you may have encountered in low-light situations is image blur. Generally, blur is caused by inconsistency in where light falls onto the sensor - this might be caused by the sensor itself moving and changing its position in space, or by the subject itself moving, and thus changing where the light falls onto the sensor.
The amount of blur you get as a % of the entire image is a function of three things: average rotational speed (how fast you shake), exposure time (shutter speed), and angle of view (a function of focal length and the crop multiplier of your sensor).
if we shake the camera faster, we get more blur. We tend to get more blur with longer shutter speeds. And if you use a larger angle of view (when you "zoom out"), you tend to have less blur. An important point to note is that each of these factors are multiplicative, rather than additive - zeroing one will zero the total amount of blur.
So if you had a zero rotational speed, it doesn't matter how long your shutter speed is, or how narrow your angle is - the blur will be zero. Similarly, with an extremely fast shutter speed (say 1/10,000s - close enough to zero), we also zero the blur, no matter how fast we shake the camera.
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