Sigma 15 mm + Small Dome?

Anyone have tried a Sigma 15mm f/2.8 EX DG Diagonal with a small dome?

I'm a little confused because Nauticam chart recommends a 140 mm (5'') port and that would be ok, but Ikelite only a 8'' port. I'm trying to make a real light setup for travel and freediving.

I don't think Ikelite have a smaller dome, so 8inch (compact or regular) is probably the only option there. 

In term of optical quality, I'm sure some will jump in to expise you the differences between different domes and what they implies, but the bottom line is smaller domes equal better handling but compromise on corner sharpness versus larger dome which are, well, larger... This mean travelling and handling constrain but better sharpness.

Smaller domes as a very general rule are normally good with fisheye lenses. Maybe not quite as good as the larger ones, but  in the real world it's not too easy to tell  the IQ difference. 

If you're using Ikelite then Zen do a mini dome for them, and there used to be the 5 inch precision dome by underwater camera stuff.  

Mike

Keep in mind that on the built in lens hood on the Sigma 15 may prevent you from using the smallest domes. For example, my sigma cannot be used with my 4 inch zen dome because the hood interferes. 

I know some people cut the hood of the Sigma 15mm (you can't remove it). But you have to be willing to use a powertool (like a dremmel) near the lense glass (I'm not). 

If Nauticam recommend the 5 inch dome, it should fit the hood. In term of size, this dome should be a good option too. 

12 minutes ago, OMorissette said:

I know some people cut the hood of the Sigma 15mm (you can't remove it). But you have to be willing to use a powertool (like a dremmel) near the lense glass (I'm not). 

Yeah - I actually made a post about that here too - thats what brought me to the forum today haha.