Abstract: An adjustable stand having a first spindle, a second spindle and a flange for connection to and positioning of an optical observation instrument. Positioning of the instrument relative to the stand is maintained by a torque compensation device respectively arranged with at least one of the spindles to compensate against torque caused by the mass and positioning of the instrument and spindles. Each torque compensation device includes a brake for securing the spindle, a spring, a motor for adjusting the spring tension, and a motor controller which includes a transmission device with a transmission ratio deviating from 1:1 and which is positioned between the spring and the spindle. The motor controller controls the spring tension by selectively rotating the motor based on instructions from a control unit, which receives signals from a spindle-position sensor and a spring-tension sensor and automatically provides counter-torque rotational movement instructions to the motor controller.

Abstract: The invention relates to an adjustable stand for an optical observation instrument, in particular for a surgical microscope, with a tilt spindle 1 and with a swivel spindle 2 for the optical observation instrument and with a flange 4 for connection to the optical observation instrument or a further member of the adjustable stand, wherein, on at least one of the two spindles 1, 2, a first torque compensation device is arranged, which has a first brake 13 for securing the spindle 1, 2, and which has a first spring 11 which is connected to a first motor 12 for adjusting the spring tension of the first spring 11, and the first motor 12 is connected to a first motor controller, and which has a first torque transmission device 14 which is formed between the first spring 11 and the spindle 1, 2, and which has a first position sensor 16 for determining the position of the spindle 1, 2, and which has first force sensor 15 for determining the spring tension of the first spring 11, wherein the position sensor 16 and the