Tokina 10-17 with a dome and 1.4x question

I have a Sea and Sea 8inch dome I have never used. It is setup for Nauticam connections and I plan to use it with a D7000 in Nauticam housing.

I plan to use a Tokina 10-17 and a 1.4X for shooting humpback whales at DR soon.

I have no spacer to put between the dome and the housing. I do have the extended piece for changing focal length.

I normally use a 4 inch dome with the 10-17 and 1.4X but was thinking the larger dome would improve the whale shooting. Any comments on this?

Will I have any trouble with this setup?

My concern relates to the nodal point change from moving the lens forward but not the dome.

Thanks for any assistance.

Hi Dave

I've shot the Tokina 10-17 plus 1.4TC combination on DX Nikons: D300 and D500.

Whichever dome I used (100mm or 8") I found I needed about an extra 20mm extension between the domeport and the housing to maintain the correct model point with the TC.

So with a 100mm dome port I use an EXR13 for just the Tokina. Add the TC and I need an EXR33. Similarly with an 8" dome its an EXR18 with just the Tokina. Add the TC and its an EXR40.

On shooting the humpbacks I wouldn't think there would be huge advantage in using the larger dome underwater. But then if they are near the surface and you end up shooting over/unders, the bigger dome is a huge advantage.

You are correct about changing the nodal point in relation to the dome's curvature. It is highly likely that you do need an extension.

Most housings seem to need around 18mm of extension with the 10-17mm and another 15mm of extension with the Kenko 1.4 TC. Of course, the amount does vary, so the only way to be sure is to try it out in the water.

There are a few manufacturers that offer specific extensions sized precisely for this lens.

In terms of domes, bigger is (nearly) always better in terms of IQ.

Adam

Thanks for the information.

Based on what I have and need, looks like I will be using the mini-dome for this trip.

I have the extension needed for it with the 1.4X but not for the 8" dome. My gear is a mix of Nexus with Nauticam housing due to past housings owned.

I posted a question regarding Back Button Focus in the Shooting Technique section. I hope you will answer there if you have help for my problem posted there.

Don't use the big dome without the proper extension, it will significantly degrade your image quality.

The advantage of big domes is that they give you better corner sharpness, especially with rectilinear wide-angle lenses. But this is not a high priority for shooting humpback whales, since there's no reef or detail in the corners of your shots.. it's all going to be blue water anyway.

And since you have to snorkel/swim to keep up with the whales and position yourself in the right place, the big dome is a significant disadvantage. It acts like a sail. You're much better off with the mini dome.

Finally, since the Tokina 10-17 can already zoom in quite a bit and humpback whales are big subjects, I don't really see the advantage of using a 1.4x teleconverter. It's only going to degrade your image quality and encourage you to zoom in to fill the frame when you should be swimming closer/waiting for the whale to swim closer instead. From everything I've heard, the water in the Silver Banks can be quite murky. Minimizing the amount of water between you and the whales should be your priority. You'll simply get better shots without the TC because it will force you to get closer to fill the frame with the whales.

Hey @TimG, do you have example photos of the D500 with the Posh Tok + 1.4x kenko? I'm playing around with medium sized subjects now (crabs/tompots) in the UK and I'm finding the most amount of success is with me being totally zoomed in at 17mm being SUPER close. But I feel I could get even closer to make it more dramatic.

My current issue is that it doesn't quite fill the frame with medium subjects, and I'm wondering if adding the teleconverter on a crop would:

1. Reduce image quality so much that I'm better off just cropping

2. Still make it appealing despite changing the focal length

I have a 20mm ext. ring + the mini dome (and mega dome) so I'm happy to experiment, and I guess the Kenko isn't all that expensive! But some example shots of CFWA with a crop camera + 1.4x kenko + tokina 10-17 at 17mm would be fantastic to help me out

Much appreciated.