Recommend a camber gauge?

[2bars]

Just redid the test and also measured the angle with a protractor, which showed the 2 and 3 degrees I was expecting. At 2 degrees the gauge showed a bit over 2.5 degrees but at 3 degrees it went off scale (+6). The scale on the gauge is linear and I don't think that a bubble in a fluid filled pipe will move linearly as you tilt it, this would explain what I'm observing, but still not sure as I don't know enough about the physics of bubbles in pipes...