The 1.5x auxiliary objective lens increases the magnification of a stereoscopic microscope while reducing the working distance to 47mm and the field of view by 1.5x compared to a conventional objective.
The magnification of stereoscopic microscopes is primarily increased due to the eyepieces. When observing through eyepieces, the auxiliary objective lens is used when the magnification achieved with eyepieces is not enough. When capturing with a digital camera, eyepieces are not included in the optical design and, therefore, an auxiliary objective lens is used.
The auxiliary lens is screwed onto the objective cap.