Nexus D100 / Sigma 10-20mm /230mm Port + 40mm EXR

Hi,

I just got a used 230mm FP port for my Nexus. It's quite large and works best for over - under shots. To use it diving, I will have to add some counterweight. Am planning to use the above combination. Does anyone know if it will work? Will the Nikon 17-35mm zoom ring work?

Thanks,

Chad

Just going by Nikon & Sigma webpage specs. Sigma 10-20 is 3.3"dia x 3.2" long. Nikon 17-35 is 3.2" dia x 4.2" long. So 17-35 gear probably will be too small for Sigma. The extension ring size will depend on the location of the lens nodal point (which will vary when you zoom in/out). The Sigma is close to the Nikon 12-24 in length, so the nodal point might be in the same general location (I'm guessing here). Going off recent tests with other domes & 12-24 lens as reference, a 20-40mm ring should be close. You really need to test your setup to find out for sure. It in part depends on whether the 230 is a true hemisphere. My 170 dome is not a complete hemi. The center of curvature is 20mm behind the base ring. Nothing is easy. The 10-20 should be a neat setup - just need to fine tune. Maybe someone else is using it & knows for sure. These WA zooms definitely need a large dome. I almost have the 12-24 working with the Nexus special 12-24 dome, but with a +4 diopter on lens & 30mm ring. 20mm ring might work better thou - 30mm has vignette at the wide end but corners are sharp. Not claiming to be an expert on this stuff - just sharing my recent experiences.

The 230mm dome has length of 93.4mm. Which means the center is also 20mm behind the base ring. However, with a larger dome, would it mean that the angle of coverage should be wider? So would it mean that a shorter extension ring would reduce chances of vignetting? Anyone using the FP230 dome?

I read in a prior post about being able to use the Sigma 17-35 ring on the 10-20, but that was for an Aquatica setup. I wonder if Nexus makes one for the Sigma 17-35.

Thanks,

Chad

The 17-55 gear may work...I think it is around 3.4" and a little extra shimming with Nexus rubber grippy thingies that fit into groves under gears may be all you need. I would contact one of the sponsors here (marine camera or woody at nexusamerica).

M.

17-35 Zoom Gear fits perfectly.

I have customers using the lens w/ a 40mm extension in the Athena 170mm glass dome who are getting great results, with or without a +2 diopter.

Ryan,

That's great news! Will try the setup in a couple of weeks. Thanks.

Chad

Hi folks,

I finally got the 10-20mm and ordered the 17-35 zoom gear. And fits perfectly as Ryan mentions. I just take out the rubber ring inside the gear and I don't need to take off the rubber grip from the lens. It's a tight fit, and the gear almost rides at the edge of the lens zoom ring, covering the zoom length numbers. In the housing, the wheel is smooth and turns without problem. Zooming from 10 to 20, the lens barely extends out at all. Looks like around a 1 cm of extension.

With the 230mm port, my results in the pool seem quite well, corners look sharp, (but who am I to judge... ). It focuses about 1 inch off the dome surface.

Just a question. How do I know if I need a dipoter or not?

Will be testing in the sea tomorrow. Hope to post some of my results so the experts here can help with any comments or adjustments I need to make before I go on my liveaboard trip.

Thanks,

Chad