Thread: Desirable features of an all round NZ hunting rifle

Originally Posted by 6x47

... Parallax causes aiming errors which become important obviously at longer ranges where there is far less leeway for error, esp in wind. You need everything going your way. I'm also a F-Open shooter so am acutely aware of these things.

BTW, the amount of parallax error at any given magnification does not vary with the objective diameter. If your 18X scope has a 40 or 56mm objective, there is no difference in that variable.

Thanks 6x47. I guess parallax isn't central to the "all rounder" topic but I'm curious, if you've looked into it a lot.
Is there a formula for the amount of aiming error due to parallax ?
I'd sort of intuitively thought it would be something like:
Aim error in mRad is proportional to (Target distance / Parallax set zero distance) x (distance of sighting axis from optical axis of scope)
I'm not sure where magnification would fit in, if at all.

So, I had assumed that if the exit pupil is larger, there is more potential for your eye to be further away from the optical axis of the scope.
Certainly good technique, centering your eye on the scope, is a traditional basic for long range shooting.