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Range finding using parallax.
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Optics Jedi Knight
Lord Of The Flies
Location: South Africa
During the thread of "heat and POI shift" a blogger posted about the effects of heat on air rifle shooters ability to range accurately. He made the statement that for evry degree in air temp change the distance ranged can alter by 1 m. And the total shift on 55m can be 20m.
I found this intriguing and posted a few queries. So far this blogger has not responded. This prompted me to blog on an air rifle site and ask the same questions..
I learnt the following:
If you get 12 responses, you get 12 different answers.
The air rifle guys calibrate their parallax focus dial for distance.
Given the right circumstances the right scope can accurately focus (range) up to about 75 meters.
They shoot up to 55 meters and by focusing precisely (or dialing out any parallax) they can accurately tell the distance up to 55m by reading off the focus dial numbers.
For this you need a scope with a minimum of 30X magnification. Mostly 50X is used and works best.
No-one could verify or confirm that air temp effected the accuracy of such focusing/ranging.
Most agreed that light or shade on the target effected accuracy of focus and can be by as much as 8m on 55m.
The type of target effected the accuracy of ranging. The less reflective the target the better, so they tend to rather focus on a different surface then the target, such as a fence pole, tree bark etc.
This form of ranging is not an exact science, but when done correctly can be effective or better then nothing.
So for now this other blogger on our site was speaking a bit of bull.
But I found this info ineresting and thought to share it.
Edited by 8shots - September/27/2010 at 05:35
Optics Master Extraordinaire
Location: Benton, Pa
Thanks Wouter,good info!
Pearls of Wisdom are Heard not Spoken
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