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... The housing price is about half that of the Nauticam. But once you add ports, strobes, focus lights and so on, the price difference is not that much.
The D7100 has a 1.3X Crop Mode. So, one 'could' argue to skip using the 1.4TC + Tokina 10-17mm and just use the Tokina alone in Crop Mode (and save the additional cost of the TC and port extension).
The downside is Crop Mode reduces the megapixel size from 24MP down to 15MP (which is still reasonable).
This is a shot of two Gobies on a whip coral that I took with the Tokina 10-17+ Kenko Pro 300+ Zen Mini combo. Snooted via fiber optics, dome about an inch or two away from the gobies. And yes, the AF is very slow. This shot took about 20 minutes to compose and it is still cropped about 20%. As you can see, you can't expect to get GREAT depth of field to where the surface of the water, or a diver in the background would be sharp (All the photos you see with tiny macro subjects with a sharp foreground+background are achieved by double exposures). This was shot at F20 and that was the best I could do with the sunball at this time of day. The AF is so slow in fact, I had trouble getting anything moving, such as anemone fish, in sharp focus. I still don't understand the versatility. If sharks are getting close, such as in a feeding situation, the tokina alone would suffice. If they are further away, say a couple of feet, I would want a lens with AF fast enough to get the shot I'm after (ie change lens to 10-24). Realistically, I can't foresee a situation where I would need a lens that allowed me to shoot a scorpion fish and a great white shark on the same dive, or even succesive dives. My kenko combo performs so slow I wouldn't chance it with shooting sharks period. Maybe I was unlucky and got a faulty version.Dont know about you but my Tokina 10-17mm with the Kenko pro 300 1.4x TC focuses quick. Putting the TC on the tokina turns it into a very versatile combination especially when you dont want go out and buy a rectilinear zoom like the Nikkor 10-24 or tokina 11-16. Shooting with a min dome with the Tokina TC combination you wouldnt be shooting Gobies or anything skitsh like that your shooting stuff which doesnt move much like Scorpion fish with a nice background and at the same time you can shoot that same combination behind the bars of cage shooting GWS.
So I think the $150 Kenko 1.4x TC is an excellent additon to the kit bag with the Tokina 10-17mm. Its also great on the 60mm Macro if you want a little extra reach.
Regards Mark