i have the sigma 15 which can supposedly be used with the metabones as well but then theres the issue if that combo fits in any existing ports. i assume theres a way to do it, but ideally it'd fit in a mini dome. For example, the sigma 15 fits in the zen 4" mini dome if you shave the lens shades, but is that dome compatible with nauticam housings for sony mirror less?
Matt. Are you talking about full frame or APS-C Sony mirrorless? Nauticam have 3 different size port systems that could provide a solution for you. N85 for the APS-C NEX/A6000 series, N100 for the Sony A7 series and N120 for conventional DSLRs. I know the ZEN 4" mini dome is available for Nauticam N120 - I own one. And Nauticam make N85 to N120 and N100 to N120 adapters. So with one of these adapters you would just need to work out the best port extension to position the lens optimally in the dome. I don't know if ZEN make their 4" mini dome in the smaller Nauticam port sizes so that an adapter is not required, but Nauticam themselves supply an acrylic 4.33" dome with N85 fitting.
If you are considering using the Sigma 15 / metabones with a cropped sensor Sony mirrorless, you will of course loose much of the fisheye effect and angle of view so I'm not sure the exercise would be worthwhile - you might do as well sticking with a rectilinear UWA lens.
The reason for using the ZEN 170mm dome as opposed to a mini dome with the Tokina 10-17 is the versatility of the 170 dome - it can also be used with the rectilinear E mount Sony 10-18 and Sony Zeiss 16-70 zoom, the latter making a good mid-range zoom for larger or skittish subjects. The edge focus performance is better than the mini dome but the penalty is slightly less close focus for CFWA.
I don't understand why sony hasn't put out an e mount actual fisheye lens. instead they have the fisheye converters for the 16mm pancake lens which has gotten a lot of negative reviews, and then the fisheye converter for the 28mm. Wouldn't it make sense for them to put out something similar to the panasonic 8mm fisheye? a small size dedicated fisheye lens (hopefully not quite 8mm wide) would be a pretty sweet addition to the lineup and would guarantee an investment by me in sony gear for UW.
thoughts? i like the zeiss 12 and 24 as well but they don't fit the small mini domes from what i can tell
I agree with this. Even if the FE 28mm/fisheye combination turns out to be optically good, for cropped sensor users (NEX/A6000) the reduced angle of view will negate much of the perspective advantages of fisheye underwater. We have partially solved this gap in the Sony range by using a Nikon mount Tokina 10-17 fisheye with a Novoflex Nik/NEX adapter. Fixed aperture and focal length when in a housing and manual focus using peaking with a custom gear behind a Zen 170mm dome. The optical results look very satisfactory and for fisheye, lack of aperture and zoom control underwater is perhaps an acceptable price to be paid for good optics and perspective?
The alternative untested combination of Canon mount Tokina 10-17 and Metabones Canon/NEX adapter might offer aperture control in addition.
If I read you correctly, you're running the 1670Z with the same adapter and domeport than Zen sells for the 12mm Zeiss - right?
Not quite - same glass but different mount. This is the Zen DP170-N85-II. This is the 170mm dome for Nauticam m4/3 and Sony NEX systems with a built in 30mm extension. No adapter or further extension is needed with the 1670Z. Phil Rudin started an extensive thread on this dome within this forum.
does the 1670Z focus at every zoom length without a diopter?
Almost certainly yes. The 1 week trip we used these combinations on was primarily wide-angle, so we used the 1670Z for only one dive with pelagics, and as such it was probably used mostly towards the long end of the zoom range. We didn't methodically check at the 16 end. However Nauticam support this lens with their own acrylic 170mm port without need for a diopter and this is equivalent to the glass DP170. I also checked with Ryan Canon from Reef Photo / Zen before purchasing and he confirmed compatibility of the 1670Z without diopter.
How did you fit the zoom gear through the Zen step-up adapter - or do you already have the new one with 77mm inside diameter? Or are you using some kind of Nauticam adapter to the Zen dome?
The beauty of this version of the DP170 is that it doesn't need a step up adapter, and with the 1670Z it doesn't need an additional extension. There is therefore plenty of space for the 1670Z zoom gear.
When it came to using the Tokina 10-17 fisheye with Novoflex Nikon/NEX adapter, space was much tighter when an additional 30mm port extension was added. However there was still just sufficient space to design a custom gear that passed over the Tok barrel with rubber grips removed but still provided clearance within the port extension.