The student disassembles the lens.
text: Ok.
text: There is a black button under the EOS mark.
text: Where is it?
text: The EOS mark is on the camera, other side.
text: Other side.
text: On the right, right. EOS.
text: Okay.
text: And under there is a black button, press and hold it. Turn the camera lens.
text: Okay.