How important is paralax?

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  • How important is paralax?

    Hey guys,
    Say i was to use a scope with a 100m parallax then shot at 50m and 25m what negative effects would occur?
    Thanks guys.

  • #2
    negative effect is you miss. Parallax error can occur when your eye does not line up exactly with the center of the scope as you only have one reference point in space the reticule. So if you eye is out your shot will be off. an easy and effective way to eliminate parallax is with an accucover. However they don't work in the dark.

    www.accucover.com

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      Sorry for a dumb question guys but say with a nikon prostaff 4-12x40 scope with parralax set at 100m would it have a clear image at say 25, 50 and 100m?

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      Originally posted by CrabbyCrab" post=43601
      negative effect is you miss. Parallax error can occur when your eye does not line up exactly with the center of the scope as you only have one reference point in space the reticule. So if you eye is out your shot will be off. an easy and effective way to eliminate parallax is with an accucover. However they don't work in the dark.

      www.accucover.com
      Ill have to pick 1 of these up i reckon.

  • #3
    An easy way that I check is to get behind the rifle and line up the target then set my parallax so the image is clear, then move my eye/head left and right, up and down slightly. If the cross hair moves in relation to the target it's wrong. If it stays aligned with your target, it's probably good. This is very useful when shooting through mirage as it's difficult to know what the clearest sight picture is.

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    • BlueBikesBlackGuns
      BlueBikesBlackGuns commented
      Editing a comment
      Originally posted by dinofreak" post=43610
      An easy way that I check is to get behind the rifle and line up the target then set my parallax so the image is clear, then move my eye/head left and right, up and down slightly. If the cross hair moves in relation to the target it's wrong. If it stays aligned with your target, it's probably good. This is very useful when shooting through mirage as it's difficult to know what the clearest sight picture is.
      This is the best practical description. If parallax is out when your head moves the cross hair drifts across the target and thus your shots will be inaccurate. When parrallax is correct your head can be positioned in different locations behind the scope and the cross hair will still appear to be in the same location (the location where the round will fall).

      As for your question at 100m and less probably not enough error to make any real difference for hunting purposes. If you want to get serious and shoot long range competitions then this will be a show stopper.

  • #4
    Or re-parallax the scope to say 35M. That's what I did with my non-AO Nikon Prostaff for my MRod. There's plenty of clear, simple instructions online as to how its done

    Originally posted by allrounder_13" post=43600
    Hey guys,
    Say i was to use a scope with a 100m parallax then shot at 50m and 25m what negative effects would occur?
    Thanks guys.

    Comment


    • #5
      Parallax is defined as the apparent movement of one object in relation to another by a change in position of the observer.

      We say 'apparent movement' as if the observer is moving (or in different positions for each observation) and is unaware of his movement then he can believe that of two stationary objects, one or both of them is moving.

      For scopes, the eye is the observer, and the reticle (image) and the target (image) are the two objects.

      What this means in relation to riflescopes is that if the image of the target is not in the same plane as the reticle (crosshairs) within the scope then the condition known as parallax exists. Optically speaking Scopes can only be parallax-free at one range.
      Parallax correction is not focus but appears that way to the human eye when high magnifications are used.
      Adjustable objective scopes allow for the image of the target to be moved into the same plane as the reticle. This is why images appear blurred at high magnification when the AO is set to a different range other than the target range but sharper at low magnification.

      To answer the initial question, parallax only occurs if you have your eye in a different place behind the scope at ranges other than for which the scope is set (made) to be parallax -free. You could shoot just as accurately at any range if your eye is in EXACTLY the same place for each shot with out need to adjust for parallax, assuming the image you see is sharp.

      Many scopes do not have parallax correction (adjustable objectives) and accurate shooting is still done with them over various distances. This illustrates the importance of gun fit and a consistent technique.
      This post may be fact or opinion, it is up to you to decide which.

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        Originally posted by TwoFourThree" post=43638
        Parallax is defined as the apparent movement of one object in relation to another by a change in position of the observer.

        We say 'apparent movement' as if the observer is moving (or in different positions for each observation) and is unaware of his movement then he can believe that of two stationary objects, one or both of them is moving.

        For scopes, the eye is the observer, and the reticle (image) and the target (image) are the two objects.

        What this means in relation to riflescopes is that if the image of the target is not in the same plane as the reticle (crosshairs) within the scope then the condition known as parallax exists. Optically speaking Scopes can only be parallax-free at one range.
        Parallax correction is not focus but appears that way to the human eye when high magnifications are used.
        Adjustable objective scopes allow for the image of the target to be moved into the same plane as the reticle. This is why images appear blurred at high magnification when the AO is set to a different range other than the target range but sharper at low magnification.

