Yeah, going back to the original topic (though I have really appreciated the other branches too) – two questions about that.
1: correction lenses. Sea & Sea for example sells 77 and 82 mm correction lenses for wide-angle zooms behind domes. Can it be reasonably assumed that these will work decently on all wide-angle zooms? Presumably the correction lenses don’t correct for aberrations in the zoom, but rather correct for the effects of a dome. In that case they should work more or less the same for all wide-angle zooms.
(This feels like a very beginner-y question but, well, this is the beginner forum after all.)
2: more on what makes a wide-angle zoom suitable for use in a dome. Presumably, again, this is not primarily about topside performance, but rather whether it’s possible to place it at a good spot relative to the dome. Which, in turn, should depend on
a) whether there are port extensions of suitable length
b) whether the critical position of the zoom changes notably when the focal length is adjusted. The critical parameter I assume is not the front lens’ position, but rather front principal plane or something other which can’t be deduced by just looking at pictures of the lens.
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I have the Nikon 16-35, used on both D810 and D850 behind 230mm Nauticam dome port.
When I bought the (very very large) dome port, it was with the understanding that I would get 'good' corners. The bigger the dome, the better the corners is what I was told. They'd better be good to justify carrying and packing that dome!
And I was disappointed when I used the lens underwater. With or without the recommended +2 diopter. (I never noticed any quality improvement or difference at all with the diopter).
In March I bought the Sea and Sea 77mm internal correction lens, hoping for decent improvement. When I saw the first results, I was shocked. The improvement was night and day. I can't imagine not using this lens anymore.
Wide angle pics from my March trip start on page 15 here: http://www.cjcphoto.net/roatan2019-1
The specs say a "2-stop improvement". Maybe that's true, but it seems a lot better than just stopping down that much.
What makes a wide lens suitable for a dome? Close focus ability for sure, but I'm not clear otherwise. Why is the 16-35 supposed to be better than the 14-24 underwater? I don't know. Perhaps it has to do with also having just the right extension? My 230mm dome port came with a 90mm extension recommendation from Bluewater Photo. Some recommendations are for a 70mm extension, but the 90mm recommendation is newer. No idea the difference though.
Anyway, I was disappointed before with the 16-35 and 230mm dome port with 90mm extension. I cropped all the time to clean up the edges. No longer. I'm very happy with the rig now that I've added that S&S 'filter'.
