Esatto Wedge

The Esatto 2 has two 5mm threaded holes on the fixed outer casing. I don't know if it's what they're intended for but I use them to fix the unit to a Vixen bar. It's handy because if using a thin tube lightweight scope tube rings aren't needed. Not only does this avoid extra parts but it means the entire weight of the focuser and camera train aren't cantilevered on the tube/Esatto adapter interface.

Somewhat frustratingly the surface the holes allow attachment to isn't parallel to the optical axis. Theoretically the massive cone error this introduces makes no operational difference after alignment but consensus suggests otherwise. A wedge fixes it nicely.