I'd like to share about how to customize white balance Canon DSLR for capturing reeftank photo. Hope this thread usefull for Canon DSLR user.
We need White Balance Cap like this.

Set the Camera Dial to Av (Apperture Priority).

Switch the lens to Autofocus and if you're using tripod then switch image stabilizer to Off.

Setting the camera as display below.

Compose FTS and press shutter button.

The FTS will look like this.

Switch the lens to manual focus.

Put the WB Cap in front of the lens and press shutter button.

We will have the picture like this.

We need White Balance Cap like this.

Set the Camera Dial to Av (Apperture Priority).

Switch the lens to Autofocus and if you're using tripod then switch image stabilizer to Off.

Setting the camera as display below.

Compose FTS and press shutter button.

The FTS will look like this.

Switch the lens to manual focus.

Put the WB Cap in front of the lens and press shutter button.

We will have the picture like this.
