The distance between the center of the exit pupils. Usually adjustable.
A measurement of the distance between the center point of the pupils of the eyes of the interpreter. This distance will vary slightly by individual and is often important in properly setting up the stereoscope used for interpretation.
Distance between the two eyepieces. Typically it is adjustable to accommodate different users. Some microscopes also have graduated scales to indicate the actual distance between the eyepieces, allowing a user to determine the optimum number and then quickly set it before each use. BACK
The distance between the centers of a person's pupils. Every binocular has a range of movement, by pulling the barrels inwards/outwards, to accommodate different IDs - e.g. "56-72mm" means the minimum ID is 56mm and the maximum ID is 72mm. If your ID is 54mm you will never be able to see properly through such a binocular because the barrels will never line up with the centers of both your eyes. Tips: Most binoculars have an adequate interpupillary distance range for most people. However, if children will be using the binoculars often you may want a binocular with a minimum ID of around 56mm or below.
Commonly referred to as PD, the distance between your pupils. Go to Top
The distance between the centres of the pupils of the eyes when vision is at infinity. IPDs can range from 55 to 75 millimetres in adults, but the average is usually taken to be around 65 mm, the distance used for most resolving calculations and viewer designs.