I have a friend and Seacam client in Norway shooting orcas at the moment. It is a challenging shoot because there is very little daylight, forcing him to shoot nearly wide open at high ISO to be able to stop the action. It is impossible for him to do a pool test so I thought to do a semi-controlled test of 2 possible lenses he might use. We already have good data on the 16-35II and recommend a 57.5mm port extension and Superdome for that one, but it was worthwhile to try to dial in the new 24-70mm II F-4 L IS and the 14mm II F-2.8. I wouldn't use either lens at F-4 normally, preferring instead to get to F-8 or smaller, but as this is the world he is forced into at the moment the challenge became to get the best we can out of corner performance at F-4. Canon 5D3, Seacam housing, swivel 45 viewfinder (no reason to get all the way wet on this cold morning), Superdome, Wideport, and either a +2 or +4 diopters were tested (only the 24-70mm II F-4 L IS would accept diopters of course)
pooltest2.JPG 293.24KB 91 downloads
The results came out looking like this:
Screen Shot 2014-01-23 at 11.19.32 AM.JPG 145.56KB 108 downloads
But, I guess the final analysis is with enlarged views of the corners.