Who used the backstaff?

The backstaff, an early navigation instrument, was primarily used by sailors and navigators during the Age of Discovery in the 16th and 17th centuries. It allowed them to measure the altitude of the sun to determine latitude while avoiding direct sunlight, which could damage the eyes. The backstaff was an improvement over the astrolabe and was particularly popular among English mariners. It was eventually replaced by more advanced instruments like the sextant.