Thanks Alex, the 17-85 was my most used lens, to some good effect.
- had a serious problem with the 11-16 in that the 26mm eff seemed to exceed or be at safety zone to get fish in front of the fantastic coral - about 35mm eff worked much better (i'll use the Canon 10-22 in the future even though i like the quality of the Tamron). Perhaps this is a problem with my technique, but i also think the 8 inch dome increases the approach distance to many fish by at least a foot.
- we dived a number of new sites where we didn't know what to expect and the 17-85 was an excellent compromise - and there were schooling fish.
- used the 17-85 with the macro port for some muck diving and was able to get some larger critters as well as (fairly) small. The faster autofocus of the 17-85 vs the 100 macro was helpful - found 2 pair of cooperative pygmy cuttlefish on the next to last dive and spent some time with them - some good images but couldn't get the mating or feeding tentacle images
Also my first trip with fully funtiioning H&W ETTL and two flashes -- What a difference!