So, I'm pretty much decided on getting the OMD-E M10 and AOI housing to replace my aged Sony NEX-5 and Nauticam setup -I'm after something a bit more up-to-date in autofocus and image quality but want to downsize a bit for travel and can't justify the cost of a new Nauticam housing anyway. This seems to tick the right boxes for me.

I'm now weighing up lens and port options and the UWL-400A wet lens looks very appealing on cost compared to a dome port and lens. I have the fisheye adapter for the Sony pancake lens and 4" dome port but to be honest I've rarely used it so I don't think I'd miss having a fisheye option -I would have preferred a wide zoom setup for versatility. I'm assuming that a wide zoom lens (9-18 or 7-14) with a small dome port would be sharper and lighter than the wet lens, anyone got any real world experience?

I cannot tell about the AOI system, but had EM5-II and EM1-II in Nauticam housings (my wife is still using EM1-II in Nauticam). I was using both Zuiko 9-18mm and Pana 7-14mm together with Zen DP170. IQ (sharpness and microcontrast in the middle) was not very impressive, all images looked a little bit "soft" ...

My wife now uses Zuiko 8-25mm behind Zen DP170 (a lot of extension is needed!) and IQ is very good - the best MFT/WA combination I personally have ever had in my hands...

The question is whether AOI housing can use this or a similar domeport... ?

Wolfgang

P.S.: I, personally, would not like to "downgrade" from Nauticam housing to AOI (and there might be a lot of extensions/ports you could continue to use with your new camera (?) - this should be considered and added to the cost calculations). IQ and AF wise the EM10-III is pretty similar to EM1-II (I guess) and there might be a good second hand purchase available...

This is not exactly a wide zoom (12-45) but you can see some shots at 12mm in the AOI 4" semi-dome port at

https://www.mu-43.com/threads/olympus-12-45mm-f-4-pro.107818/post-1795979

My impression is that this is a lot sharper than my old 12-50 in a flat port, but of course I could be biased. If you don't need to go very wide, this port is not too expensive (around USD300 when I bought it). I think the 9-18 is the only other wide-ish zoom AOI says is compatible.

I had the impression the UWL-400A is designed for the smaller sensor TG5/6/7. Before you buy one, make sure it will work with a mu4/3 sensor.

Edited 10 hours ago10 hr by d2b
add missing "UWL-400A" before "

It seems that adapting the Tokina 10-17 mm Fisheye zoom from Canon aps-C to m43 is an interesting option. Depending on the adapter (0.7x vs. 1x) you get a full fisheye or a slightly „teleconverted“ version on the M43. I am not sure whether this fits well into the AOI housing, you may need to work on the adapter mechanically because it has a tripod mount. If you search on this site, I think @Chris Ross has a nice description for this setup.

Other than that, the AOI housings likely pair really well with the Panasonic fisheye for a very compact system. I use a cheap-version of this with the manual focus fisheye from Samyang/Rokinon etc. This is a good „entry drug“ for fisheye but I‘d recommend spending a bit of extra money for a used Panny Fisheye. Mostly because then you can also control the F-stop during the dive. Dome etc. is the same, but you need to zoom with the fins. And convince the fish to stay in place, which I find difficult at times.

If you wanting improved AF, and spending to get it, I would think the AF in EM1-MkII/OM-1 would be better than the EM-10. I don't know how patient you are but you could probably pick up an EM-1 II or III Nauticam housing for around the price of the AOI housing secondhand. I'd certainly do that before getting an AOI housing as you get a proper viewfinder rather than the back screen. Buying new I think perhaps an OM-5/EM-5 III might be a better compromise as it has the AF from the OM-1. You could also look into Isotta and Aquatica housings as they are quite a bit cheaper than Nauticam these days.

As others have said the 9-18 and Pany 7-14 are not the sharpest knives in the drawer. I have the 7-14 and rarely use it and the 12-40 and the fisheye get more use. Look into what port system you have and how well it accommodates these lenses, some of the bigger ones have to be fitted from the front. I now use the Canon 8-15 with a metabones on my system, not exactly cheap but amazing flexible as it covers a fisheye and a 7-14 lens in one package with excellent image quality all the way. Wet lenses on the other hand use kit lenses. By all reports the m43 14-42 lenses are quite good at the wide end with the WWL for example but the quality drops off at the long end.

You mention the UWL-400 wet lens, the ad blurb for this is talking about using it on TG-6/7, the price of these tends to scale with sensor size as the task for the optics gets more demanding with bigger sensors. The difference in size from a TG7 to m43 sensor is significant so I expect the corners may be a bit wanting with m43.

The Sony fisheye adapter has a pretty poor reputation for optics even on land - you say you are not much of a fisheye guy - why is that? Generally fisheyes are the lens of choice for reef scenics and CFWA and if you can use a fisheye zoom all the better. The Tokina 10-17 with metabones speed booster is also reported to be an excellent very flexible option to use on m43 and works well in a 4"dome so very compact. The choice of lens has a fair bit to do with what sort of subjects you are looking at CFWA for example needs to focus very close and rectilinear zooms are not up for that in general.