This small refractor scope is normally used as a widefield finderscope to make the process of locating objects easier in the main telescope. The idea is that you align the finder scope with the main scope to give you an easy way to point the telescope at the object of interest.

With my finder scope, I have removed the eyepiece from it and replaced it with a small camera that allows me to use it as a guide scope. What this means is that once I have pointed my main telescope at a target that I want to photograph, the camera on the guide scope takes short (around 1 - 3 seconds) exposures and checks the position of a star in its field of view relative to a defined starting position. If the star has drifted, the guiding control software (PHD2 for me) sends a command to the mount to make a small adjustment in position to return the guide star back to the specific pixels on the guide camera sensor where it started.

The camera exposures on the main imaging camera are normally in the range of 30 - 600 seconds (occasionally even longer), so when guiding is active the control software is making frequent adjustments to the telescope position to ensure the minimum possible drift in position of the object being photographed. This is necessary because the gearing mechanisms in the telescope mount are never perfect, and if these imperfections were left uncorrected the final image would show signs of blurriness due to the movement of the object of interest across the camera sensor during the exposure.