Putting aside subjective considerations of habit and preference, there are some strong objective reasons to reconsider fixed-power scopes. Chief among them is optical brightness. Because they contain fewer lenses, fixed-power scopes tend to be brighter. You’d notice the light-transmission benefit if you put a fixed 4X next to a 3X–9X (the latter set at 4X) at twilight, but I have actually measured the difference. At 4X, the fixed-power scope is about 8 percent brighter than the variable. At 6X, the benefit is about 12 percent in favor of the fixed-power model. As you move up in magnification, the brightness benefit increasingly favors fixed-power models.