        To answer the initial question, parallax only occurs if you have your eye in a different place behind the scope at ranges other than for which the scope is set (made) to be parallax -free. You could shoot just as accurately at any range if your eye is in EXACTLY the same place for each shot with out need to adjust for parallax, assuming the image you see is sharp.

        Many scopes do not have parallax correction (adjustable objectives) and accurate shooting is still done with them over various distances. This illustrates the importance of gun fit and a consistent technique.

        The only time my scope has been on a plane is when it shipped from the States.

    • #6
      With a 1X red dot you don't have to lose any sleep over it....parallax free. Red dot on target, no matter where it is to you when looking through the scope and shoot.....as long as it's on the target, zeroed properly....it's all good.
      I'm in love with Jennifer Hawkins and Alessandra Ambrosio

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      • #7
        This article was written on another site and is credited to Paul Coburn. I thought it made for interesting reading.


        "I've answered questions about scope parallax about 300 times, and it's always a long drawn out thing, going several e-mails, and a few phone calls. It doesn't seem to make any difference how long the guy has been shooting, this one always keep screwing guys up.
        OK... here goes (Whew, this is gonna be a long one).
        There are several things that go on inside a scope, and in the eyes at the same time. Some of them worki against each other.
        But some terminology first... and we'll leave out lenses that are there to correct some optical or color errors, but don't have anything to do with image forming.
        We'll start at the front of it all, and work back.
        1 - The "Object"... the thing that you are looking (shooting) at.
        2 - The "Objective". The front lens is called the "Objective"... it forms the first image of the "object" we are looking at (that why they call it the Objective
        It is the lens that "captures" all the light, that is solely responsible for the image quality of the scope... if it is poor, you can't fix the poor image later.
        This lens is usually made of two different types of glasses (called "elements") sandwiched together, and is called an "Achromat".
        The Achromat is fully color corrected for blue and green. The red wavelengths are partially corrected, but have what is called "residual color errors".
        This is the normal type of objective used in shooting and spotting scopes. In quality, they can vary from badd, through sorta OK, to pretty damn good.
        If one of the elements is made of an "ED" glass, or a "Fluorite" (CaF) glass, the two element lens can be very good to friggin' outstanding.
        In some instances, objective lenses are made of three elements, and all three colors (blue, green, and red) are completely corrected. This type of lens is called an "Apochromat", and this is the finest lens that can be bought. The best of these can also have "ED" glass, or Fluorite as one of the elements.
        3 - The "First image plane". The Objective focuses the light to make an image of the subject, just like a camera lens. This image is upside down, and right/left reversed. This is the first image plane, but NOT the "First image plane" that is talked about when shooters talk about reticles.
        4 - The "Erector lens"... (if it is a group of lenses, it is called the "Erector cell"). Because the first image is upside down/wrong way around, we (as shooters) can't use it... so we flip it around with a simple optical group called the "erector cell". This cell gives us a new image that is right way around, called the second image plane. Moving this cell causes this second image plane to move... so micrometer spindles are put against the cell, to get elevation and windage adjustments.
        5 - The "Second image plane". This is the second real image plane in the scope, and this is the image plane that shooters call the "First image plane" when talking about reticles. In a fixed power scope, or in a variable with a "First image plane reticle", the reticle would be placed in this image plane.
        This is where Premier Reticle puts those magical "Gen II" reticles.
        6 - The "Zoom group". In a variable scope with standard (non-magnifying) reticle, the zoom group of optics would follow #5. This group of lenses can change the size of the image plane in #5 and then form a new (third) image plane behind it.
        7 - The "Third image plane" In variable power scopes, this is the plane that the reticle is placed in. By being here, it allows the image to change sizes, but the reticle to stay the same size. In the context of reticles, this is the image plane that is referred to as the "second image plane"
        8 - The "Eyepiece". This optical group is like a jewelers loupe. Is is (or should be) a super fine magnifier. It's only job in the whole world, is to focus on the reticle.
        Let me repeat that for those that live in Rio Linda...
        THE ONLY JOB FOR THE EYEPIECE IS TO FOCUS YOUR EYE ON THE RETICLE!!!!
        It CANNOT adjust, or compensate for, or do anything else when things look bad in the scope, or when you can't hit the target... and you CANNOT use the eyepiece to try to correct for parallax. That is sheer folly at best, and raw stupidity at worst.
        If you expect it to do anything else, then stop wasting your time with long-range shooting, cuz you are never gonna make it past mediocre... and take up golf!!
        OK... now that you know what the insides are like... lets move on. We'll use the zoom scope for our examples. cuz if you can understand the zoom scope, then the fixed scope is a walk in the park.
        In the scope that is set for infinity range, the object forms an image behind the objective (the first image plane)... the erector cell "sees" that image, and flips it over and makes it right way around in a NEW image plane (the Second image plane). The zoom group adjusts the size of this image plane, and makes a NEW image plane (the Third image plane) that is the desired size. There is a reticle placed in this last image plane, and the eyepiece focuses on the reticle AND the image at the same time.
        When things are good, that's how the scope workie!
        ---
        But... now the booger falls into the soup... IF the third image plane and the reticle are not exactly, (and I mean EX-ACT-LY) in the same place, then your eye cannot see them LOCKED together as one picture.
        It sees them as two separate pictures, and the eye will look at each separately, and the eye can also look AROUND one to see the other.
        ---
        Lenses are measured in metrics (aka Millimeters). Not because the Europeans wanted the metric system 20 years ago, but because optical strings and chains of lenses (like scopes) are really a string of numbers.
        There are constant ratios of "this divided by that's" that give image sizes, "F-ratios", and image locations. It's so damn easy to do the engineering using a 10 based system that the optical guys were using the metric system way back in the 1800's.
        The objective has a "Focal length"... this is the distance behind the lens that the first image plane falls when making an image if a subject that is at infinity (or very damn far away).
