Viewport Rotation Constraint

[Neil Cooke]

Hi,   I've tried but I can't find it.   When I rotate using RMB + alt + shift, I can constrain the rotation to the x axis more or less but only in 45 dgree steps. Is their a command which will allow viewport camera rotation to be constrained to only one axis but not in steps?   Maybe a numerical input for the viewport camera? But if so where would that be?   Thanks   Neil Cooke