3 hours ago, Adventurer said:

Yes, overall better! There is nearly no sharpness loss in the edges with that combination.
I am not shooting the Canon RF 24-105mm f/4-7.1 STM IS behind a dome.

But this is can be mainly credited to the lens behaviour on land, were you can see that center and corner sharpness is excellent in the f-stop range we typically use underwater. Also the barrel distortion at 24mm helps when using domes and underwater correction optics. Of course this lens has been roasted as dismal performer in land reviews for that. But for our kind, this is exactly what we need in underwater photography. ( source: review at OpticalLimits.com )

I repeat / clarify, that I am not shooting the Canon RF 24-105mm f/4-7.1 STM IS behind a dome.

I happen to own a unique Rebikov / Ivanoff Style corrector port which allows decent zoom through with that lens. With some tinkering, trial and error I lucked into this lens and specific uw glass combination, and I believe to currently be the only underwater photographer using such a system. There is a complete thread about my lucky find in this forum:

https://waterpixels.net/forums/topic/2637-ivanoff-style-underwater-corrector-port-on-a-canon-marelux-mx-r6ii/

Can you post some examples of what type of images you take with this system you have put together? What kind of FoV are you getting?

@Adventurer could you show us which kind of photos are you getting with your system?

I'm very curious about this Ivanoff system