Canon EOS Rebel T6s EF-S 18-135mm IS STM Lens Kit Instruction Manual - Page 66

Q Displaying the Electronic Level You can display the electronic level on the LCD monitor and in the viewfinder to help you correct the camera tilt. Note that you can check only the horizontal tilt and not the forward/backward tilt. Displaying the Electronic Level on the LCD Monitor 1 Press the button.  Each time you press the button, the screen display will change.  Display the electronic level.  If the electronic level does not appear, set [53: z button display options] so that the electronic level can be displayed. Horizontal level 2 Check the camera's tilt.  The horizontal tilt is displayed in 1° increments. The tilt scale is marked in 5° increments.  When the red line turns green, it indicates that the tilt is almost corrected.  Even when the tilt is corrected, there may be a margin of error of approx. ±1°.  If the camera is very tilted, the electronic level's margin of error will be larger. During Live View shooting and before movie shooting (except with u+ Tracking), you can also display the electronic level as described above. 66