Note the effect of the AC coupling filter on the signal. (Blue is sinusoidal sweep from 100 mHz to 500 Hz without AC Coupling, with a varying offset of 0 V, 1 V, 2 V, or 3 V; Red is same signal AC Coupled. No analog filters affect the sweep bandwidth.)
Note the magnitude response of the filter @500Hz sampling frequency.
A zoomed in section of the magnitude response at the lower cutoff corner.