How to be certain?

[Alcadhrim]

So I own a D60 in a RDX D60 (S and S).

I would like to use a fisheye and the only one which work on my camera is the Sigma 10mm.
I order it and the Dome port ( CX Dome port) in a well known shop (in France).

THe problem is that they did not send me the rigth Dome, they say that is pointless because this other dome is far better than the which I ordered.

Ok.

But...

I need to use this dome with a port base, I ordered that in Taiwan in a shop I have used a lot of time. The guys send me a mail that the dome in question won't work properly with my lense.

Indeed the S and S chart says that only the CX dome port will work correctly. ( I guess they know their products better than anybody)

Do you know something which can help me to determinate if I can use this dome with my lense. (Mathematic or something I mean)

[scottg]

The sea & sea dome port chart is often incorrect.

The sigma 10-20mm will work better with a larger dome port. The CX dome port is a smaller dome port (6 inches).

Which dome port did they send you? Let's start with that, then we can talk about which port extension is best

[Alcadhrim]

The Optical dome port.

The chart often incorrect (an important point to keep in mind )

[scottg]

hmmm, which dome port did they charge you for? the optical one is much more expensive.

I believe the optical and CX are both 6 inch dome ports. They should use the same extension ring with the sigma 10-20mm. Try the 40mm ring, you need either the 40mm or the 40mm+ 20mm, but I'm guessing just the 40mm will be fine. But I'd rather shoot that lens through a larger port. Also do a pool test with and without a +2 diopter.

btw, I did some pool tests between the optical port and NX compact dome port and found no difference.
http://www.uwphotographyguide.com/sea-s ... -port-test

[Alcadhrim]

Ok, the item I would like to order is now only the port base (which change my RDX in NX mount) to use the optical dome.
The point is that if the Optical Dome is not ok with my lense, I send it in return and order the compact dome.

Do I need a extension ring? It seems not (on the S and S chart ).

[scottg]

the CX dome port optical dome port will perform similarly, but the optical post is much more expensive. you need a 40mm extension ring