Under which condition should binoculars NOT be used?

Using binoculars can be compromised under various environmental conditions, but it is especially important to consider visibility factors when deciding whether or not to use them. Binoculars are designed to enhance visibility and allow for a better view of distant objects, but they work best under clear conditions.

In foggy conditions, the moisture suspended in the air scatters light and reduces visibility. This scattering means that even with the magnification provided by binoculars, the clarity and detail of the view will be significantly impaired. The fog acts as a barrier between the observer and the object of interest, rendering the use of binoculars ineffective. In such circumstances, relying on binoculars may not provide any significant advantage, as the very reason for using them—enhanced visibility—will be lessened due to the fog's presence.

Overall, while binoculars may not perform well in extreme wet conditions or darkness, their utility can still be somewhat effective under certain circumstances (like low light or brief showers), but fog truly diminishes their overall effectiveness, making it a less suitable condition for their use.