After the countless and extremely technical discussions about the compatibility of the most exotic lens-port combinations, I would also have a question and my own strange combination.
I am too illiterate to try to make any calculations and assumptions on my own so I am asking you techies. (As I ask the question imagine my face like that of the famous math meme...)

 

 

 

I would like to ask you in general what considerations should be made in putting an anamorphic lens behind a dome but let's take a specific lens: Laowa Nanomorph 20mm T2.2.

 

https://laowacine.com/product/nanomorph-20mm-t2-2-mft/

 

I found this table:

 

 

It has a MOD of 430 mm (not promising for focusing the virtual image generated by the dome).
What is the minimum porthole size of this lens?
How do I calculate the position this lens should have inside the dome?
The data indicate an FOV of only 65° compared to how wide the view seems in the footage.

 

 

Thank you for your help.

 

David,

I have a naomorph 27 mm setup on a fuji aps. I use the Nautical 180 mm with a 55mm n100 to N120 adapter withe the focus knob. I need to  use a +2 diopter to get it to focus 10-14 inch from the film plane(tested dry).  I have not tested in real conditions. Will have a trip at end of month, will get a chance to get some wet tests. Will post as soon as I can footage.

Fantastic lens topside.

9 minutes ago, Tobyone said:

David,

I have a naomorph 27 mm setup on a fuji aps. I use the Nautical 180 mm with a 55mm n100 to N120 adapter withe the focus knob. I need to  use a +2 diopter to get it to focus 10-14 inch from the film plane(tested dry).  I have not tested in real conditions. Will have a trip at end of month, will get a chance to get some wet tests. Will post as soon as I can footage.

Fantastic lens topside.

 

The 20mm has the same MOD: 43cm / 1’4″

I have ready available a 230mm dome and i have to focus an object at about 5m / 16'

Where is the virtual image focus distance (underwater) on that dome? Try a +2 diopter.

 

Check these resources .:https://www.hydroflex.com/flat-and-dome-lens-ports

 

On a 8 inch dome(true hemispherical) the virtual image should be around 10-15 inches in front of dome. The lens needs to be able to focus down to 10 inch to focus on the virtual image.

Placement of the lens as to the dome front is somewhat critical. The Nodal of lens, point should be at the radius point in the dome. 

                                        

Edited May 15, 20241 yr by Tobyone
expand info

hey @Davide DBand @Tobyone i have been tinkering the same lately with anamorphic. have you tried shooting anamorphic uw ? very curious of the result...

 

Thank you 

No, I didn't try. Dome and virtual image math is against anamorphic 😞

 

 

every problem has a solution 😜