If you choose "Select Device" from the main menu in Bandicam:
... and then in the "Device Selection" dialog, you click the "Settings" button:
... and then in the Properties dialog, you select the "Camera Control" tab:
There is a "Zoom" setting in that dialog, with a default value of 0, and a slider that allows you to change the value to anything up to 9. But when I change the value for the Zoom setting it doesn't appear to make any difference to the recordings I make. So what is this setting supposed to do?