I just want to give a short feedback, although I believe I am the only one here in the forum with the Canon R5/Nauticam combination... I've now bought pretty much all the essential equipment I'll need in the near future. A super dome for split shots will certainly follow at some point, but it's not needed right now. At the beginning of June '26, I was able to gain some initial experience, but only so far with the following setup: Canon R5 in a Nauticam housing with Nauticam 140mm fisheye dome Canon EF 8-15/4 Fisheye with Canon RF 1.4 extender adapted with a Commlite EF/RF adapter and Saga zoom ring 2x HF-1 Backscatter strobes incl. 4500K flat diffusors, most of the time with homemade snoot I will soon be testing the Canon RF 100/2.8 macro lens (possibly in combination with the Nauticam SMC-1) with the OS-3 Backscatter snoot and/or homemade snoots. I might also test the Canon RF 2.0 extender on the Canon 8-15/4. Due to poor visibility and wide angle, it didn't make sense to test the TTL capabilities of the e-TURTLE 3 SMART TTL converter. This test will be carried out in July and I will report on it here. My experience was as follows: The Nauticam housing isn't really well-suited for Eye-AF (due to the lack of a lever – there is only a button – for the *-button). Virtually all Canon photographers assign Eye-AF and Spot-AF to the AF-On and *-button for quick switching between the two AF functions. I reluctantly assigned the function to the depth-of-field preview button (for which Nauticam provides a lever down on the right!) and can therefore operate it with my right little finger. However, pulling this lever and simultaneously releasing the shutter while wearing thick gloves isn't exactly easy. Eye-AF is mostly useless underwater, but it sometimes helps, especially with cuttlefish. The lens hood of the 140mm fisheye dome does not appear to be manufactured 100% symmetrically (or the camera is not optimally positioned in the housing), at least when zooming out I always see the lower right part of the lens hood first - minimal, but it is annoying and 'costs' some focal length. What experiences have other users of this dome in combination with zoom lenses? But perhaps I should ask this question in a separate thread. Following the instructions of @Dave_Hicks (many thanks for that!), I had an extension printed for the HF-1's power intensity knob, which was incredibly helpful. Nevertheless, I'd also like to have one for the mode dial, as switching between M and SC mode is very difficult with thick gloves. Why can't manufacturers put themselves in the shoes of cold-water underwater photographers??? As I've mentioned in another posting, the combination of the 8-15/4 lens and the Canon RF 1.4 extender is optically superior (especially in the corners) to the combination with the older Kenko 1.4 extender. The disadvantage with the Commlite adapter is that the EXIF data isn't displayed correctly, as the extender itself isn't apparently recognized. This isn't a major issue, but I had to be careful not to stop down too much out of habit, because I always had to add an extra stop of exposure - unfortunately, it has happened a few times anyway - I have to slowly get used to it. All in all, apart from the minor flaws I have described, the equipment functioned reliably. Underwater conditions in the Dutch North Sea were far from optimal due to very poor visibility (between 1-3m), and therefore I mostly shot with very low strobe power (mostly 1/16), usually with a snoot and higher ISO. Because of the annual cuttlefish mating, I always try to spend a few days diving there around this time of the year. Of course, in some of the images I had to extensively remove backscatter during post processing. 😉 Btw: with these images, it obviously makes no sense to show crops from the corners. I hope to be able to deliver that later this year. All images are uncropped. The following four pictures were taken on the first day, when visibility was still at its best, up to 3 meters. Therefore, all pictures were taken with two HF-1 strobes (left/right) and slightly more strobe power (if I remember correctly, up to a maximum of 1/4.). Moon Jellyfish F25 (forgot to open up the aperture 🤐) | 1/250sec. | ISO 400 | @17mm: Moon Jellyfish F22 | 1/250 sec. | ISO 400 | @ 20mm: Common Cuttlefish (very small, just about 20cm long) F18 | 1/25 sec. | ISO 640 | @ 21mm: Common Cuttlefish (very small, all of them just about 20cm long) F20 | 1/25 sec. | ISO 640 | @21mm: The next two pictures are from day 2. Visibility was significantly worse than on the first day (especially noticeable in the second picture) and therefore only possible with a snoot. Common Cuttlefish couple (snooted) F22 | 1/250sec. | ISO 400 | @21mm: Common Cuttlefish couple (snooted) F14 | 1/25 sec. | ISO 800 | @ 21mm: On day 3, visibility was initially quite good (1st picture), but was becoming significantly worse later. Common Shore Crab & Common Spider Crab F20 | 1/40 sec. | ISO 1000 | @21mm 2x HF-1 strobes (left/right): Common Cuttlefish lays eggs (snooted) F16 | 1/40 sec. | ISO 1000 | @21mm: Common Cuttlefish couple (snooted) F16 | 1/40 sec. | ISO 1000 | @21mm: Common Cuttlefish couple (snooted) F16 | 1/40 sec. | ISO 1000 | @21mm: