Minidome on Nauticam for Sony A7r4

Hi all.

I have a Sony A7r4 with Canon 8-15 fisheye in a Nauticam housing. I use it with the 8`acrylic domeport. I would really like to use a mini dome for cfwa, but I can't see on the port chart if it is even possible.

Does anyone here use the same setup with a mini dome? and what combo?

The last entry on the Sony N100 port chart https://drive.google.com/file/d/1YRwHfXvXLqWK3NsfXjtGbm7gSEmAw4g0/view

has an entry for the metabones adapter and then refers you to the Canon N120 port chart. What this means is you use the N100-N120 35.5mm adapter and then use the recommended ports and extension for the Canon 8-15 in the Canon port chart which is the Canon 140mm dome and 30mm extension.     The adapter has a zoom knob, so presumably the Canon zoom gear mates with this zoom knob - you should check that with your supplier or someone using the combo may be able to confirm this for you.

I already use the adapter for the 8`dome, and also the zoom gear, which fits with the knob on the adapter.  I was hoping to use a mini dome smaller than the 140mm, but maybe that is not possible.

So your two best choices for the Canon 8-15mm Fisheye are the Nauticam 140mm optical glass port and the Zen 100mm optical glass port. Both Zen and Nauticam make the ports with and without the removable dome shade. You will need to remove the shade if you want to use the 8mm end of the lens, I am sure you are aware but what to point this out for others reading the thread. I have used both ports a good bit, the Z100 with the A7R II and III and the Nauticam 140 with A7R III and IV. The 140 port requires a 30mm extension which you may own, with Zen the extension is built in. I have used the 8-15 fisheye with both the Metabones and Sigma MC-11 adapters and see no noticeable differences. Both of these ports work very well but I lean a bit more towards the 140mm for a bit more sharpness near the edges of the frame at like f/numbers. I have also used this lens with ports from Aquapazza, Inon and Ikelite ports. I shoot this lens only at 8/9mm or at 15mm anything else crops off the top and bottom of the frame which is not to my liking. Images at 8mm and 15mm. 

I am sure all Sony A7 users would rather be using a Sony FE 8-15 or 15/16mm Fisheye but it does not appear that is in the cards any time soon for any of the full frame mirrorless cameras. A significant upside to mirrorless is that just about any lens can be mounted to the cameras with an adapter. Only some will have excerptible auto focus, case in point Nikon has an excellent 8-15mm fisheye I have used several times on Nikon Z6 & & with FTZ adapter. Unfortunately no quality adapter existed for Nikon to Sony hence the greater exodus of Canon DSLR users to Sony over Nikon DSLR users. 

To follow on from what Phil said, the port chart says effectively add any canon lens with metabones adapter using the extensions and domes recommended for using those lenses in a Nauticam Canon housing. 

Effectively once you add the 100-120 adapter and Metabones adapter treat the combination like a Canon housing and use the Canon port charts and of course this extends to the Zen port charts.   So you can add anything Canon based on this chart : http://www.jaredparsons.com/portchart/zen-only/by-combination-group/nauticam-n120/

That's not to say it will work well just that it will fit and perform optically like it would on a Canon system.   It depends on how well the lens in question plays with the Metabones adapter.  Bear in mind some of the options might require fitting the port over the lens as the lens/zoom ring may not fit through the N100 housing if they are too large in diameter.

This also applies by the way to the Micro43 system which has a similar entry on the port charts- so you can add a Canon 8-15 to a micro43 system which is particularly interesting as the whole zoom range is available.

I've been using the Canon 8-15 with Metabones adapter on my A7RIV for a few months with Zen 4" mini dome.  I can see no difference in the results from when I used the same lens/dome combination on a Canon 5DMkIII previously.  Just use what extension/dome port combination recommended by Nauticam or others* on front of the 100-120 adapter and it should all work nicely.

* I'm actually using a Zen Subal Type 3 mount mini dome with Subal 20mm extension ring as recommended by Zen with a Nauticam/Subal converter.  I also use a Subal 8" Type 3 dome with Subal 20mm extension ring as recommended by Subal with the Natuicam/Subal converter.