Adventurer

Looks like that is what they added to the the 2.0 version of the apollo S strobe.

I do not use Apollo S myself, but according to marelux the Apollo S 2.0 has two dedicated switch position on their left rotary dial called M-PRE and M. The M-PRE position should do what you are looking for and cancel out the preflash. M-PRE is supposed to fire out just one flash. They have this on their Apollo S and Apollo Y but not on my III 2.0.

Ehhhrmm,… which sony are you talking about? Your sony A6400 ? … should not be an issue with that one. Furthermore I am pretty sure all their Apollo strobes successfully handle pre-flash. If I wanted manual strobing on my Apollo III with preflash in my cam I will simply put it in MTL mode.

Very nice read @Alex_Mustard ! Given that Don Silcock tested the prototype for approximately one year, the official announcement was back in November 2025, and we are now in April 2026, it is a little disappointing that only one lens in the Nikon system still appears to work with Seacam’s OPP. That probably says something about both the technical complexity of this optic and the level of commercial demand for it. I really hope Seacam succeeds in expanding compatibility to more camera brands and, even more importantly, to a wider range of interesting lenses.

Very interesting Wolfgang, even though I am not a Sony User but this would supports the initial thesis of a very good air based „exit-glas“ (lens) bringing the right photons to the table 😉 Could you specify with a link which Sony 20-70 exactly you mean? Also interesting that you consider the 8-15mm a slightly less sharp performer. Have you ever used/tested WACP-1 oder WACP-2, Wolfgang and an impression on that one to compare?

I‘ll be bringing that setup to the water soon with the Canon RF 2.0x - I have also extensively shot the canon 8-15 with the Kenko 2.0x and love it. The IQ degradation is acceptable from the Kenko 2.0x as a trade for the enormous flexibility. That said, I always look forward into finding more optimized image quality gear. Special thanks also to @ChipBPhoto for sharing his extensive impression on WWL and WACP family. It confirms my impression that the only interesting candidate is the WACP-1 which comes at higher costs and weight. If you already operate an 8-15 Fisheye then the barrier to buy this is quite high as two good teleconverters will get you almost there as well. However I must gnarl that the Canon 2.0x TC is also a heavy beast compared to the Kenko 2.0x 😅 I think the best example for simple design and truly lightweight and absolute superior optic ist the old Nikonos 15mm (equivalent to 20mm prime). I wish we had more of that and an option to utilize it in the Canon RF mount system.

Very good points, Chris. Put differently, it is a bit like working with an upscaled image that is almost APS-C in size. Because you are using only the center of the optical system, the “corners” improve — although they are not really true corners anymore — much as they would if the photographer had simply cropped from the center of the image. So if one wanted to frame it positively, the credit for the improved corners and the straighter rendering arguably goes more to the air lens and its lens corrections than to the water-contact correction optic. 😉 The obvious downside, of course, is this: why take an expensive and bulky full-frame system underwater if you could achieve similar image quality with a more affordable and compact APS-C setup? Interesting - where did you find that? I’d really like to dig into those calculations.

