At first glance the concept of limiting bandwidth may seem counterintuitive. It seems reasonable to assume that more bandwidth is better. But, as it turns out, this isn’t always the case and a reason for why Tektronix introduced bandwidth limiting capability in its oscilloscopes are few years ago.
One example of where too much bandwidth can be a problem is with a noisy signal. Since the captured signal is inherently noisy or jagged, the oscilloscope may trigger on multiple rising edges leading to a fuzzy trace and ghosting.