A telescope of true vision provided the mundane ability of magnifying a viewed object by a factor of 50. Thus a ship at sea from 5,000 feet away would appear to be 100 feet away when viewed through the spyglass.
The enchantment upon these spyglasses pierced illusions and other magical misdirection, allowing the viewer to see an object in its true form.
A telescope of true vision had 20 charges. Upon using the last charge the lens would crack and the item would be ruined.