Instruct: Classify a given review into positive or negative sentiment.
Query: Disappointing performance

These binoculars are fine at 12X, but almost totally unusable above 20X. The field of view becomes increasingly smaller until at 60X you are looking through a fuzzy peephole. There was a defect in the left optics, either a piece of dirt or a nick in one of the optical units. Ather five minutes of use I packed them up and sent them back.