Mirage - why is it important?

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Leo
Posts: 67
Joined: Mon Oct 05, 2009 9:10 pm

Mirage - why is it important?

Post by Leo »

Hi - I was searching on some of the historic posts on mirage and I was hoping to gain a better undertanding of "why" it's important and "what" it does. This summer will be my first shooting outdoors 50/100m and I although I'm familiar with heat mirage while driving (above a roadway) - I've never looked through a scope and seen it at 100m... and I'm curious given recent threads on high-end scopes.

Is it like windage - but in a vertical sense (hold over)?

If it ever warms up in MI perhaps I'll get to see first hand. :)
Rover
Posts: 7004
Joined: Sat Nov 15, 2008 4:20 pm
Location: Idaho panhandle

Post by Rover »

Back in the day I used to shoot "Bench Rest" in competition. This is where reading mirage really pays off.

You should focus your scope (you can't effectively read mirage by eye) a little in front of the target. You use the mirage to read the wind.

If the mirage is leaning to the left, you have wind from the right (and vice-versa). The amount of lean lets you judge wind speed. You want the same amount of lean for each shot. If the mirage stops leaning, you know not to shoot until it returns to its previous condition. OR, you can try to wait for conditions when there is NO wind or when you think the wind has "commited" and get your shots off very quickly (machine gunning).

Mirage can also move the "image" of the target. With my rifle on a rest (so I KNOW it was not moving) I have watched the bullseye move completely off the cross hairs.

It can all get very fussy, but now you have the basics and can start LOOKING.
Leo
Posts: 67
Joined: Mon Oct 05, 2009 9:10 pm

Post by Leo »

Rover... well that complicates things a little!!! :)

1) interesting that the miragre (temperature plane or humidity differential?) would be able to be "tilted" by a horizontal force... I might have thougt ripples or "waves" in the unconformity would have been the expected result
2) how do you adjust optical point of aim to bullet impact is it like light defraction? What happens if the mirage plane is in your bull set - adjusting different targets differently?

It has my interest... thanks for your note! Leo...
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Freepistol
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Joined: Sun Feb 10, 2008 5:52 pm
Location: Berwick, PA

Post by Freepistol »

Leo, You don't need warm temperatures to have mirage. All that is needed is for the sun to heat the ground between you and the target.
If you want to see what mirage does, have another shooter fire at 100m and watch the mirage and the effect it has on the bullet impact.
It's a lot of fun to shoot in the wind!
Rover
Posts: 7004
Joined: Sat Nov 15, 2008 4:20 pm
Location: Idaho panhandle

Post by Rover »

Leo, take a spotting scope and sit down near an asphalt street and just look.

Not only will you see the mirage "lean" but you'll also see it "running" (moving across your field of view). It will also "boil" (go straight up and down).

The mirage is somewhat anchored at the bottom and starts to move or lean as you go up.

The thing to do is just LOOK. You'll quickly see what is happening. The trick then is to correlate your shot with what you are seeing. This is called experience. You only get that by trying, although a good reader coaching you will certainly help.
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