3rd AXISI know windage and elevation. What is the purpose of a 3rd plane adjustment on a target sight? Is it to bring the pins into better focus per the archer's preferences (or eyesight) or does that 3rd plane adjustment mean something completely different?
IT's just the DOOR SWING angle.
Imagine that your sight ring is a DOOR.
Now, imagine the door hinges,
so that you can SWING the door
and change the angle of the door swing.
Let's say you bump your sight ring against a tree
and then the DOOR swings towards your face 45 degrees.
This is an EXTREME example.
If the arrow is level,
the sight bubble will still be in between the two lines.
climb into your tree stand,
and aim the arrow downhill.
Be very careful to NOT tilt the top of the bow.
The bow is still aimed downhill,
but the bow is NOT tilted left,
the bow is NOT tilted right.
look at your sight bubble.
Guarantee you the bubble will NOT be in between the two lines.
That's what the door swing angle adjustment is for.