Wide angle Dome for Isotta housing?

Dear photographers, please I am thinking about getting an Isotta housing, I was wondering if I can put any dome port on it or if I have to use only the ones from the brand of the housing... (incredibly expensive )what If i would like to put an Ikelit dome port? do i need to check some specific measures to fit or something else??

Isotaa's only wide angle port bigger than 8inch is this one...

https://www.isotecnic.it/en/wide-angle-dome-port-b120/ports-for-b102/dome-port-9-crystal-b120-detail

I was wondering if i can put this one... or maybe some other brand???

https://www.ikelite.com/products/dl-8-inch-dome-port

thanks!

The domes are expensive for a reason the Isotta dome is glass while the ikelite acrylic.  Acrylic domes are buoyant and scratch easily but you can polish out the scratches.  Glass is harder to scratch but really not possible to polish out damage and handle better as they are not trying to float up.

There are adapters available to adapt to other systems but they normally add extension which might be a problem and they might need to be custom made.  Backscatter has some available:  https://www.backscatter.com/department/SLR/type/Port-Adaptors 

They are mostly for adapting Subal to Nauticam or similar expensive systems though there is one for adapting an 8" modular Ikelite dome to Nauticam.   If you went with Nauticam you could buy the 8" Ikelite dome plus the adapter for $400 plus $240 for the adapter = $640 or get the Nauticam 8.5" acrylic dome for $724.  (backscatter prices) To me saving less than $100 is not worth it - for the hassles in sorting out correct extension and there may be other compromises.  There's nothing listed for Isotta adapters.

This shows the importance of looking at your housing selection from a complete system standpoint.  In Aluminium housings you can often buy for example a m43 housing , the camera and one of the lenses you want for the cost of just the full frame camera housing - depending on the specific model you look at.  m43 housings are smaller and importantly the dome ports are smaller and lenses are cheaper.  Yes you have a smaller sensor - but it's fine for many purposes.  If you are shocked by the price of the domes then maybe it is worthwhile thinking about a different approach.

By the way a 9" dome is huge and can be a problem for traveling - which lens were you proposing to house in that dome?

Chris, thanks for the feedback... I want to add these 2 lenses:

Sigma 15mm F2.8 EX DG Diagonal Fisheye

and one of these 2:

Canon 16-35 f4

Canon 16-35 f2.8 (Mark 2 or Mark 3)

Please what size the dome should be used for these? I been suggested an 8 inches should do the work, can you confirm? If yes, based on the size of the dome which housing and set up would you suggest please? I contacted Isotta because I quite like their products, they told me a housing is coming soon for EOS R, but they confirmed they have no 8 inch housing and nothing is compatible from other beands, so with isotta the only choice above 8 inche is their glass 9 inches  which costs too much and would cross my budget limit... so, if I would like an 8 inch dome under 1000 usd, what set up do you suggest? Should I stick with Ikelite? Or a Nauticam setup is better? or something else??  I am going crazy on what to choose....

The fisheye can be housed in a smaller dome - on Nauticam their 140mm glass dome is recommended, but it can be used in bigger domes or the 4.33" acrylic dome.

The 16-35 lens is the most demanding and to get good corners you need the 230mm dome.  The Nauticam port charts list options to use the 8.5" acrylic dome and smaller domes but don't expect good corners at 16mm.  The S&S correction lens is also recommended to help with corners. 

The reality is that housing a full frame camera is an expensive option and made doubly so if you want to house a wide rectilinear lens.  Having said that it does depend a little on what you plan to shoot - big animals with bluewater in the corners should be acceptable.  It's hard finding images that show this online here is one link which gives you some idea what to expect: https://uwaterphoto.com/?p=839

That link also talks about the S&S correction lens and shows the difference it makes.  At top is a photo on full frame with a 170mm dome showing corner softness.  The link also has a couple of frames from a 200mm dome with a 17mm lens showing that with the S&S lens an 8" dome is probably OK - depending on your standards.

On the lens choice I would suggest the f4 lens - you will never need the extra stop underwater so save your $$ and put it towards a big dome!

On Ikelite vs Nauticam or others - plenty of people are happy with ikelite housings - they are built to a price but they are cheaper for a reason.