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Thread: Parallax

  1. #1
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    Default Parallax

    Hi guys, there is an article in January 2008 Airgun World about Parallax.
    See in a recent post here, that someone mentioned using a small card to help reduce parallax errors. Since parallax only occurs if your eye is not dead centre, on the line of sight to the target, through the centre of the reticle, reducing the chance of error by reducing the size of the exit pupil, this should work, but is it allowed. Except maybe for training. Has anyone tried it? Any other ideas to reduce parallax errors....
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  2. #2
    Sharp Shooter
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    Hi Tomcat.. the post I saw was about using the card on the objective bell not the rear. Anyways.. Cant see it being illegal.. only problem is that you cut down on the light entering the scope thus this will not work in low light.. Anyways the groupings doing this looked very promising
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  3. #3
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    According to the article in the mag, the exit pupil is (objective size)/4,and the smaller the exit pupil the less chance of parallax errors. So your comment makes sense. Means if you have a 50mm objective and cut a card with say 32mm hole and stick it over the front, you should have better results. Question to the powers that be "Is it legal".
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  4. #4
    Sharp Shooter
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    the holes I saw inthe card wa more like 5-10mm. And yes I would also loke to knowthe legality asthiscould make HFT a breeze.
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  5. #5
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    Read through the current rules and did not see anything that implies you cannot do it. As long as you start with it on and don't change it in any way during the shoot. Going to give it a try soon as I get a gap over the next few days.
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  6. #6
    REP: Air Rifle Pros

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    A simple rule of thumb to determine exit pupil size is objective bell diameter divided by the magnification that the scope is set at ie. 50mm Objective scope set at 10 X magnification = 5mm exit pupil.
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  7. #7
    Sharp Shooter
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    What is this BS all about.....????
    If you put such a small aperture over the front lens, how are you going to get enough light in to see the target.....????
    As it is it is difficult to see a reducer in the shade at 8m distance....., even by using a 42mm Objective scope.....!!!!

    malan
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  8. #8
    Sharp Shooter
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    lol. true malan but I have seem the pics of test runs like that. And I have to say the groupings look impressive.. granted the more you shoot with a scope/rifle combo the less you will need it as you will naturally learn to have the same position over and over again.
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  9. #9
    Marksman
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    Malan it's not BS...it's about depth of field for HFT...think photography??
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  10. #10
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    Hey, that's what I wanted to say....
    Like Guido said, think photography as the aperture affects your depth of field.
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  11. #11
    Sharp Shooter

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    "The objective opening aperture of the scope must be left as it was manufactured and can not be reduced in any way to increase the depth of field, All types of scope caps must always be in an open position when taking a shot."


    It is illegal for HFT according to the uk rules. It increases the depth of field meaning that the target will be in focus for a greater distance without adjusting your parallax. I do not know if it would help with parallax error though???
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  12. #12
    Sharp Shooter
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    mmm.. that is interesting.. why dont the manufacturers manufacter a hft scope. I understand the typical size on the objective bell is to increase the field of view(and to let in more light) but when shooting target you do not need a large field of view unlike when you hunt. So you should have a 10x10 scope for hft and you will be very compettative as you will be reducing the parallax as far as possible.. do one get scopes like that?
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  13. #13
    Sharp Shooter
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    I also know enough of photography to know that it does not apply to the parallax problem you encounter when shooting at one fixed objective setting at various distances......
    The thread that TomCat and JTK refer to can be found on the Yellow Forum ARCHIVE posts of the month..... http://www.network54.com/Forum/79537/thread/1136083458
    The article describes briefly how to set up a scope by using gravity and a close focus to obtain some sort of alignment.... I dare anyone with enough sense to even try and hit a target at, say 35m with a setup like that, by using a 5mm hole on the front lens and still have enough light to reach the eye and be able to see the crosshairs.....!!!! So come on man, show us the results......?????

    malan
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  14. #14
    Sharp Shooter
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    Hi Malan.. I must aggree that I did not try it and will do that 1st up before I make further comment.. The explination just picture just seemed very convincing
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  15. #15
    Sharp Shooter
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    JTK
    Apology accepted, my friend.... The main reason why things in the telescope world changed dramatically, was when they moved away from the old pencil scopes with objective lenses of not more than 12mm to todays marvels of 50 and even 60mm lenses, giving you as much light as possible through to the eye.....
    What would be interesting, is if we had to go back to these (antique) scopes and mount them on today's air rifles...., that would be a challenge, surely.... But then I suppose there would be another rule against that as well........????

    malan
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