In short - sometimes...

For comparison first I am bringing 2 images shot on the same location (Carnatic shipwreck at Abu Nuhas, Red Sea) 1 year apart shot using WWL-1B and adapted canon's 8-15 (no TC). I would say it even may be the same corral just shot from different side.

First WWL-1B from 2024

300% central part

and 300% kind of out of center to show depth of field

And kind of extreme corner lower right

Now the same for 8-15 at 15mm F10

center

off center with background

and the corner lower right

You can clearly see that 8-15 significantly outperforms WWL/28-60 on subjects sharpness, micro contrast and overall rendering. Where WWL excels is a uniform unsharpness 🙈 across the frame and much greater perceptual depth of field for entire image viewed on a small device.

And it's kind of logical. Nauticams wet optics (WWL, WACPs, FCP) final results on Sony (do not know canons and nikons lenses) are held back by poorly performing 28-60 which - compared to canons 8-15 - is soft and especially on tight end with relatively poor micro contrast and overall rendering. On the other end if one doesn't plan to crop heavily or print large HD prints then it doesn't matter that much and this expensive wet optics will produce nice postcard size images🙈.

Fisheye on the other hand will produce much greater field of view which also means that one has to get much closer to the subject for meaningful impact which means that one needs to select the scene very carefully otherwise only central piece of image is going to be in focus and the rest will be a mess. Especially for concave scenes (like small caves where subject is in the middle in the back - see pictures below) the use of this fisheye lens would be less then ideal. Basically for CFWA shots like clownfish anemone sunburst it's like 1:10 you could get into a good position while with wet optics much less.

These results are not surprising as for DOF and are in line with dome theory and wet optics theory. Simply said with fisheye you need to be so close to the subject that you effectively focus at minimum focus distance for lens while hyperfocal would be much further away. With all DOF implications. For subject-less scenes 3m away this would be different but for smaller subjects you need to get real close.

I have had TC2x only on first dive and at first glance I didn't like the results so I skipped using it - perhaps prematurely judging from anemone detail taken at 30mm... oh well. And also this is an example of that wrong scene for fisheye lens.

So 8-15 TC2x at 15mm

the same scene at 30mm

and 300% crop

So this is my experience with adapted 8-15 which except for autofocus misses fulfilled my overall expectations even though it brought different set of challenges. And lastly following image shows example of a neutrally buoyant configuration - 140mm glass dome + 35 + 20 + 8-15 + Metabones + Sony TC2x + A1 + Shinobi (NPF970 battery) + Retra Pro X with superchargers

Interesting writeup, thanks. Helping with my WWL FOMO. :)