When James first started this thread, I really took only passing interest in it. To be honest, I thought he was searching for an imperfect solution to a problem that we had already concluded wasn't worth solving, i.e., a zoom lens that would have inferior optics to prime lenses. Sorry James - I should have known you weren't going to all that trouble without good reason.
I (as most of you) had resigned myself to the "pick a lens and make the dive for that type of subject" approach to uw photography. However, I just returned from a 3-week trip to Indonesia, and for a week of that, I was diving Lembeh Straight with Don Silcock as my roommate and dive buddy. Don used a Nikon 70-180 and Woody's wet diopter, and frankly, I was AMAZED at the results Don he got with it! As I stated in another thread (where Don had posted shots of a rhinopeas and pygmy seahorse):
> If Canon made a comparable macro zoom lens, I'd order it the first day I got back. I must admit I've started falling into the "primes are best" camp (note the slightly upturned nose when I say that?). And I realize that if you're going for a specific target, you can pick the best (prime) lens for that situation from your camera bag. After diving with Don, however, and seeing how amazingly flexible the 70-180 is, I would almost view it as the "ideal" (realizing that word comes with flashing warning signs!) lens for a place like Lembeh where subjects tend to range between the two photo subjects Don posted. As he says, the Woody's diopter is a really important part of that flexibility (I'll be posting some impressions of my Canon 100mm with Seacam diopter after I get back, as there are some similarities). But often shooting the exact same subjects and comparing images at the end of the day, Don has left me in the dust (or more aptly, the silt) in more cases than not. That is partly a tribute to his excellent skills as a photographer, but his choice of the 70-180 + diopter certainly helped... <
Thus, while I realize that no zoom lens is truly a "Holy Grail," I am now VERY interested in the results you got with this lens, James...I might need one!
Oh, and I apologize for having doubted you, James! 