The oscilloscope DC Gain Accuracy is ±(3%*range) for Normal or Average acquisition mode, with 5V/div to 10mV/div.
In your picture, the Accuracy is ±0.48V.
You can change the voltage scale to 1V/div to measure.
Or click "Acquire->Average mode" to open average acquire mode to reduce the noise.
Post time 2016-11-7 09:19:53