Having taken my G9 underwater about a dozen times, I upgraded to a G12. My G9 shots were fine, but I was not having success often (1 in 12 acceptable) which was quite frustrating for an accomplished and formerly professional terra firma photographer. I have found a robust G12 technique (1 in 3 acceptable) which has given me a lot of good raw content and resolved my three primary issues: too much blue in an image, blurred scenes, and illuminated floaties in the water.
Experimentation gave the following procedure for success:
1) Place the diffuser on the WP-DC34
2) Select the scene (SCN) mode on the top crown dial
3) Select the Underwater preset
4) Dial in an exposure compensation of -2 on the left crown
5) Force the flash on
Now, place the camera so that it is too close to the subject and take a picture. It will be overexposed with many blown highlights. Now, back the camera off just a little - less than a foot, and expose again. You may be surprised at the reduction of exposure from the small distance increase. Repeat until you get a good exposure. You'll also find lots of reds appear doing this.
In short, give too much light to the scene and reduce exposure by physically distancing the camera from the subject. Water gobbles up light very differently and much more quickly than the atmosphere. I have found it easiest to control exposure with distance.
(Not the best shot from this technique - still a little blue, but it's the image I have on hand.)
Dive safe. It's better to have a good dive tomorrow than a bad dive today.
