In order to properly center my edge finding camera on my cnc I created this simple 3 part camera holder. It has 7mm shank (can fit into ER11, ER16, ER20..) and will allow you to offset camera into any position in XY plane so you can properly center your camera in your toolholder.
mount your camera
push into toolholder
look trough camera on your computer, manually turn the spindle and offset your camera in XY plane so that center of the screen is always pointing in the same point on your workbed.
lock the holder in place with dab of glue or with touch of hot soldering iron