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Parallax, do you check it.

  • 17-01-2023 3:37pm
    Moderators, Sports Moderators Posts: 28,445 Mod ✭✭✭✭

    Was talking to a young lad down the road from me who was having a little trouble with his new rifle and scope. It's a rimfire and €200 scope and all is new.

    He was close to getting his zero but couldn't find that last 5% to give him consistent results. He also said when he zoomed in or out he lost what zero he had.

    My mind went to parallax so I got him to look through his scope and without touching or moving the rifle/scope got him to move his head left to right and up and down while monitoring the crosshairs. He said the crosshairs were "following" his head movement so then I knew it was parallax.

    With focus, eye relief, and AO adjustment we got it to a point where there was no, or no perceived, movement, of the crosshairs. He redone his zero, zoomed in and out and the groups were not only tighter but very consistent.

    Got me thinking, how many check this when mounting/zeroing a scope and how many know to check for it?

    Also are there other "simple" checks that get overlooked when zeroing a new rifle that you feel like kicking yourself for when you realise what it is?

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    Post edited by Cass on


  • Registered Users Posts: 117 ✭✭itisnotgrand

    Is it a LPVO? Or long range scope?

  • Moderators, Sports Moderators Posts: 28,445 Mod ✭✭✭✭Cass

    Long range. 6-24.

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    If you see a problem post use the report post function. Click on the three dots on the post, select "FLAG" & let a Moderator deal with it.

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  • Registered Users Posts: 6,594 ✭✭✭Feisar

    I used to set it to what the markings said or to focus but since I've got back at it properly the past couple of years I set it so there is no perceived movement at max magnification, even if I intend to shoot at lower mag. Other stuff to check is the focus at the back and making sure the scope is set up for the shooter in terms of position in the rings/on the rail. Basically I ask myself, could I fall asleep here with correct eye relief etc. I also make sure my rifle and scope are square. I use a light shining down the scope to project the ret on a wall and use a plumb line to make sure it's level. After that I'll tall target test it to make sure it is. This will also allow me to check the tracking of the adjustments in the scope.

    @Cass, it was either a post from yourself or a setup guide you posted that made me pay attention to parallax. I have to say it was a total game changer at the time.

    Post edited by Feisar on

    First they came for the socialists...

  • Registered Users Posts: 549 ✭✭✭JP22

    +1 on whats said so far.

    Also, lots of people are totally focused on Parallax and completely forget that scopes also come with an ocular adjustment for the eyes.

    Most targets are pretty bland at best and it can be hard to determine if the Parallax/Ocular adjustment is set correctly.

    I find using a target with writing on it helps greatly as it’s easy to determine if the text is clear or out of focus.

    Just my tuppence worth.


    Yes, I check everything regurlarly.

  • Registered Users Posts: 268 ✭✭keith s

    I think on some scopes (particularly cheaper scopes) focus and Parallax do not always match. When "focusing" a scope to the point you can read text, you should also test for parallax error (as per Cass's note above).

    I've used scopes in the past that were out of focus by the time parallax error was removed.

    Definitely, you should check the manual for eye relief on a scope and get it mounted to the point it is most comfortable. When looking through the scope, the black around the edges should all match and moving your head back and forward you should find the position where you get the most picture size.

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  • Registered Users Posts: 594 ✭✭✭slipperyox

    I always check parallax at every magnification, but am also mindful of checking gun cant when zeroing.

  • Registered Users Posts: 874 ✭✭✭zeissman

    All my scopes have side parallax adjustment and I always adjust it for whatever distance I'm shooting at. When fitting a new scope I always make sure the turrets are at the center of their travel then boresight the rifle to see if everything looks ok.

    I have seen a few cases where the reticle was way off to one side but swapping the rings around from front to back usually sorted it. I then adjust the diopter to get a nice clear image of the reticle. I would then adjust the scope for eye relief. If it's a vari power scope I would usually set it in the middle of the power range then I would move the scope back or forward until I got a nice clear image. I would do this from the positions I would be shooting from ie. Prone . Standing and sitting.

    Then I would make sure everything was level and tighten everything up to the correct torque values.

    I would then boresight the rifle and adjust accordingly.

  • Registered Users Posts: 38,970 ✭✭✭✭Mellor

    I think it's very easy thing to miss. And properly comes down to experience/knowledge.

    For years I was only familiar with shotguns. My first rifle had a simple scope (by choice) with no AO. I was aware that AO turrets existed and what it was for, but never needed to worry about it on mine. One day at the range I borrowed a club gun, shooting at 300yards. It had the same Vortex scope (or so I thought) at a higher mag. I just couldn't get the groups right, struggled to see the target clearly etc. I put it down to the scope not being focused well with my glasses. I was going to give up, and then I noticed the scope had adjustment at the objective. In was the AO model.

    Seems silly in hindsight. But the rifle was zero'd. I treated it as like my own setup, in error.

  • Registered Users Posts: 1,114 ✭✭✭Zxthinger

    On newly acquired scopes I always float by eye ball around the alignment and check to see if I’m getting and reticle movement against the background image.

    I have nearly 30 different scopes at this stage finding theM as interesting as the firearms that they were designed for.. LoThe worst unit was a fixed 8x56.. There was no parallax adjustment so I loosened the inner objective locking ring and turned the objective out until I had no parallax at 300yard.. I reckon that so was close to the infinity range at that point.. I retightened all and I was set..

    Some cheaper units have major distortions that are evident when you zoom or mooz and a shot saver is a great tool to test the repeatability of a scope without all the testing on paper..

    I use to bed every thing in epoxy but I have since decide to go to modular system for all and now I only use steel rails that are nearly welded to the receiver.

    in truth these rails could all be tried for squareness and parallel edges and thereafter any mounts could be set and hand lapped with a 1in or 30mm drift..

    This whole massive effort probably isn’t worth it all for factory ammo..

  • Registered Users Posts: 268 ✭✭keith s

    Fixed Parallax scopes are a lot of the time fixed at 100mtrs/yards - infinity. For anything under the fixed range (0-100mtrs for example), you need to lower down the zoom (I think to its lowest power, the lower the power the less Parallax error you get).

    For a fixed power AND fixed Parallax scope, I'm not sure who that works!?!

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  • Registered Users Posts: 1,114 ✭✭✭Zxthinger

    Fixed scopes are easily adjusted as I have detail in my last post..

  • Registered Users Posts: 38,970 ✭✭✭✭Mellor

    A Fixed power scope without parallax adjustment would also have parallax correction set for 100yards or similar.

    If somebody wanted a longer range set, see the post above