My first underwater test of the Sigma 15mm Fisheye behind the Zen 4″ Fisheye Dome Port on the

Finally after successfully cutting off an amount of the shade on my brand new 15mm Sigma Fisheye lens I have managed to get it behind the Zen 4″/100mm fisheye mini dome port and get it in the water. The reason why I wanted to do this was so that I could take CFWA (Close Focus Wide Angle Photography) on a full frame underwater camera system. The Zen 4″ is an awesome piece of gear and although it does come with a hefty price tag, the workmanship and quality makes it worth every single dollar – I bought mine from Backscatter.

Keeping it simple – to achieve CFWA you need to find a nice fisheye lens that allows you to focus very close to your subject. Unlike larger dome port, the distance from the front of the lens to your subject is a lot shorter when using the Zen 4″ mini dome port, therefore allowing you to focus closer in on those small subjects which can allow you to achieve a pleasing photograph. Up until now, the most common lens that works perfectly with the Zen 4″, is either the Tokina 10-17mm or the Nikkor 10.5mm. With both of these lens not being suitable for a full frame camera, the Sigma 15mm fisheye with its very close focusing abilities, seemed the obvious choice. Sadly out of the box, the metal shade to this lens hits the inside of the port preventing you from fixing it to the camera housing. With this in mind, there are not many people out there willing to risk buying and chopping up a new lens to just see if it works behind the Zen mini dome and so I have found information about this set up very limiting.

Having a full frame Nikon D3s, I really wanted to give it a try as I believe the results will be great from this camera and so I took the risk of cutting down a brand new Sigma lens and buying the Zen 4″/100mm Fisheye Mini Dome. The following is the first of three tests to see if Sigma full frame 15mm Fisheye lens works behind the Zen 4″ dome port on the Subal ND3 with the Nikon D3s. The goal of this first pool test was just to see if the lens focused properly and just how sharp my initial test shots could be. I am quite pleased with these initial results although the next test will more focus on corner and subject sharpness from f2.5 through to f22.

The following photographs have not been sharpened – click to enlarge.