Canon EOS REBEL T6 (W) Basic Instruction Manual page 137

If necessary, also read "NFC Function Cautions" (p.W-15).
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When touching the smartphone to the camera, be careful not to drop the

camera or smartphone.
Do not touch the smartphone to the camera with too much force. Doing

so can scratch the camera or smartphone.
Just holding the smartphone close to the mark may not establish a

connection. Be sure to touch the mark with the smartphone so that they
come into contact with each other.
Recognition may be difficult depending on the smartphone. Touch slowly
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while changing the position or rotating horizontally.
Another application on the smartphone may start depending on how you

touch. Check the position of the p mark, then touch again.
When touching the smartphone to the camera, do not leave anything
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between the camera and smartphone. In addition, when a case is
attached to the camera or smartphone, communication may not be
possible via NFC function.
The camera cannot be connected to two or more smartphones at the

same time.
By default, the connection settings via the NFC function are saved as the

fourth setting (a setting dedicated to NFC connection) under the name
[SET4 (NFC)]. When you connect the camera to another smartphone via
NFC, [SET4 (NFC)] will be overwritten.
While connected, the camera's auto power off does not function.
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Connecting Automatically with the NFC Function
W-21