DreiFish

A further price drop -- willing to sell the entire package for $600/strobe or $1300 for everything.

Indeed, seems Retra pushed the flash tubes (I imagine they're the same as used in the YS-D3 and Backscatter HF-1) just slightly further, and put a slightly brighter, slightly better CRI video light on there. Still, can't complain about the end result -- if you're in the market for the Backscatter HF-1s, you should also seriously consider the Retra Maxi, since price is very similar and Retra arguably has a better range of accessories atm and build quality. What I especially like is the even higher battery capacity (550 full power flashes vs. 375 on the HF-1); the even faster recycling times (claimed 50fps vs 30fps -- though how that translates in practice to more practical 1-10fps shooting speeds remains to be seen), and, most importantly, same weight and similar size with better boyancy characteristics (only -20g negative). Plus, better controls. If cross-shopping, I guess it comes down to how interesting/important the Backscatter HF-1s ambient light filters are to you and which strobe has a better TTL implementation -- though those are really niche features for most. Excited to try them..

Hmm... on first glance, it seems to be a Retra version of the Backscatter HF-1.... Does it use one straight flash tube, or two? The claimed GN of 46 seems a bit high for a single flash tube strobe. Any information on recycling times or Watt-seconds?

Unfortunately, you're running into limitations of physics here, because of the way dome ports produce a curved virtual image, which is what your lens is focusing on/filming. On an APS-C sized sensor, that means you really can't be below F8, and F11 is probably better in order to get reasonably sharp corners. The only things that can help are a larger dome or shooting at less wide focal length. Things start to improve around 20mm (FF equivalent) and get pretty good by 24-35 mm. But if you want to shoot at 11mm (16mm FF equivalent), you need both a large dome (230mm preferred) and narrow apertures in the F8-F11 range. Getting a different lens might improve things slightly, but the issue is that the center of the image and the corners are at different focal length because of the curvature of the virtual image created inside the dome. Lens quality can't solve that. Only a larger dome or a narrower aperture can. Since the Blackmagic camera is also ISO limited.. you basically either have to bring a lot of artificial light into the scene or look into wet contact optics like the Nauticam WACP-1 or WACP-2

Detailed review from Gerald Undone: + Dynamic range is class-leading in video (13.5 stops), better than A1 (12.9 stops) - Still no easy way to set white balance...

Price drop to $800/strobe and $200 for the trigger. $1500 for everything.

That's not vignetting -- you're just using it wider than intended, so you're part of the way towards the circular fisheye, just not all the way there. It's the exact same effect you would have if using it without a TC on full frame wider than 15mm...

No direct experience, but Hawaiian waters are generally pretty clear, blue water territory. I'd start experimenting with the flat 5500k or flat 4500k diffusers, those are probably your best bet.

Hey Adventurer, That's what I was hinting to above that once you get to extreme retrilinear wide angle focal lengths, you start having to deal with extreme pincushion perspective distortion near the edges and corners of the image. This is a function of the focal length, and completely separate from the optical quality of the lens and how sharp it is at the edges or in the corners. I tend to agree with you that the perspective distortion can make it a hard lens to shoot underwater, especially if you're used to the barrel distortion that fisheye lenses (and Nauticam's wet wide angle optics) produce. It just.. doesn't look right, and objects near the edges get stretched in aesthetically unpleasant ways. This is definitely an issue at 14mm, and exponentially worse at 10mm. It's basically gone by 20mm, so I'd say it's easier to deal with in the 16-20mm range. But of course, then you trade off field of view and how close you can get to the subject. Which I guess ultimately is why lenses with barrel distortion like fisheyes and nauticam's wet wide optics may be a better choice for the majority of underwater wide angle shots where straight lines aren't an absolute must. You can get pleasing images with extreme wide rectilinear lenses. I posted some at 14mm in this thread: But.. it's generally harder to do so. At least for those of us used to shooting and seeing typical wide angle scenes with barrel distortion compressing the edges. For versatility, I still think the fisheye (or a fisheye zoom) should be your first choice for underwater wide angle stills. Followed by Nauticam's wet wide angle optics like the WWL-1, WACP-1 and WACP-2. Then a rectilinear zoom in the 16-35mm range (if it goes wider to 14 or 15mm it's a bonus, but you might not end up using the wider end too often). Only then should you consider rectilieanear lenses in the 10-14mm range for specific shots. But they're not really general use lenses in my view. You run into the same extreme pincushion distortion at the edges when shooting video also. Any sort of camera movement will accentuate the pincushion distortion near the edges, distorting any objects that enter the edges of your shot. If anything, it's harder to compose your shot to hide/minimize the pincushion distortion at the edges with video than it is with stills. This is why many people seem to prefer the Nauticam wet contact optics like the WWL-1 or WACP-1 for video, since their mild barrel distortion at the edges produces a more natural and organic result with video than either a fisheye or wide rectilinear lens. If using rectilinear lenses, again, the issue resolves itself at tighter focal lengths obove 18-20mm. You may even get away with 16mm with careful composition. But I at least haven't personally seen any great examples of underwater video filmed with rectilinear lenses wider than 16mm. If you have, please post links!. For further discussion about the use of extreme wide angle -- fisheye and rectilinear focal lengths with video, see this thread: )

