The 2X teleconverter can be installed on our Modular Optical Imaging System (OiS200) equipped with the optogenetic add-on and dual camera imaging. It allows changing the focal length of the bottom lens by 2x, offering a field of view 2 times larger. This is especially useful at high frame rate and limited ROI. 2 teleconverters can be attached for a field of view 4 times larger. The teleconverters will prevent using the optogenetic stimulation when installed.