A tube for an optical observation device, in particular for a microscope, with a viewing level that is linearly variable in length and/or height, wherein the tube has an optical light path, in which at least two optical elements are disposed, for example, deflecting elements. The tube can be designed, for example, as a swing-in tube, with a base part, wherein a deflecting element is disposed in the base part so that it can rotate around an axis of rotation, and with an eyepiece support that can swing in relative to the base part, wherein a deflecting element is disposed in the eyepiece support so that it can rotate around an axis of rotation. The optical elements may be disposed so that they can move independently of one another in the optical light path.