The German Panthers and Tigers had great stadia type reticles within their sights, which the tank commanders and gunners had to do range estimation based on target size and possible distance . The M1 Abrams' preferred sight is the thermal imaging system (TIS) which is viewed through the Gunners primary sight. The sight has an illuminated reticle which is projected into the sight by the laser range finder. The range finder along with the ballistic computer can accurately produce ranges to targets and effectively aline the main gun for the proper angle / elevation / deflection all based on current conditions. About 1 second in all. Now if the those sights go down, then there is the back up Gunners Auxillary sight (GAS), which is modeled after the 105D from the M60 series. It is similar to the sights used during WWII. To compare WWII tankers to modern day tankers, by their skill level, the older tankers had to really learn their craft in order to prevail on the battlefield. In modern day tanks it is basically -- see the target at long range, put reticle on target area, lase to target, and then fire at target. Very easy, almost like playing a video game.