I recently acquired a Nauticam housing for my Sony A7RII, and am a bit lost trying to figure out what extensions will/won’t work to house a lens I already have and would like to use. I could use some advice if anyone can help.

The housing is the N100 system, and the lens I am trying to work with is the Sony FE 14mm f/1.8 GM. According to the Nauticam port chart, they recommend the N100 to N120 35mm adapter (which I have), followed by a N120 20mm extension (which I don't have), then the N120 180mm glass dome (which I have).

The question I have: Forum member Onokai is selling a 100mm compact 20mm extension. (https://waterpixels.net/forums/topic/3635-brand-new-nauticam-compact-port-extension-ring-20-18520/#comment-25602) Would that extension work just as well as the N120 extension if I switched up the order to be 20mm extention → N100/120 adapter → 180mm glass dome? (Neither he or I are sure.) Or, is there a reason I don’t understand that the 20mm extension needs to come after the adapter, such that the compact extension won’t work?

Edited 5 hours ago5 hr by wdeutsch
Fixing readability

41 minutes ago, wdeutsch said:

I recently acquired a Nauticam housing for my Sony A7RII, and am a bit lost trying to figure out what extensions will/won’t work to house a lens I already have and would like to use. I could use some advice if anyone can help.

The housing is the N100 system, and the lens I am trying to work with is the Sony FE 14mm f/1.8 GM. According to the Nauticam port chart, they recommend the N100 to N120 35mm adapter (which I have), followed by a N120 20mm extension (which I don't have), then the N120 180mm glass dome (which I have).

The question I have: Forum member Onokai is selling a 100mm compact 20mm extension. (https://waterpixels.net/forums/topic/3635-brand-new-nauticam-compact-port-extension-ring-20-18520/#comment-25602) Would that extension work just as well as the N120 extension if I switched up the order to be 20mm extention → N100/120 adapter → 180mm glass dome? (Neither he or I are sure.) Or, is there a reason I don’t understand that the 20mm extension needs to come after the adapter, such that the compact extension won’t work?

The only reason I think that might give you trouble is if the lens is too wide through the N100 part of the extension. Obviously the bottom part will but this is a fairly fat lens that only gets narrower right at the bottom, but I expect it's probably OK. You can test to see if the lens fits through the N100-N120 you already have.

The question you haven't asked is if you really want to use this lens UW? Wide rectilinears have their uses of course, but the 180mm dome geometry requires the lens to be positioned with the entrance pupil forward of the optimum point at the dome centre of curvature to avoid vignetting, meaning the lens won't perform as well as it would properly positioned. You will see that the port chart shows the 250mm dome with an " * " meaning that is the optimum dome to use. The 180mm dome will certainly work and the images produced will be usable but other lenses may well do better particularly in the corners,

There are other Sony lenses which may work better with the 180mm dome. I would suggest asking for experience using the Sony 180mm dome with the 14mm f1.8G lens, to see if you would want to do that. Apparently some of the new 16-35 lenses work quite well with the 180mm and I think there have been some tests published on this site from memory.

The other question is what sort of photos are you thinking you might like to take and is a 14mm rectilinear the best option for this?

Im going to say yes, but with reservations.

1. If the lens uses zoom/focus gear and its supposed to be manipulated with the knob in the adapter, its misaligned.

2. Does the lens fit through the N100 part completely

3. And i think compact port extension system is actually N85, not N100. Here is the 30mm version with the same SKU#

-edit

Also the old compact port system looks its threaded attachment? Im sure someone has better info than my guessing, but it is over 10 years old system.

Edited 5 hours ago5 hr by Sokrates

17 minutes ago, Chris Ross said:

The only reason I think that might give you trouble is if the lens is too wide through the N100 part of the extension. Obviously the bottom part will but this is a fairly fat lens that only gets narrower right at the bottom, but I expect it's probably OK. You can test to see if the lens fits through the N100-N120 you already have.

The question you haven't asked is if you really want to use this lens UW?

The lens will fit entirelty through the N100 end of the N100/N120 adapter, so I think I'm OK on that front. Your point is well taken on whether this is really the lens I want to use. To be transparent, this is a practical solution, not a perfect one. I have the 14mm lens, and an extension to make that work is only a little money. A new 16-35 lens is a chunk of change that I'd rather not spend just right now while I'm getting started. Down the road, I'll probably go that route.

Thanks for the input and advice. It's very appreciated. :)

16 minutes ago, Sokrates said:

Im going to say yes, but with reservations.

1. If the lens uses zoom/focus gear and its supposed to be manipulated with the knob in the adapter, its misaligned.

2. Does the lens fit through the N100 part completely

3. And i think compact port extension system is actually N85, not N100. Here is the 30mm version with the same SKU#

Good points to consider. Thanks for raising them.

1) No zoom function to worry about. I'm OK (I think) using autofocus only. I can probably 3d print a modified focus gear down the road if I want that function. Worthy of consideration, though!

2) We're good there. The lens passes through the N100 end of the adapter with room to spare.

3) I would love clarification on this from anyone who knows for sure. This is part of what I'm trying to figure out.

Looks like it is N120 afterall, but it also looks to be threaded so its a no-go with current N120 system. https://www.bluewaterphotostore.com/nauticam-n120-compact-port-extension-20 Says it needs the compact base adapter and compact system port, with threads.

Also the picture on the for sale ad looks like it has threads (to me).

https://fotografit.eu/upload_dir/pics/Nauticam/Lens-charts/2015_01_Nauticam-Port-Chart.pdf also the old port chart has only the 18XXX extensions with only the 18XXX ports/base.

But again, im not 100% on this, its just Claude working for me.

Edited 4 hours ago4 hr by Sokrates

1 hour ago, Sokrates said:

Looks like it is N120 afterall, but it also looks to be threaded so its a no-go with current N120 system. https://www.bluewaterphotostore.com/nauticam-n120-compact-port-extension-20 Says it needs the compact base adapter and compact system port, with threads.

Also the picture on the for sale ad looks like it has threads (to me).

https://fotografit.eu/upload_dir/pics/Nauticam/Lens-charts/2015_01_Nauticam-Port-Chart.pdf also the old port chart has only the 18XXX extensions with only the 18XXX ports/base.

But again, im not 100% on this, its just Claude working for me.

Thanks for that legwork! That's good enough for me to hold off on this one.