Let’s not compare apples and oranges here and instead look at the genuinely relevant alternative to a 24–50mm paired with a wet optic (WACP-1, WACP-C, WACP-2, FCP, WWL-1 — or in your case, even the optically inferior WWL-C). What you are really referring to is the relative zoom factor of the Z-mount or RF-mount lens: 50 divided by 24 equals 2.08x, which we can reasonably simplify to 2x. A Nikon or Canon 8–15mm fisheye zoom gives you 15 divided by 8, which is 1.9x — so, again, effectively about 2x. My suggestion would be to pair that fisheye zoom with a high-quality 2.0x teleconverter, or even a 1.4x teleconverter. I am fairly sure you would end up with significantly better sharpness and overall image quality behind a dome than with any of the specialized underwater optics mentioned above. The image-quality penalty from a good teleconverter is minor compared with the gain in corner sharpness you get from using a strong lens behind even a small but perfectly positioned dome. On top of that, such a setup is far more travel-friendly and affordable than those bulky correction optics, and you do not need to “burp” it underwater. Last but not least, an 8–15 with a 2.0x teleconverter will project actual corners onto your full-frame sensor — no black corners. --> No hallucinated corner sharpness. This is exactly the kind of question I wanted this thread to examine. In the Canon case, for example: would you get a better optimized result with the current Canon RF 24–105mm IS STM, or with one of the two older EF lenses that Nauticam recommended for use with the early WACP in its 2018 catalog when used via the RF-EF adapter? Those two EF candidates were: Canon EF 28–70mm f/3.5–4.5 II (2.5x zoom ratio) Canon EF 28–80mm f/3.5–5.6 II (2.85x zoom ratio) At the time, the 28–70mm was Nauticam’s recommended option. But when you compare land-based tests of those lenses, both perform rather poorly compared with the center sharpness of even inexpensive modern RF glass. Lens design, manufacturing, and material science have improved to a degree that should not be underestimated in recent years. So the practical takeaway may be this: make the WACP work with the Canon RF 24–105mm IS STM, but discipline yourself not to use it at 24mm. Instead, use it consistently from 28mm onward, up to the maximum usable zoom range allowed by the front optic. That should give you more modern technology and, quite possibly, better overall results.

I have a problem with your generalized wording here. “In many cases” is not really specific. Furthermore, domes cannot be “nice” or “un-nice.” They are usually made of glass or acrylic, and both are perfectly fine and can do the job. When correctly matched and positioned, they can produce excellent image quality. However, I agree that many people and manufacturers have historically done a very poor job, which is why some dome-lens combinations have ended up with a bad reputation. But what really ticks me off is this: Underwater correction lenses (WACP-1, WACP-C, WACP-2, FCP, WWL-1) are sold to us mainly on the promise of improved corner sharpness — “x stops better than a dome.” They are then recommended by Nauticam, its ambassadors, and its dealers for use with these cheap kit lenses. But the 28–60 and 24–50 kit lenses in the new mirrorless systems do not project an image that fully covers a full-frame sensor at their widest settings. That does not magically change just because you put a $1,000 to $8,000 underwater correction optic in front of them. In underwater photography, this reminds me of The Emperor’s New Clothes: Nobody dares to tell the idiots that they have spent a ton of money on something that leaves them standing there naked. . Please take my crude verdict with some caution: for example, the WWL-1 enjoys an excellent reputation on Micro 4/3 and more compact systems, and for good reason. There, the sensor is smaller, so you do not run into these issues. The same applies to the above candidates on APS-C systems, where they can perform quite well too. But that is not what FULL-FRAME users can actually utilize or benefit from when spending a 4-digit sum on specialized underwater optics. .

This is wrong. The highly raved and recommended Sony 28-60 will not project corners @ 28mm on the image sensor and fakes this with digital lens corrections. Hence it cannot be as sharp (in the corners) as a lens that is not pitch black in this area. This was Initially complained about with the RF 24-50 Canon, but it’s not the only candidate suffering from black corners at the wide end. The Nikon 24-50 is likely to behave similar, though I have not RAW checked that one, yet. To me there seems to be a lot of bs out in the net, when underwater users of the Sony tell everybody how nicely sharp their 28-60 sony is paired with a water contact optic. It‘s true for the image center (but that’s with any lens) but not the corners on the wide end.

What makes a good underwater optic is, in my view, a different question and one that should be discussed separately. The Tokina 10–17 stands out for good reasons — mainly its fisheye design and extremely short minimum focusing distance. Those are exactly the kinds of criteria that should be used first to identify viable underwater candidates before weighing them against one another. But once you do that, the relevant comparison for the Tokina 10–17 fisheye zoom is the Canon 8–15 fisheye zoom. And in that comparison, the Canon wins on resolution and sharpness. At least in my experience, that advantage carries over underwater as well.

