Dome ports specifications why is it so hard??

[Guest]

I had purchased the Nauticam 85" acrylic dome that on the instruction manual is labelled fisheye dome just to find out this is not at all a fisheye dome

 

The port is not a complete hemisphere it has a radius of 105mm but it is only 7cm deep which means the maximum field of view is around 140 degrees

 

In addition due to the flush construction it does not work properly with my 14mm rectlilinear lens either.

 

It would really be helpful if the manufacturers published the CAD data that they use for their products instead of producing port charts. I am not interested in 'will it work with lens x' I want to know how it is built so that I know that it will work best with lens x which is a totally different planet

 

I would really like to know how close to a hemisphere the 230mm glass fisheye port is because if the port chart says better results are obtained with the smaller 140mm port this means that also the 230mm port is not a fisheye port

 

[Davide DB]

Are you going to open your own brand of dome?

Interceptor121 segnature series 

 

[Guest]

47 minutes ago, Davide DB said:

Are you going to open your own brand of dome?

Interceptor121 segnature series 

 

It would be an idea. It is really disappointing to find such surprises.

Now I am having a hard time to explain the dealer why is not meeting my expectations as it works 'for all other customers in the world'

Of course it works it is transparent if you push a lens into it you will get an image, the point is what kind of image

[Davide DB]

Did you mean 8.5" (21 cm)?

A dome is forever 💠
Port and domes from Massimo San Felice's legendary Igloo/Underwave of the 1990s are still sold and traded.

 

[Guest]

2 minutes ago, Davide DB said:

Did you mean 8.5" (21 cm)?

A dome is forever 💠
Surely you know that port and domes from Massimo San Felice's legendary Igloo/Underwave of the 1990s are still sold and traded.

 

8.5” is around 21.6 but it turns out is a cut of a larger 24cm or thereabout

i have gone through almost any nauticam dome port for N120 only the 230 glass is left. That one looks more round but hard to say

[Chris Ross]

You could also look at Sea and Sea and Isotta ports, you can change them to Nauticam with just a change of lug ring, but of course domensions are hard to come by.  But if you want a cheap acrylic dome from Ali express they come fully dimensioned.  😂

Ali express dome

[dentrock]

The Nauticam N120 140 is not a complete hemisphere either. Its radius is 70mm but its height is 63 mm

[Guest]

2 hours ago, dentrock said:

The Nauticam N120 140 is not a complete hemisphere either. Its radius is 70mm but its height is 63 mm

Breaking news the nauticam 140mm dome doesn’t have a 70mm radius 

the radius is 69. Am not sure how you determined your 63 height the glass base is under the line of the metal.

If what you said is true the radius of the dome would be 137.5mm instead of nominal 138mm which is a bit different than the situation I reported because the entrance pupil of the lens will be anyway under the front of the lens and the lens needs to go in the dome which means the position will be correct within the range of the next 5mm precision

To bring it back to this example this port needed to be 9.5” wide so another 2.54cm larger

the issue with making larger radius dome shorter is that the centre of the dome goes behind the port and as you put in an extension the lens vignettes on the opening of the port not on the dome petals

[dentrock]

My measurements are accurate within + or - 2mm. I need the radius to check if a lens with a particular MFD will work with the port, and where the optical centre lies. I don't trust published port diameters.

 

69 vs 70 makes no difference for this purpose.

 

63mm (+ or - 2) is top of glass to port flange, a distance necessary to work out required extensions for a particular lens.

 

Would be great if manufacturers made this info available for those of us who want to go 'off piste' from published port charts.

[Adventurer]

On 4/19/2024 at 5:35 PM, Interceptor121 said:

I had purchased the Nauticam 85" acrylic dome that on the instruction manual is labelled fisheye dome just to find out this is not at all a fisheye dome

 

The port is not a complete hemisphere it has a radius of 105mm but it is only 7cm deep which means the maximum field of view is around 140 degrees

Dear Massimo, I second you on that and must confirm that 95% of the port chart configurations for domes suggested by the manufacturers are wrong and have at least 1-5 mistakes in them.

 

It was always rumored that Nauticam is the only reliable source correctly quoting their radius and specs but now with your post also that icon seems to crumble away.

 

It is no wonder that domes have a bad reputation and allowed the rise and hype of over-heavy and over expensive water contact optics in the past two decades.

 

PS: keep up the good work and publications in your blog. It‘s worthwhile reading and was the source that pointed me to optical bench hub and solved my of my positioning problems. Thank you!

Edited April 24 by Adventurer

[Guest]

1 hour ago, Adventurer said:

Dear Massimo, I second you on that and must confirm that 95% of the port chart configurations for domes suggested by the manufacturers are wrong and have at least 1-5 mistakes in them.

 

It was always rumored that Nauticam is the only reliable source correctly quoting their radius and specs but now with your post also that icon seems to crumble away.

 

It is no wonder that domes have a bad reputation and allowed the rise and hype of over-heavy and over expensive water contact optics in the past two decades.

 

PS: keep up the good work and publications in your blog. It‘s worthwhile reading and was the source that pointed me to optical bench hub and solved my of my positioning problems. Thank you!

Nauticam port charts are not always wrong however the dome design is not always the same so the outcome can change in some cases 5mm in some others 20mm 

the issue is that a port that is designed in a certain way will not produce great results no matter what

 

in this example if the 230mm glass port is closer to a dome it will produce better results of this acrylic port

not because is glass but because of geometry as the radius of curvature is the same not because is glass or else

it seems like the worst design are all used for acrylic ports while the glass ports are better 

not good news for consumers as glass ports cost 3-4x acrylic