Zen 100mm and Nauticam for Canon 7D

I just purchased the Zen 100mm (4") dome for my Nauticam NA-7D and Tokina 10-17. What's the consensus on the need to use an extension with this configuration or can I use it without one?

I took a couple of above water test shots with no extension and they look pretty good. Does adding an extension make the corners even sharper?

Advice would be appreciated.

hi Andy

The 4" dome should be alright without the extension ring for the 7D. It is pretty sharp at 180 deg angle of view. I think you could have read something about this lens with full frame cameras hence the slight confusion.

The tokina 10-17mm could also be used with FX or full frame 35mm sensors like the 5D with a Kenko 1.4X teleconverter and that would require a 20mm extender otherwise it will vignette. Tokina also make a hoodless version of the 10-17mm that could be used without the extender. Ie. closer to the mini dome. The effect is like the 8-15mm Canon FE F2.8. On full frame the widest is almost a full circle in a black rectangle and from 14 to 17mm very wide angle but not 180 deg. Anyway your 7D is APS-c so the lens is made for this format. You might see cut-offs if you use an extension ring at the widest.

Cheers

David

Hi Andy,

If you purchased a new Zen 100mm dome you are fine and won't need to add a extension for your 7D. The original Zen domes were shorter and required a 20mm ext for the 10-17. So if you bought it used you might need to add the 20mm. You will have a blast with this setup. There are thousands of amazing images out there just waiting for you to make them.

Cheers,

Steve

Thanks David and Steve for your responses. It's a new Zen dome and I'll be taking it with me to Lembeh next month. Looking forward to adding some CFWA images to my portfolio!