You're right, other housing manufacturers have a shorter lens mount to front of housing flange distance (and for Marelux, wider inner port mount diameter, 125mm instead of 120mm) on their full frame Canon RF housings. This offers a few more choices in terms of getting the optimal lens placement without vignetting. I have no doubt that you can get the RF16mm prime to perform optically better with no extension / 10mm extension on Marelux housings, which I believe are about 20mm shallower in depth than the Nauticam n120 RF housings. You also can achieve less vignetting with wider 10mm lenses I believe). Whether that placement flexibility significantly improves the optical performance of the RF16 prime behind a 140mm or 230mm dome compared to what can achieved on Nauticam n120 housings is a separate empirical question -- I don't know. Perhaps with the right extension, the RF16 will actually perform better optically than the RF 14-35L or 15-30 or 10-20L lenses. It would give you a very small package with the 140mm dome. But.. of course, the tradeoff will still be zoom versatility, which is a significant tradeoff to have. I really don't think the RF16mm swings the balance towards Canon when comparing Canon RF vs. Sony FE full-frame systems for underwater wide-angle use. Sony has unique prime wide angle options too, like the 14F1.8 GM lens and the Laowa 10mm autofocus prime.

Hey Adventurer, No, the 8-15 + 1.4x (or 2x for that matter) doesn't vignette by itself. Of course, you need to have the right extensions for your dome port.. shorter extension may somewhat vignette, but that's a function of the port and extensions, not the lens and TC. The Canon FE Zoom is one of the best wide angle options on both Canon and Sony full frame systems. Also for their crop bodies. And it works great (with no TC or with a focal reducer) on M4/3 systems as well.

Hi Adventurer, I have compared the RF 14-35L vs the RF 15-30 and RF 10-20L lenses. Thread here: The 15-30 is marginally sharper than the 14-35, but it's a pretty minor difference. The RF 10-20 is actually better than both of them at 14 and 15mm. But it's certainly not a night and day difference, and many may still prefer the 14-35mm for the greater zoom range. As for the 16mm.. I have to disagree. I've also tested this combination, and the real issue is that it needs a negative extension of about 20mm on N120 to put the entry pupil at the center of the dome. Comparing it directly with the RF 14-35mm at 16mm, the 16mm prime isn't really any sharper (but it's not worse either). Maybe just marginally better than the RF14-35 in the corners. Finally, while the 8-15mm fisheye + 2x TC gives you a nice zoom range, there's definitely a noticeable image quality degradation and loss of light transmission, and worse autofocus. But at the end of the day, I think Sony still offers a better solution for using the 8-15mm Canon fisheye with a metabones adapter and the Sony 2x TC, which is optically superior to the Kenko 2x TC. Maybe the autofocus is slightly more finicky, but it's still usable (you don't need much from the AF system when shooting this wide).

Thanks Alex, that's very helpful. Totally agree that recycling times are not that relevant in general underwater wide angle shooting. They're probably only interesting for fast action pelagic shooting, and perhaps not that important there either if once a strobe can take 3-5 frames a second.

