Has anyone tried using the $30 Peak 10x suction cup loupe that sticks to your gr oundglass? Buy three and stick on your ground glass to define your plane of foc us then tilt, swing, and focus away. This must be a joke, right? The DOF at 10 x must be so small, and the flexibility of the suction cup and lack of focus adj ustments? would make this device completely useless, right?