Over the last year I've followed several discussions about lens and dome / flat port considerations.  I've tried to follow the details but the discussions are usually between members who know far more about this than me.  They can assume "basics" that I just don't know.

I'm hoping I can motivate a knowledgeable member to write an article about this.  I know about, and have read into, various sites that have been referenced (such as Oceanity), but am hoping for something that would walk through a given lens, its placement with extension, and an ideal port determination.  Topics, for example, could be:

1. How to determine / estimate the lens entrance. pupil
2. How the entrance pupil and minimum focus distance translate into an extension
3. How example domes (maybe focusing on Nauticam) add XX dimension from their flange to the actual dome (interior?) surface.  Information on dome curvatures and their intersections with the flange.
4. How fisheye domes fit into all of this.

Hopefully this makes sense, and apologies in advance if I'm already showing just how much I need to learn this.

I know, from some past discussions, that manufacturers actually measure performance on a wet/dry fixture, but the calculation would be helpful as a starting point.

Gary

Super idea, Gary:

Alex M?

Chris Ross?

You guys up for that??

I made this presentation back in 2017 and then re-recorded it in 2020. There has been much progress in water contact optics since then - but it was aimed at being a decent introduction with a historical perspective

and

 

I do all the domes calculations by myself normally because I get a lens because it is officially supported that I know it will work

I think the primary issues that you have are

1. Determine the entrance pupil - if you don't have the lens design and want to calculate it reliably you need to determine the non parallax point this can be laborious

2. Most domes on sale with exception of some fisheye domes are not full hemisphere they are cuts and in many cases curvature radius is not published

If you know 1 and 2 it becomes straightforward. The key is to avoid entirely lenses that don't focus close and focus your effort on the right ones which are not necessarily the best lenses for your camera at that field of view.

I have thought about doing this write up many times on my blog for my own perusal (I forget certain things I do and serves me as notebook) but having recently changed format I need to keep this very very fresh so did not need o write it down

2 minutes ago, Interceptor121 said:

I do all the domes calculations by myself normally because I get a lens because it is officially supported that I know it will work

I think the primary issues that you have are

1. Determine the entrance pupil - if you don't have the lens design and want to calculate it reliably you need to determine the non parallax point this can be laborious

2. Most domes on sale with exception of some fisheye domes are not full hemisphere they are cuts and in many cases curvature radius is not published

If you know 1 and 2 it becomes straightforward. The key is to avoid entirely lenses that don't focus close and focus your effort on the right ones which are not necessarily the best lenses for your camera at that field of view.

I have thought about doing this write up many times on my blog for my own perusal (I forget certain things I do and serves me as notebook) but having recently changed format I need to keep this very very fresh so did not need o write it down

Do you want to write such article for Waterpixels?

2 minutes ago, Davide DB said:

Do you want to write such article for Waterpixels?

Yes can do I already offered in the members presentation to do some stuff for you guys as I used to do for Adam

Normally I do the write up for myself and you can get the content authored with some link backs etc etc

I am not planning to give a tutorial on how to determine the non parallax point if you don't have the lens design, that is a topic of its own

I would really appreciate a port / lens article, and I'm sure others would as well.  I've enjoyed reading the threads where this has been discussed, but have wished for more.  Thanks in advance for anything the community creates.

Gary

Go for it, Massimo!