5 hours ago, Chris Ross said:

There are a number of constraints when using lenses behind water contact optics, there is an entrance pupil constraint and there are also issues with zoom lenses that change length as they zoom

I looked into using the z24/1.8 with the wwl-c a while ago and this was the issue. Front element cause vignetting.

Edited Friday at 07:45 AM2 days by Christian K

3 minutes ago, Christian K said:

I looked into using the z24/1.8 with the wwl-c a while ago and this was the issue. Front element cause vignetting.

Yes, it's unclear exactly what sets this and it varies between the WWL and WACP models as to which lenses they work with. I would guess that port charts for these optics are fairly complete and to get a better optic use the chart to help, but probably involves going to a WACP. I would think that the main limitation with some of these bigger lenses is the flat port size (port ID or the m67 port diameter causing vignetting), or some of the small primes a short enough port to properly accommodate them.

9 hours ago, Chris Ross said:

The other advantage of the wet optics is that shooting at f5.6-8 is possible where the corners would be pretty mushy on a rectilinear behind a dome.

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?

Looking at the WACP - calculations show that this is closest to a stereographic projection fisheye,

Interesting - where did you find that? I’d really like to dig into those calculations.

Edited Friday at 02:58 PM2 days by Adventurer

7 hours ago, Chris Ross said:

Yes, it's unclear exactly what sets this and it varies between the WWL and WACP models as to which lenses they work with. I would guess that port charts for these optics are fairly complete and to get a better optic use the chart to help, but probably involves going to a WACP. I would think that the main limitation with some of these bigger lenses is the flat port size (port ID or the m67 port diameter causing vignetting), or some of the small primes a short enough port to properly accommodate them.

Yeah, I’m not sure the WACP route will yield any gains that are really worth it for me compared to the WWL. Maybe if I start shooting at home in the Baltic Sea regularly… that does not involve flights.

As an owner of a WACP-1, WACP-C, WWL-1B, and Canon 8-15, here is my objective, real-world experience with all. I use the inexpensive Sony 28-60 in all cases except the 8-15 for ultra-wide scenes.

Note 1 - One of the greatest strengths of all the wet optics is the inclusion of a real zoom option.

Note 2 - All water contact optics have a slight degree of barrel distortion at the wide end. Scenes such as pier legs or wreck interiors are best when zoomed in a bit to help compensate, or correct slightly in post. This is not, however, noticeable in normal reef scenes even at the widest FoV.

WACP-1: Dry Port - no water layer between the lens and external dome.

- Large on the surface with a weight of 10lbs dry

- Best image quality of the three, but not overly noticeable unless comparing side by side with others

- Very stable in-water due to size; beneficial for slower shutter or video work

WACP-C: Dry port

- Smaller version of the WACP-1 weighing only 5lbs dry, or half as much

- Not quite as sharp, but only noticeable if compared at high zoom in image review side by side with the same from a WACP-1

- Substantially lower price in comparison

WWL-1B: Wet Mount Port - layer of water between the flat port and the attached WWL.

- By far the smallest and lightest of the 3

- Very similar image quality to the WACP-C.

- My go-to choice for travel when size/weight are issues

- The lowest overall cost

- Must “burp” lens after entry to make sure no air bubbles are trapped between port and wet lens

- *WWL-C is same concept except designed for 24mm lenses vs 28mm

Canon 8-15 w traditional hemispherical dome

- Go-to fisheye option for exceptional quality

- Ultra-wide 180 FoV vs 130 degree max

- No real zoom ability

- Easily used with a 1.4x teleconverter for greater reach with no noticeable image degradation

Does the addition of a water-contact optics improve the quality of a standard kit lens?

In my actual use and real-world comparisons…yes.

I find the corners to be sharper at a wider aperture. This provides great flexibility when lower light becomes an issue

Is this better than a traditional lens and dome? That’s really personal taste, very similar to how much salt to add to food. “Better image quality” is open to interpretation. With regards to overall user experience, I personally feel there are greater options to capture a moment, especially in fast-action scenes with the water contact optics.

Can I prove any of this with scientific numbers?

Nope, that’s not my forte.

These are simply my personal finds and my personal preferences. Plenty will have other opinions and/or thoughts, and that’s great too. That’s why there are many options so all preferences can be met.

Paraphrasing Ansel Adams, the image is made 12” behind the lens. In other words, it’s not the gear, it’s the photographer that makes the image.

Above all, dive and enjoy capturing the moment!

Edited 9 hours ago9 hr by ChipBPhoto

On 4/16/2026 at 3:39 AM, Adventurer said:

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.

Two corrections to your above statements;

1. I never need to "burp" my WACP
2. Traveling with a WWL is significantly easier than traveling with a medium or large dome.

Edited 9 hours ago9 hr by OneYellowTang

Today I shot the Nikon 8-15 fisheye + 1.4tc (old kenko) behind a 140mm dome using a 3d printed 40mm port extension and custom zoom gear. I think it worked very well. The "full" field seems to be at 12mm. A few shots were at 11mm and have very slight clipping.

Nikon Z8 with Retra Maxi strobes

12mm full field shots:

15mm "bonus 1.4x zoom" shot:

Edited 22 minutes ago22 min by Dave_Hicks