gobiodon

16mm (wide angle) and flat port is the problem. This is the borderline and a dome port is recommended to avoid blured edges. You may try the 30mm macro lens. It's relatively cheap and will fit to your port (most probably)

I ordered endglow (less light loss) cables from here for other projects: https://www.lichtdekor.de/Lichtfasern-Endlicht/Lichtfasern-PMMA/ multiple fibers with coating: https://www.lichtdekor.de/Lichtfasern-Endlicht/Lichtfaser-in-der-Ummantelung/

It's a sideglow cable. Why don't you go for an endglow cable?

Why do you exclude the ikelite housing? It would support perfectly your strobes.

Competition is good: http://www.diyphotography.net/canon-bringing-modular-camera-system/

Great. Unfortunately wifi based wireless won't work underwater.

Sure, it's a specific tool but there are lots of good ultra-wide (weitwinkel) options in small size. I've just started to use Yi 4K and it's quite good, but I feel those action cams too wide. I've tried to implement some wide macro option to my gopro or yi but I haven't found any quality solution. Probably I won't buy the sony RX0, because it's too expensive, but I see many professional application (mainly multicam things) for this camera in underwater filming. For an amateur, like me, the Sealife DC2000 would be a better option.

"Does the $700 price tag include the 330ft housing?" I think not. I agree that it's a bit expensive.

Am I the only one who thinks that the new sony RX0 has tremendous potential as a small underwater video camera? http://wetpixel.com/articles/sony-unveils-the-rx0-action-cam I think it shouldn't be treated as an action cam and it's not a competitor of GoPro or Yi (and others) but due to the large sensor size and a non-fisheye lens it might be a great alternative small camera with a professional output. It was specifically developed for multi camera systems, so it might also be used to build a 3D system but it could be used as a pole cam. Adding macro filters looks possible and it makes sense due to the 24mm equivalent lens. What do you think? Cheers Marcell

I think symbiosis completely mimics the on-board flash of the camera, which has a pre-flash (for metering) and the main flash. I think you can't put your on-board small flash into complete manual mode (single flash) but I have to check. I don't have the camera with right now.

I don't have the symbiosis flahs but I assume the problem is that it reacts to the preflash and when the manual power is above a certain value it can't recharge for the second main burst that is actually involved in the picture. It's just a guess though. Can it work in a TTL mode? Best Marcell

I’ve been using an interesting lens combination for wide angle macro photography. I probably won’t use it underwater in the near future but I thought it could be interesting for the UW folks here. First I combined the sel30M35 macro lens with the fisheye adapter (VCL-ECF1) originally designed for the 16mm lens. It makes the angle of view much wider (around 15mm) but still keeps the macro capabilities of the lens including background blur. Photos have nice bokeh, quite different than a wide angle lens. Lighting can be complicated and you have to stop down a lot (minimum f16). I’ve written a blog post about it a while ago: http://fiberstrobe.blogspot.de/2014/08/sel30f35-vcl-ecf1-lens-combo.html You may also check some additional mantis photos on flickr, just to have an idea: https://www.flickr.com/photos/fiberstrobe/sets/72157646861145385 Recently I’m experimenting with the ultra wide (weitwinkel) adapter VCL-ECU1. It’s not that wide but easier to take photos and the bokeh is nicer. I’m not sure, which port could take this combo , since it’s long and it definitely needs a dome port. Nevertheless, I would be happy to see somebody trying this out also underwater. Cheers Marcell

Synching the 2nd optically??

In my blog I made a comparision of 30mm, 50mm and 100mm macro lenses taking the same subject at approx. the same magnification: http://fiberstrobe.blogspot.de/2014/09/put-sel30m35-lens-into-perspective.html You will see that the DOF is the same in all 3 cases (at given F number) but the perspective is completely different. Check especially the relationship with the background (not just the background blur and the field of view, but how the close subject behind the main one looks). They were taken not underwater but I hope it's helpful.

I'm not 100% sure but I think the TTL converter of Heinrichsweikamp should work. I guess the sony RX100 uses a similar simple flash protocol as my sony nex-5. I also have a meike housing and I use an ikelite strobe (51S) with their digital adapter. It works well. However, you will need a special cord with one end nikonos, the other end ikelite. You can find information about the converter here: http://www.heinrichsweikamp.com/?id=34&version=en Cheers Marcell