Originally Posted by Adam
Top of the trajectory is the top of the trajectory. Perception doesn't enter the equation, only physics.
You can choose to align your sighting system with this point or with another point. If you choose a point lower than apogee, the sighted rig will be "zeroed" at two ranges.
When set to touch the trajectory at a single point, a higher sight line relative to the bore will touch the trajectory curve further away than a lower one.
... is what you meant.
Erm not quite.
The top of the trajectory, the apogee is the muzzle. Everything further out is below this. It starts falling as soon as it leaves the barrel (assuming the barrel is horizontal)
If you change the scope height, you do move the tangent point, where the line of sight coincides with the trajectory, further out. It touches once. You can then chose to move zero down, so it touches twice, before and after the tangent point.
In reality, for FT shooters with a normal scope height, the tangent point is between 25-30 yards, and that won't change unless the speed is increased or the scope height is changed. That's where people set 0 to, and then dial up for ranges closer or further away. Of course you could put 0 at 35 yards, and dial up for ranges further away, dial down for closer ones, then dial back up for closer ones even still... but that, most would say, would be daft.
The point of percieved top of trajectory is defined by the pellet's trajectory and
scope height. Which is what Brian worked out a long time ago in a post far far away.