Answer: Context Effect
Step-by-step explanation:
Context effect refers to the influence that external factors (the environment, for example) have on the perception of a stimulus. This is a well-known aspect of cognitive psychology.
In fact, the situation stated in this question is a good example: It is not the same to observe the Moon with a naked eye and taking into account factors such as cloudiness, dust and whatever is surrounding this view that have effects on the observation; than observing this same Moon with a narrow tube in which our eyes focus only on the lunar surface, without taking into account the rest that surrounds that horizon.