Buying and using an oscilloscope

[ppppenguin]

While the capacititive loading at the scope's input socket is often around 30pF by the time you've connected a cable then there's often 100pF or so. Enough to seriously affect many circuits. Hence the use of a 10:1 probe. This reduces the capacitance in the same ratio as the attenuation. So in a practical probe, with the scope's capacitance plus that of the cable you'll typically end up with 10pF or so at the probe tip.