Extended ISO range is a completely artificial, conjured up set of ISO values that are purely created by the camera’s software manipulations. When actually used to take an image, the camera uses the highest native ISO value available and then boosts the exposure using the camera’s image processor.
It is a pity that most people miss the incredible gift that is the custom settings on a camera C1, C2/ U1, U2. They are super powerful tools which can easily.
The Looney 11 rule really makes shooting the moon easy and straightforward. For a newbie photographer, this is an absolute godsend.