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Discussion Starter · #1 ·
Im thinking of getting a scope, never had one before. In my research this word "parallax " keeps coming up. I asked a few gun shops and they all gave me double talk and b.s. anybody want to answer? thanks in advance for any replies
 

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I'll go out on a limb on this one. Parallax is the difference in where an object, target, appears in the scope when looking through it and where it really is. It is caused by the image from the objective not being coincident with the crosshairs. One of the best tests I know of is to set the rifle on sand bags. Align the scope with the target. Without touching the rifle, move your eye around in back of the scope. If the crosshairs move on the target, the parallax in the scope is not set for the range of the target.

If you've ever looked into a pond and seen something close to shoreline and grabbed at it and missed....that's parallax. The object was not where your eye thought it was.

Adjustable objectives fix this problem. Fixed objectives are set at the factory. I think most set rifle scopes at 150 yards, shotgun is 70 yards.

Anyone else have any input on this one?


:sniper:
 

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That's as good an explanation as it gets. I'd like to take a stab at it from the driver's seat. A new driver experiences parallax because they're sitting in the left seat instead of the center of the car. They can't quite tell when the car is centered in the lane until they learn to shift their "aim" in reference to the centerline, off their left shoulder. It's about optical illusions.

As far as scopes go, it's about the shift in centerline as you move your head around trying to acquire target. With respect to vertical alignment, you get less parallax error if the scope is mounted low to the barrel. All scopes are balanced to reduce parallax with magnification, so it's usually tougher to get your head just right when on higher magnification.

So you have to "personalize" your rifle for higher magnification. You will find a best shoulder-to-eyepiece adjustment with a little experimentation and patience. It takes a few trials to get it good. It's right when you put your rifle to shoulder and you naturally have a sight picture at higher magnification. One inch makes a hell of a difference.

Hope this helps.
 
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On a side note, people are dominant in one eye, just like they are in one hand. Most people are dominant on the same side, but some aren't.

Some folks insist this affects your aiming point if you're "cross dominant", but I'm right eyed and right handed, so I can't tell you for sure.

You can tell which eye is dominant by looking at something tall and slender with both eyes. Close one eye, and see if the object seems to jump to one side. Repeat with the other eye. For me, the object "jumps" when I only use my left eye, but looks the same with both eyes or just the right.
 

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Is parallax what makes different people shoot the same weapon differently? My buddy and I can shoot the same rifle with the same scope, and our points of impact will be about two inches from each other. This happens with several rifles, not just one. We are always amazed at that.
 

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PARALLAX=The apparent displacement of an object, especially a star or other heavenly body when it is view successively from two points not in the same line of sight, It is a diurnal or geocentricl parallax when the observers change of position is caused by the earths rotation on its axis annual or heliocentric parallax when the change of position is caused by the earths revolving around the sun .

Sumation:: to deviate or change:2guns:
 

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Bigdog- I think that may be attributed to the difference in your eyes and your friend's; and the difference in shouldering the weapon. Not really sure.

095- What dictionary gets credit?:rolleyes:


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So, now that we know what PARALLAX is, the next question is how do we deal with it when we shoot. (Assuming no objective lense adjustment is available)
What we need to do is make sure our eye is aligned with the scope CONSISTANTLY. How we achieve this is by making sure all those circles we see when we look through the scope are CONCENTRIC. (Mainly that black ring around the field of view, should be a nice round ring, not a crescent)
A consistant eye alignment straight through the scope will help minimize the parrallax effect.

BIGDOG - you move to the head of the class!:beer:
Two different shooters holding thier eye in a different place will make the rifle shoot differently. The same with one shooter inconsistantly aligning his eye from shot to shot.

I learned this lesson the hard way and wasted alot of ammo chasing my shots and experience loads of frustration.
 

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Discussion Starter · #9 ·
WOW. thanks for all the responses. I think i got an idea of what it is all about.
So would a scope with out an adj. objective be less accurate at farther distances?
Would it be more likely to have bigger groups?
Thanks for the help.
 

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Depends on how far we're talking about. Most scopes are set at around 150 to 200 yd. That's why most Obj Adj scopes are 4x14 or higher.
So, if you're shooting prairie dogs at 400, you'd like to have it.
Otherwise, just keep that sight alignment concentric and you'll be fine.
:usa:
 

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A few Ideas on holding your head in the same place. These have mostly been used with Iron sights but they’ll work. We teach privates to shoot an M16 with their nose on the charging handle. Those of us with glasses find that this makes it hard to bring sights and target into focus and have to move our head back to increase the sighting radius. When I carried a CAR-15 I found that the edge of the collapsible stock fit nicely into the corner of my mouth. For several years after when I had returned to the M-16 I used to put a piece of tape on the stock at the corner of my mouth like those little tabs bowhunters use. Shooting is all about consistency if you can do exactly the same thing every time the group size shrinks and hitting the target becomes a matter of sight adjustments.

Jeff
:usa:
 

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Originally posted by DocWagon
On a side note, people are dominant in one eye, just like they are in one hand. Most people are dominant on the same side, but some aren't.

Some folks insist this affects your aiming point if you're "cross dominant", but I'm right eyed and right handed, so I can't tell you for sure.

You can tell which eye is dominant by looking at something tall and slender with both eyes. Close one eye, and see if the object seems to jump to one side. Repeat with the other eye. For me, the object "jumps" when I only use my left eye, but looks the same with both eyes or just the right.
Dear doc,
Tried out your method of checkin' dominant eye.
Tall,slender gal cross the street. Looked with both eyes...
closed one eye...she jumped to one side!
closed the other eye....she cussed at me.
closed both eyes....she threw a rock!!!
guess i learned 'bout dominance,though.

Happy 4th.
 
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