Nauticam 8.5 dome ports

Two question regarding the 8.5 dome ports by Nauticam.

• Other than white balance is there optical difference between the two?
  
• Is the white balance port worth the extra cost?
  

Thanks in advance.

You mention the 8.5". Are you trying to compare the glass domes from Nauticam, i.e. the 9" Glass Dome vs. the 9" Glass Dome with WB? or are you comparing the 8.5" Acrylic dome to the WB port which would leave for a very drastic price difference?

The domes on the standard dome port and the white balance dome port are identical for acrylic and I'd imagine the same is true for optical glass.

You mention the 8.5". Are you trying to compare the glass domes from Nauticam, i.e. the 9" Glass Dome vs. the 9" Glass Dome with WB? or are you comparing the 8.5" Acrylic dome to the WB port which would leave for a very drastic price difference?

I was actually compering the two 8.5 acrylic. One says WB and the other doesn't. I didn't know the 9" could fit my 10.5 (I used a port finder on backscatter.com). Is the glass that much superior for its price?

Those with glass ports are likely to defend their purchase, however for optical qualities and IQ there really isn't anything to support the view... in fact you could argue that a well made acrylic dome will provide better IQ due to the closeness of the material to water itself as opposed to glass. You do however gain scratch resistance from glass but then you are also unable to polish out minor scratches from glass. The reality is that you can gain greater IQ by ensuring that your settings and lighting are chosen to achieve the best exposure of your subject than worry too much about the dome material (assuming that you have the correct extension length fitted of required for your lens of course). So, you really need to weigh up what qualities are right for you re both dome size and material. I'm an acrylic dome user and an 8" one. I don't do close focus work with it so getting an extra couple of inches closer is not required and I gain a little less corner softness with the added dome size.

As for WB or not... I would save your money and go standard. If you shoot RAW don't worry about it at all.