Compudude, let me rephrase my original post. I know exactly which lenses physically will fit and work with which housings, I just wanted an opinion from someone who has actually had them in their hands to play with. I spend a fair bit of time lurking, and have actually read all of the surrounding threads, but no one said straight out that the fisheye fix uwl-04 (natively 52mm...that comes with an adapter which must be used for 67mm housings) such as my ikelite would work with little vignetting or without having to zoom my little cheap camera so much that it's even worth it. And I know that Nemrod has creatively made an adapter for his ike a570 housing to use with ad mount lenses such as the inon 165fe, and that I found a similar solution...the ikelite part #9306.79, which I assume allows attachment but not practical use of ad lenses on 67mm threaded housings. All this being said, I am left to decide the "safe" route...w20 (obviously will work! it'd better on the same manufacturer's housing), inon uwl-100 maybe adding the dome later (expensive), or trying to make the sweeter fisheye lenses inon 165 and fisheye fix uwl-04 work with the aforementioned adapters;risking the inherent problems with digicams in housings with bulky ports that have bulky attachments for wet lenses.
Why compudude, are you saying I should read the threads to find the answer, when in the same sentence you say no one has it? (we don't really know with certainty what will, and what won't work, I suppose I did come to the wrong place, I regret my first post already! Too bad reef photo and backscatter are far far away from me. And too bad everyone posting only speculates how anything will work.
Sorry if I came off harsher than intended.
The fact is, however, no one has the answers you seek, because no one has the same combination of hardware that you do, except Ryan. Everything in every one of the threads is speculation and guesswork... you asked questions that had been discussed in nearly every one of the threads, all of which were still relatively active, and all of which had been determined to be "we don't know yet".
The people at Fix
might know. Ryan
might know, IF he has received the updated adapters from Fix. Those are the only ones with access to all the possible permutations of housings and lenses.
In all the discussion and all the threads, there's only a handful of people with housings in their hands... and fewer still with housings AND wide angle lenses AND a way to connect the two. And I have yet to see
anyone who actually has the Fisheye UWL04 lens in their hands, other than Ryan and the folks in Japan.
Everyone really wants the answers to all the questions. Everyone has been contributing every sliver of information they have to try to get the big picture, but frankly it's all incomplete. I directed you to the current threads because you weren't really asking anything new, and the questions had been discussed before. These weren't old and buried threads, these were current threads still on the first page. All mostly unresolved.
I say this as explanation for my briefer response earlier. I hope you understand what I was getting at now.
With regard to the 9306.79 bayonet adapter, it is very similar to the 9306.80 adapter I use with my Ikelite housing for my S80. If you look at
Ikelite's chart, however, which lists housings and cameras and their compatible accessories, you'll note that the S90 housing only officially supports Option "B", which is the Ike W20 lens or other 67mm-threaded lenses. Only housings which support Option "E" are compatible with the 9306.79 for adding bayonet lenses. The PDF makes it clear that the connection method they use is the same as the connection method my adapter (9306.80) uses, three screws hold it in place via friction against the outside of the existing housing's lens tube... the screws go into a groove around the lens tube. Looking at how large the S90's lens tube is (designed for 67mm threads inside it), and the fact that there is no similar groove, it doesn't look to me like there is much likelihood the 9306.79 will work with the S90 housing. Just a guess, but it's an educated one nonetheless. Ikelite's documentation would have to be wrong, and past design decisions would have to have been radically changed for that to work.
) in the ikelite housing which has 67mm threads on the port. I'm looking to purchase a wet lens that will increse my FOV. The w20 is an option and I can get for a reasonable price, however it seems that lenses like the fisheye fix uw-04 and inon 165fe would be better. I understand for the inon 165 fisheye I would need an adapter to make that "ad-mount" lens work with my housing. I checked and I believe ikelite has recently released a part. 
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Ha ha......
