@Sandy Yu Hello Sandy, and great question! So C1 & C2 are custom modes, which means we can customize them with any of the modes and settings. Which ever Mode you have saved on your C1/C2 is the same control as the mode you have in the original mode (you can see in the lower left corner of your camera screen) which mode you have saved at the moment while in the C1 or C2. When saved and set, you can experiment and change the values of all the settings, change the mode and back, and its back to the original pre saved settings. For example, you can Save C1 with any of the different modes we have, but lets say we go with Aperture Priority mode - And set all the right settings for shooting with a Dive torch (see week 3 of the course). And then Save your C2 as Aperture Priority mode - but with the right settings for shooting with a Strobe (they differ a bit), and if you dive with the 2 different setups frequently you can pre set them, and every time you decide to just bring your Dive torch, set your Mode to C2 for a quick setup, or vice verse. You can go even more specific with this if you want to have a quick turn if you are shooting with a strobe for example, where you can set your settings for shooting Close up Macro on C1 and fish portraits on C2 and so on! 嗨 Sandy，很棒的問題！ C1 和 C2 是「自訂模式」，意思是你可以把任何拍攝模式和設定都預先存進去。當你切換到 C1/C2 時，相機其實就是在使用你「當初保存時」的那組設定（你可以在螢幕左下角看到它是基於哪個模式，如 A 模式、M 模式等）。 設定好之後，你在水下要調整參數、切換模式、玩設定都沒問題，只要切回 C1 或 C2，它就會自動回到你保存好的原始設定，非常方便。 舉例： 你可以把 C1 設成使用「手電筒」拍照的設定組合（我們課程第 3 週有詳細教）。然後把 C2 設成「閃燈」拍照時的設定組合（這兩者會有些細微差異）。 這樣每次下水前，只要確認你這次要用手電筒還是閃燈，一秒切換模式，完全不用重新調設定。 你也可以做得更進階，比如： - C1：拍超近距微距（Close-Up Macro） - C2：拍魚類肖像或生物全身照 當你需要快速切換拍攝風格時，轉一下模式盤就行了