Adventurer

Good news everybody! The lens has already made it to optical bench hub: https://www.photonstophotos.net/GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/US20260029629_Example06P.txt,figureOpacity=0.25,AxisO,OffAxis Two some very good indicators that suggest it to be a good uw candidate: 1.) Entrance Pupil just moves 4.35 mm during zoom 2.) Just 42mm front glas diameter (will work with many water corrective optics) 3.) Minimum subject distance in Front of the lens = 123,2 mm = 12,32 cm 94° diagonal FOV @ 20mm behind a dome

Here is how I would rank it, IQ sharpness wise: 1.) RF 24-105 STM (the sharpest!) 2.) Canon EF 8-15mm with original EF-RF Adapter 3.) Canon EF 8-15mm with comlite EF-RF Adapter (I have not shot this combination, as the comlite seems to exhibit some dismal AF performance compared to the Camon EF-RF adapter already on land) - so this is a „I suppose“ line 4.) Canon Fisheye 8-15 with original Canon RF-EF adapter and Kenko 2.0x TC 5.) Canon Fisheye 8-15 with modified Comlite RF-EF adapter and Canon RF 2.0x TC

I am happy Canon made this lens. 20mm is the sweet spot before rectilinear lenses start looking odd. I hope the lens design pops up on optical bench soon, so we can have a closer look.

Having done a few more snaps in the field and tightly comparing the sharpness of my lens line-up, I must conclude: Newer RF lenses are more razor (sharp) than older EF lenses. This basically confirms also various land based tests I churned through on the internet. Surprisingly my RF 24-105 STM is the sharpest lens in my lineup and it outperforms the EF 8-15 fisheye in overall IQ sharpness on average. I even think the RF 24-105 is sharper than the Canon RF 100 mm macro behind a flat port on many occasions. Also I am currently under the impression that the EF 8-15 combined with the Kenko 2.0x PRO TC performs better than with the RF 2.0x comlite adapter.

@TimG my condolences! What a nightmare. I hope you are not too traumatized by the experience and the gear loss aftermath.

So you made the jump to new strobes @waso … were you already able to take them out for a test drive ? … interested to see your first results with them soon.

Similar complaints from my better half here, too. She usually says something like: „Oh nooo, are you going to watch Shrek again,… ?“ before she leaves the room. 😅 🥴

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.