If your smartphone has multiple camera lenses, follow the steps shown below to find the right camera lens to perform a proper measurement:
STEP 1: First try out the lens that is nearest to the flash. (If your smartphone has multiple lenses that are spaced at the same distance from the flash, try them one by one)
STEP 2: Start your measurement by tapping 'Start measurement' and hold your finger on the lens for 15 seconds.
STEP 3: Check to see if the measurement effectively starts. You will know when the seconds start counting down and the screen shows your heart rate.
STEP 4: If your device does not start the measurement, move on to the next camera lens.
Tip: Do not cover up the flash with your finger. The flash can get hot during the measurement.
