Grant Asked:

I have a pair buying antibiotics online that says they are 8 x 21 and field 7 but i have no idea what that means?

Reply:

8 refers to the power of the binoculars. They bring objects 8 times closer. 21 refers to the diameter of the objective lens in mm. 7 refers to the field of view in degrees. It is common currently to express field of view in feet per 1000 yards. 7 degrees is about equal to 365 ft at 1000 yards more or less. That is about average.