I own the 72mm 16x9 fisheye, but I thought it was only $450 retail (actually cheaper now with a 50 buck rebate)? I don't want to sell, but I don't want you to buy one from someone for more than it's worth haha. I might be looking at the wrong one though
the one from adorama is a different lens. both will work with the a1. the one from adorama has a 72-82 step up ring for the hvx. 16x9 made 2 different lenses, one geared a little more high end than the other. i own the more expensive one and i've used it with the a1 before, so i can attest to there being no vignetting and it being a good lens. i cannot comment on the cheaper one however.