While I'm an experienced terrestrial nature photographer, I am a complete novice with underwater so I could use some advice and the reasoning behind it. Let me explain what I'm looking to do and the gear I have.
First of all, I'm photographing to print and print large. I print on canvas and metal a lot of times 5' or larger. With my terrestrial work, detail and sharpness has been one of the hallmarks of my work so it is imperative that I keep that as much as possible underwater. I will be on a liveaboard trip mostly snorkeling for dolphins with a few dives added in the Bahamas in the next month and that is my primary concern right now. After that I have short-term plans for sea turtles, alligators, and freshwater animals. Eventually I'm sure I will move into macro, but for right now most of the work will be wide angle and with a good amount of over-under in the near future.
Budget is an issue as I just bought a camera and housing for underwater, will need a port/lens, and at the same time I am opening a gallery with my artwork. On the other hand I need to capture images of the best quality to print large or else it doesn't do me any good to save money. So my approach is to start with minimal gear needed to solve some of the initial situations and the increase the possibilities with additional gear in the future when budget becomes available.
I'm in the process of purchasing a used D800 with a Subal housing. Keeping in mind the snorkeling with the dolphins, I'm thinking of starting with just a wide angle. I'm considering both the Tokina 10-17mm and the Nikon 8-15mm. I know the Tokina will only work from about 15-17mm without vignetting, but on the other hand the Nikon is really only either a 15mm or an 8mm and while the circular fisheye images look cool viewed on a screen I'm not sure if they make an art print (please tell me otherwise for anyone who has printed these type of images large). Also I have a D500 that the 10-17mm could work well with if a second housing was in my future but realistically that's won't happen for several years. The image quality might be leaning me towards the Nikon even with 2x the price tag. Any recommendations between these two in my situation? Also, is this the right focal length I should be using with the dolphins or is another range better suited?
Without fully explaining my situation, ReefPhoto recommended a Zen DP-170 port. The $1000 price tag is much nicer than the $1500 Subal DP-FE4, but 170mm is only 6.7" inches vs the 8" of the Subal port or the 9" of a Zen 230mm. From reading Alex Mustard's Underwater Photography Masterclass I was under the impression that for wide angle shots a larger port is preferred for edge to edge sharpness and also for over-under work.
Last questions are regarding lighting. I was considering trying to photograph with just ambient light since the depths will be shallow and I was thinking a bright sandy bottom would also reflect up a good amount of fill. Secondly, no strobes would give less drag for moving with fast-moving dolphins. Also, I know nothing about underwater strobes except from reading Alex Mustard's book and initial price checks look like it would add $1500+. Is my image quality going to be lacking without strobes either in terms of color cast or unattractive shadows? If I really should go for a strobe setup, would a single strobe be ok or are 2 necessary in this case for best results? I know I will be getting strobes eventually but if it won't make much of a difference in this situation I'd be happy to delay the purchase until I know more of what I'm doing.
Thank you and sorry for the long post,