Well my copy has a usable iris range from f2.0 to about 3.8. From approximately f4 to f11 the image looks like someone took and put Vaseline on their finger and smeared it on the center of the lens. This is a documented issue with these lenses, at least some samples, how may are effected is unknown. I strongly suggest buying them from a reputable dealer so that you can return them if you are not 100% happy with the lens. Do not buy them direct. When I contacted SLR, where I bought the lens, they blamed it on sun flares and refused to do anything about it. I went so far as to waste money renting another copy of the lens from one of the popular rental houses and it had the same issues. The other issues being nasty flares when opened up beyond f2 when any light source hit the lens and the mount adaptor on my lens and the rental lens had way too much play in it. Hopefully my experience with this company helps someone.
Wayne Mann
www.HeliCamHDmedia.com
Wayne Mann
www.HeliCamHDmedia.com