        If the objective has a focal length of 100mm, then the image of that 1000 yd target is 100mm behind the lense.
        But the problem with geometric optics (which is what we are dealing with here), is that they follow the laws of geometry... and optics make triangles like rabbits make babies.
        AND... in an optical chain, when you change one thing, one angle, one ANYTHING, everything else follows along and changes BASED on the ratios involved at THAT stage.
        If we take that same target, and move it to 100 yds, the image in the scope moves BACKWARDS, going further into the scope. Not by much, but it doesn't take much, cuz we're dealing with very small distances inside the scope, and very high magnifications.
        How far the image moves back, and what it's new position is, is predictable by the mathematical ratios of the angles formed by the subject and the first image... OR (for us dummies that lost our slip sticks) by the ratio of the distances to the Target and the focal length, multiplied by the focal length. then ADDED to the focal length.
        The target is at 100 yds (91440mm), the focal length of the objective is 100, so the displacement is 1/914 x 100, which means that the first image is now at ~100.1mm. Hmmm only .1mm, that doesn't seem like much.
        Read the following paragraph twice...
        In a 1x scope, 0.1mm would mean nothing... but this displacement is repeated throughout the chain, AND if any of the optical groups change the image ratio (aka image size), then the displacement (aka ERROR) is changed in direct proportion to the increase in magnification. So in a 3x scope, it would be .3mm, and in a 10x scope, it would be 1mm, and in a 30 power scope, the image would be 3mm behind the reticle.
        Now, you should have seen a pattern in this last paragraph.
        READ THIS TWICE!!
        With the same error in the objective (scope focused at 1000, and target at 100), the parallax INCREASES WITH MAGNIFICATION... got it?
        If not, READ IT TWO MORE TIMES!!
        OK... now, if we do the same math for closer distances, like 50 yds, and 25 yds we will see that the error gets really big, so that with a target at 50 yards, and the scope set at 35 or 65 yds, the parallax makes the combination un-usable.
        ---
        Parallax is... when the image of the target, and the reticle, are NOT in exactly the same plane, and by moving the eye up and down... or side to side, either the target OR the reticle appears to move in relation to the other.
        You might see the target move and the reticle stay still, or you might see the target stay still and the reticle move over it... both are exactly the same, and which you see, is only a matter of your OWN perception.
        It is NOT possible to have parallax while moving up and down, but not have it when you are moving side to side.
        If you think that is what you have, you have other problems... either you are moving the rifle, or you have eye problems.
        ---
        HOW TO SET UP A SCOPE!
        This is the only way to do it...
        First, screw the eyepiece out (CCW) all the way, until it stops.
        If you wear glasses, put them on.
        Hold the scope up and look OVER the scope at the sky, and relax your eyes. Then move the scope in front of your eye.
        The reticle should look fuzzy
        Turn the eyepiece in 1/2 turn, and do the same thing again. You will have to do for a while before the reticle starts to look better. When you start getting close, then turn the eyepiece 1/4 turn each time.
        Do this until the reticle is fully sharp and fully BLACK immediately when you look through the scope.
        Than back off one turn and do it again to make sure you are in the same place.
        Then LOCK the ring on the eyepiece, and leave it alone forever!
        Second.
        Set the scope down on something sold, where it can see something at a long distance... half a mile of longer is good.
        It can be on the rifle, and rested in sand bags at the range... but pick something at least 1000 yds away... even further if possible.
        If the scope has an "AO" Adjustable objective, then set it for infinity, and look at the distant object, and move your head from one side to the other, or up and down if you prefer.
        If the reticle seems to move, there is parallax.
        Change the distance setting and try again... if you are very careful, you can move your eye, and adjust the distance at the same time, seeing which direction gets better.
        With front objective adjustments, you can turn them either way without worry... BUT with side adjustment scopes, like the MK4-M3, the M3-LR, or the other LR family of scopes, the adjustment must ALWAYS be made from the infinity end of the dial. Turn the adjustment all the way until it stops (past infinity), and then start turning it in a little at a time, until there is no parallax. If you "overshoot" the proper setting, you can't just turn back a little, you must go back to stop at the end of the dial, and start over again.
        While "AO"s dials are locked in place, and if the indicated distance doesn't match the real distance, there's nothing you can do about it... the side focus dials are not locked in place.
        Once you have found the setting for infinity on the side focus models, then (CAREFULLY) loosen the screws, and set the dial so that little sideways infinity symbol is lined up with the hash mark, so it is calibrated. You can also make little marks or put on a paper tape for other ranges instead of using the round dots that don't match any range.
        Now you can set it to infinity, but remember that you MUST turn the dial all the way past infinity to the stop, EVERY TIME before going from a close range to a longer range.
        If you are set for 500 yds, you can go directly to 100 yds, but if you are set for 100 and want to set it to 500, you MUST go all the way back to the stop, and then go to 500
        This is because there is a fair amount of backlash (aka SLOP) in this wheel linkage to the focusing cell, so you can set it only from one direction to make sure the slop is always on one side. The other problem with it is, even if you decided that you wanted to calibrate from the other end... the recoil will push the cell back. SO you must ALWAYS set these dials from the infinity end of their scales.
        To make it easy to not have to remember... I always start from the end stop, when I change range, no matter which direction I'm going in... it adds about 0.023 seconds!
        ---
        Now... you got a friend that says to set up a scope a different way???... he don't know doodly-squat about scopes.
        The guy at the range said to do it a different way... he don't know either.
        You know some guy who's in the Marines says to use your eyepiece to correct parallax... he doesn't know about optics either.
        You got a friend that shoots benchrest and says something different... he don't know crapola!
        This is the way, the only way, there is no other way.
        ... as Rushbo would say... this is from GOD-da .
        You gots questions, just e-mail me.
        You wanna "debate it", then go play golf, cuz you're wasting my time!
        'lito (gettin' grumpy in my old age!)"

