佳能S90，G11水下拍照TIPS（摘自www.uwphotographyguide.com）

Here my recommended Canon S90 and Canon G10 / G11 underwater settings, if you are using an external strobe or flash:
有外闪时

Canon S90 / Canon G11 settings for Macro
微距

* Manual mode, F5.6, 1/500th, ISO 100 手动模式，······················

* Zoom in half-way 镜头ZOOM一半（这样就不需要靠太近，不至于因为闪光太近过曝，个人经验，用YS-27DX，如果不打开中灰滤京，即使是最低一档，也会过曝，离开一点就好很多）

* Macro mode, auto white balance, flash on forced flash mode（相机设成微距模式，自动白平衡，强制闪光---引闪用的）

* Turn internal flash to it's lowest power setting（内闪调到最弱的输出-----当然，否则还会制造一些雪花的，BACK SCATTER）

* Strobe on manual power; adjust strobe power as needed（手动调节外闪输出）

Canon S90 / Canon G11 settings for wide-angle & fish
广角或拍鱼

* Manual mode, F5.6, 1/125th, ISO 100

* Zoom out（用最广角端）

* ** Adjust shutter speed as needed to control background exposure （可手动调节快门来控制背景曝光程度）

* Auto white balance, flash on forced flash mode

* Strobe on manual power; adjust strobe power as needed

* Turn internal flash to it's lowest power setting

* If you are using a fisheye lens or dome port, turn macro mode on（如果用了鱼眼镜头或....厄运港口#$%&@#知道什么东西，一直不知道怎么翻译,调到微距模式）

If you don't have an external strobe / flash:
如果没有外闪（为什么不买一个呢，好很多的，因为，WITCH IS NO FUN！）
You are shooting with the internal flash. In manual mode, the camera won't set the exposure of the flash automatically, you'll have to set the flash power yourself, which is no fun. To get that capability, which is basically TTL with the internal flash, use Av Mode, F5.6. In bright conditions, use Av Mode, F8.
使用光圈优先模式，F5.6，在光比较充足的情况下，用F8

网站上还有不少有用的知识，有兴趣的朋友可以自己去找来看。