and the function) was good, because the fancy Fujis are not built to last; they are fun while they last though. I would take the Vivitar Ultra Wide and Slim (or Ansco Pix Panorama, same plastic fantastic) over them because they are simple and still working after many years, and the ultra wide niche may not deserve a more expensive solution. Another one (not cheap) is the Soviet Russar 20mm f/5.6 -- all the talk about compatibility between FSU lens and Leica backfocus shouldn't matter at this width, and the Russar's viewfinder is so good you'll keep it even if you don't keep the lens. It's aluminum and very light as well; Russar on a Cosina Voigtlander body would be a sylph. Speaking of CV, since they go down to 10mm now, maybe deals can be had on the 15mm Heliar-- it's a nice lens.