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        • #8
          DocHollowPoint,

          Very good information and spot on.

          Did not know the bit about going back to infinity to correct for parallax in a side adjustment scope when changing ranges.

          You learn something new every day.

          Someone ought to 'sticky' that article somewhere on the forum.


          TinyTim,
          I think I see what your optronic technician may have been talking about .
          Don't know how a sighting system for a challenger 2 tank works, but with that level of accuracy I would like one on my .243. Bet it won't fit though.
          This post may be fact or opinion, it is up to you to decide which.

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            Originally posted by TwoFourThree" post=43776
            DocHollowPoint,

            Very good information and spot on.

            Did not know the bit about going back to infinity to correct for parallax in a side adjustment scope when changing ranges.

            You learn something new every day.

            Someone ought to 'sticky' that article somewhere on the forum.


            TinyTim,
            I think I see what your optronic technician may have been talking about .
            Don't know how a sighting system for a challenger 2 tank works, but with that level of accuracy I would like one on my .243. Bet it won't fit though.
            I'm pretty sure he was using short words just for me

        • #9
          Parallax means nothing when using Aimpoint optics.....there isn't any.....made in Sweden.

          I'm in love with Jennifer Hawkins and Alessandra Ambrosio

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          • #10
            Something I do to assist alignment, I can see a blurry image of my front sight in the scope and I move things around to get the crosshairs in the middle of the front blade. It seems to help and is at least one thing I can keep an eye on re alignment. And I think it helps to use click adjustments for distance rather than hold over, as your looking down through to scope which can distort things a bit.

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            • #11
              Parallax isn't important for hunting, probably more important for shooting small groups at diff ranges.
              Whacking Varmints is my passion!

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                Originally posted by Varminator" post=44605
                Parallax isn't important for hunting, probably more important for shooting small groups at diff ranges.
                Im more of a target guy, so i think im goingt o have to get a refund for my scope lucky i didnt open it.

            • #12
              so is the answer to get an AO every time - will that help?

              I'm about to buy a scope for a .17HMR and was about to pull the trigger on a Nikon without an AO and parallax set at 100m.

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              • #13
                http://www.youtube.com/watch?v=JrFj2zR0mdI
                Whacking Varmints is my passion!

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                  Thanks varminater, thats a great vid.
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