Canon G-20 Flash Blocker

[promocop]

What exactly is the deal with this white card one needs to put on the outside of the housing to block the ineternal flash of the Cannon from scattering light ? I was just about to pull the trigger when I was told you need this blocking card!! ***? Spend $1,500 on a camera and housing and you need this mickey mouse card on the OUTSIDE to block the internal flash?!!!

 

[promocop]

SORRY..meant G-10 and the housing is a 'fisheye'

 

[Kukuisa]

I think you mean the card to block the light from the internal flash when using an external flash. Came it with the camera or with the housing?
And do you use an external flash ?

K.

 

[Larry C]

Spend $1,500 on a camera and housing and you need this mickey mouse card on the OUTSIDE to block the internal flash?!!!

In a word, yes. If you're diving in SoCal, and you've got a lot of algae and little swimmy critters that you can hardly see, and you want to take pictures with an open water background you'll need to block the internal flash (which is too close to the port) to prevent the reflection of all that stuff from making little white bubble looking things (backscatter) all over your nice picture.
If you're shooting fish portraits and pictures of lobsters with a rocky background from 12-18" you're probably fine using the built in flash, but for anything wide you'll need to use an external flash or custom white balance with no flash. The external strobe can be positioned far enough from the lens and aimed to avoid reflection to some extent. The flash blocker (a strip of old film negative also works fine) is normally used in conjunction with a fiber-optic cord to fire the external strobe.

 

[promocop]

external flash And what do you recommend?