Recently returned from a great Bonaire visit. Stayed at Black Durgeon Inn for a week and than attended the Diving Medicine Course at Plaza Resort.
Here are some UW pictures http://andresmith.speedalbum.com/Bonaire%2...uary%20%202010/
I travelled with my 5D2 only and tried a couple of cropped sensor lenses with a 1.4 teleconverter. As I have both cropped and full frame Canons I thought I would try this to potentially cut down on the number of lenses I would need when travelling with both systems.
The first is the Tamron 60mm f 2.0 macro lens with 1.4 tele. Actually I have tried this on a previous trip and I am convinced that it is definitely as good if not better than the Canon 10mm macro. You can also get more than 1:1 as well.
The second is the Sigma 10mm fisheye with the 1.4 tele. I am sooo happy with this. Admittedly there is a very slight vignetting ( because it is so wide) but that is very easily cropped or cloned. The corners are great even at 5.6 ( and definitely better than my Sigma 15mm by itself ) I have attached a completely uncropped sample ( f6.3 )
I would happily travel with these two lenses and leave my full frame 15mm and 100mm lenses behind if space/weight is a concern in the future.