A device for carrying an optical instrument, the device comprising a harness, an arm, and an extendable string, wherein, the arm comprises a first portion being fixed in relation to the harness, and a second portion for supporting of the string, and the string comprises a first portion and a second portion, the first portion of the string being arranged for fastening of an optical instrument, characterised in that the device further comprising an adjustable counter force device, and threads, the counter force device is arranged such that to allow the said device to be suitable and adjustable for a plurality of different weights of optical instruments, and the second portion of the string being attached to the adjustable counter force device for providing a counter force on the string, wherein the adjustable counter force device comprising a spring, a lever arm, and a support wherein the lever arm comprises a first point pivotably attached to the support, a second point attached to the string, and a third point attached to a second point of the spring, wherein a first point of the spring being pivotably attached to the support, and the second point and/or the third point of the lever arm is arranged to be movable along the lever arm by means of said threads, such that a counter force exerted by the counter force device on the string is adjustable. a harness, an arm, and an extendable string, wherein, the arm comprises a first portion being fixed in relation to the harness, and a second portion for supporting of the string, and the string comprises a first portion and a second portion, the first portion of the string being arranged for fastening of an optical instrument, the arm comprises a first portion being fixed in relation to the harness, and a second portion for supporting of the string, and the string comprises a first portion and a second portion, the first portion of the string being arranged for fastening of an optical instrument, characterised in that the device further comprising an adjustable counter force device, and threads, the counter force device is arranged such that to allow the said device to be suitable and adjustable for a plurality of different weights of optical instruments, and the second portion of the string being attached to the adjustable counter force device for providing a counter force on the string, wherein the adjustable counter force device comprising a spring, a lever arm, and a support wherein the lever arm comprises a first point pivotably attached to the support, a second point attached to the string, and a third point attached to a second point of the spring, wherein a first point of the spring being pivotably attached to the support, and the second point and/or the third point of the lever arm is arranged to be movable along the lever arm by means of said threads, such that a counter force exerted by the counter force device on the string is adjustable. the device further comprising an adjustable counter force device, and threads, the counter force device is arranged such that to allow the said device to be suitable and adjustable for a plurality of different weights of optical instruments, and the second portion of the string being attached to the adjustable counter force device for providing a counter force on the string, wherein the adjustable counter force device comprising a spring, a lever arm, and a support wherein the lever arm comprises a first point pivotably attached to the support, a second point attached to the string, and a third point attached to a second point of the spring, wherein a first point of the spring being pivotably attached to the support, and the second point and/or the third point of the lever arm is arranged to be movable along the lever arm by means of said threads, such that a counter force exerted by the counter force device on the string is adjustable. a spring, a lever arm, and a support wherein the lever arm comprises a first point pivotably attached to the support, a second point attached to the string, and a third point attached to a second point of the spring, wherein a first point of the spring being pivotably attached to the support, and the second point and/or the third point of the lever arm is arranged to be movable along the lever arm by means of said threads, such that a counter force exerted by the counter force device on the string is adjustable.