I have made this point in other threads before, although I cannot seem to find them now. As far as I remember, nobody ever seriously challenged my working thesis: “You cannot improve a lens’s in-air optical performance underwater.” What I mean by that is fairly simple: any optical system not originally designed specifically for underwater use — with the obvious exceptions of systems like the Nikonos 15mm and Nikonos RS — will suffer once taken underwater. Image quality will always degrade relative to that lens’s native performance in air. The moment we take a full-frame lens underwater and place it behind a flat port, dome, or a purpose-built underwater correction optic such as OPP, Ivanov, WACP, FCP, or Marelux Aquista, we are introducing a new front glass element into a lens design originally created by the optical engineers at Nikon, Sony, Canon, Sigma, and others. In other words, we are adding more “filter” to the light path. We are not performing magic. We are adding more glass. We are adding more interfaces. We are adding more opportunity for compromise. That does not mean such correction optics are pointless — quite the opposite. A lens may become far more useful, more practical, and more enjoyable underwater when paired with the right optic. But it will not suddenly become sharper, cleaner, or more transmissive than what the best land-based lab tests already show it to be capable of in air. What it can do is perform vastly better in its actual underwater use case when paired with the correct optic, especially when compared with the same lens behind a flat port or a poorly positioned dome. So when people speak as though a port or correction optic somehow improves a lens beyond its native land performance, I think that is where the language becomes sloppy. Better underwater than with the wrong setup? Absolutely. Better than its in-air optical ceiling? I do not see how. So I am putting this out here for discussion and, ideally, confirmation or informed contradiction. My working assumption has long been that the best way to identify a strong underwater optical system is to start by comparing land-based tests of lenses that already fit key underwater criteria — for example, short minimum focusing distance and other relevant characteristics — and then distill the strongest in-air candidate before bringing it underwater and matching it with the most suitable port or correction optic. That, to me, seems to be the real algorithm: start with the best land candidate, then optimize the underwater setup as intelligently as possible.

@Alex_Mustard was allowed a test drive in Raja Ampat with this lens and shares his experience on the show:

I recently looked at a Sony 28–60mm RAW file and was surprised to find that this lens also relies heavily on lens corrections and produces completely black corners on a full-frame sensor. I had always thought this kit lens was somewhat “holy” because it has a strong reputation for delivering very sharp corners, especially among underwater shooters using it with Nauticam water-contact correction optics.

You’re right — sorry. I got a bit carried away. That said, I’d genuinely like to hear more thoughts on strobe design philosophy from people who owned the Retra Pro Max II and then moved to the Maxi. Did anyone here make that switch? If so: what did you feel you sacrificed (if anything), and what did you gain? More broadly, do you think the future of strobes is primarily Li-ion (18650 / 21700) — and that dual-AA designs will slowly phase out? For my own journey (INON S-220 -> Apollo III 2.0 -> Backscatter HF-1), it’s a bit like driving a good electric car: once you’ve experienced the convenience, it’s hard to go back. The ability to shoot most of a dive day — sometimes multiple days — without opening the battery compartment is a genuinely pleasant experience. Just to put some numbers on “stamina” (manufacturer-rated flashes; conditions obviously vary), here’s what I’ve found listed at/near full power: Retra Pro Max II: 300 flashes Backscatter HF-1: 375 flashes (BOOST +2) INON S-220: 500 flashes (FULL)* Retra Maxi: 550 flashes (FULL) Apollo III 2.0: 800 flashes (FULL M) * Reality check from my dives: I still swap batteries in my INON S-220 before a third dive if I don’t want to risk running out during that dive. So the 500 flashes on the INON maybe archived in a lab type test but in practical diving I feel it lasts substantially less than the new 21700/18650 strobes. With Li-ion strobes, I can often shoot for several days without changing batteries. Working theory: part of the difference might be standby consumption during the dive (keeping the capacitors topped up / ready between flashes). If that’s true, the higher-capacity 18650/21700 designs could have a real advantage here.