By all accounts the Ef 8-15 fisheye works great on sony's latest cameras with an adapter. I've used it before with the Sony A7RII and it was more than adequate for wide angle photos. So.. I don't think the native fisheye argument holds much water. You can use the same lens with Sony cameras and metabones adapter just fine, and many people do. Aditionally, there is a conversion available to use the Nikonos 13 fisheye as a 'native' Sony lens, which is not an option with Canon currently. So on balance, for wide angle photography, if fisheye is your thing, I still think Sony system offers more options. You also can theoretically use the new Sigma 15mm F1.4 fisheye lens natively on Sony, though I haven't heard of anyone trying that underwater yet. Also, if you want the EF 8-15 + 2xTC, you can do that on Sony with either the Kenko EF 2x TC or the higher quality Sony FE 2x TC. With Canon, you can't use the RF 2x TC, only the Kenko. Now when it comes to Nauticam optics, it's a hard call. Sony system has better lenses that can be used with the WWL-1B, WACP-C and WACP-1. Canon has the 14-35 and 15-35 for use with the WACP-2. With Sony, you can use the 16-35 GM II with the WACP-2, which is a slightly sharper lens than either the RF 14-35 or 15-35, but you do only get 128 degrees diagonal at the wide end vs. 140 degrees with the 14mm. But even there, there is the Sony 14mm F1.8 GM prime that probably gets you better overall IQ than any of the zoom lenses, and also the Sigma 14mm F1.4 Art lens. So what the Sony system loses with the WACP-2 is perhaps a bit of zoom versatility, but not image quality to Canon. Nauticam FCP also favors Sony on balance. You can use it with the Sony 28-60 and the newer 24-50F2.8 G lens. Plus the 14mmF1.8 prime for circular fisheye. With Canon, if you want to use the full zoom range, you're stuck with either the 24-50F4-6.3 lens which is a pretty unimpressive kit lens, or the (quite old) EF 28-70F3.5-F4.5 zoom, which is a touch sharper, but still not great. Your best option for image quality might be the RF 14-35 which gets you both a circular fisheye at 14mm and limited fisheye zoom between 28-35mm. But then it's only a 170 to 122 degree zoom range, similar to the 8-15mm fisheye + 1.4x TC. When it comes to lenses behind a dome.. you get a auto-focus capable Laowa 10mm (which is sharper and can be used with a smaller dome (140mm dome) than the Canon RF 10-20mm (needs 230mm dome) -- I've tested both). You also get the 16-35 F2.8 GM II and new 16-25F2.8 G lenses, which are as good as any zoom lens on Canon and (unlike the Canon options) can perform well with a 180mm dome. So perhaps less pronounced an advantage for Sony lens selection when it comes to rectilinear lenses behind a dome, but if size enters the equation, the advantage is big -- none of the Canon rectilinear prime options work well with anything less than a 230mm dome. Wholistically, I'd argue that the lens selection on Sony is a bit better than currently with Canon for underwater use when it comes to wide angle. Macro is a more balanced picture with some wins for Canon.

Shorter flash duration is better (i.e. the flash outputs all the power it's capable of outputting in a shorter window). If the flash duration is faster than the shutter speed you're using (which is limited by your camera's flash sync speed), then you will capture the full illumination the strobe is capable of on the sensor. Conversely, if you set a shutter speed shorter than the flash duration, say, 1/200s and the flash requires 1/100s to output a full burst, then you'll only capture part of the illumination. Generally, it's not an issue as most flashes are at least 1/300s or faster, and most cameras have flash sync speeds slower than 1/300s. So.. you'll always get the full flash output. The only exception I know of is the Ikelite DS230, which is slow, and needs a full 1/100s to output full power. That means at many common shutter speeds used for underwater photography, you can't take advantage of the full power of the flash. HSS works differently than a full burst. It fires a series of short bursts (at lower power) in quick succession, which is necessary in order to match the falling curtain of the camera's shutter as it travels across the frame if shooting at shutter speeds higher than the camera's native flash sync speed. Because of this, a flash in HSS mode will output less overall light then the same flash fired normally. Flash sync speed and HSS capacity are not really related I don't think, though it's reasonable to conclude a flash with a faster flash duration should be able to output comparatively more light in HSS mode than a flash with a longer flash duration. The Ikelite DS230s for example don't have an HSS mode, but if they did, it would probably not be great because the flash tube needs to be 'lit' for a long time (comparatively) to output its full power and probably can only output a small fraction of that power during the shorter times needed to implement HSS.