A method for determining a cylinder of an ophthalmic lens to be mounted on a spectacle frame is provided, the method including: providing a measuring device configured to run a Jackson Cross Cylinder procedure; determining components of a first vector of the cylinder in a two-dimensional vector cylinder representation; and determining components of a second vector of the cylinder in the two-dimensional vector cylinder representation, the components of the second vector of the cylinder being determined such that a Euclidian distance between the first vector and the second vector is independent of a value of the cylinder.