What does the top dial on a telescopic sight control?

The top dial on a telescopic sight typically controls the vertical reticle, also known as the elevation adjustment. This dial is used by the shooter to adjust the point of impact of the bullet in the vertical direction. When a shooter spins the top dial, it raises or lowers the reticle, allowing for shooting at different distances or compensating for bullet drop due to gravity. Understanding the function of this dial is essential for accuracy, as it directly impacts how high or low a shot will hit on the target.

The other options pertain to different functions of the sight. The horizontal reticle adjustment, often controlled by a side dial, would adjust for windage, while illumination controls the brightness of the reticle, making it easier to see in varying light conditions. Windage adjustment itself is also managed by a different dial, allowing for adjustments to the left or right. Thus, recognizing that the top dial is primarily for vertical adjustments emphasizes the importance of familiarity with the components of a telescopic sight for effective shooting.