Is Tamron 1.4X Pz-AF MC4 TC Really FF?: Pentax SLR Talk …
1. A few minutes ago I did quick an dirty test. No tripod, all handheld, with no intent for the ultimate IQ. However, it looks like old Tammy goody does AF with K-1 and D FA 150-450 with almost no vignetting at both 150mm and 450mm ends wide open (just a bit). At least vignetting from HD Pentax-DA 1.4x AW AF RC is much more pronaunced.