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scope focus problem Burris

freddbear4
I have a 8X32 burris signature scope that blurs the field at higher power settings. eyepiece is adjusted so crosshairs are crisp and clear. parralax was set at 400 yds, where I was shooting, but when I tried to raise the power level to the max (32) the entire background becomes blurey starting at around the 20 power level. ??? any help or suggestions would be appreciated.
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10 comments

Date Votes
  • tsr1965
    freddbear4,


    The settings for the parralax are only calculations, and a lot of things come into play besides parrallax. I am guessing what you were seeing is what we call mirage from the heat. Had you been firing the gun, and puting ANY heat in the barrel? If so, try putting a large piece of card board between the barrel and scope, and see if it is still there.

    Best
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  • Tailgunner1954
    You set your high magnafication (objective) focus on the target at 400yd, and can't figgure out why objects at 425+yd are out of focus?
    As my buddies kid would say, DUH
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  • ern98
    If all else fails send it back to Burris. The last time I had a problem with one of their scopes they didn't even charge me for the return shipping. They didn't even ask if I was the original buyer.
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  • wpage
    Why not contact burris for a user manual.
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  • Don McManus
    quote:Originally posted by freddbear4
    I have a 8X32 burris signature scope that blurs the field at higher power settings. eyepiece is adjusted so crosshairs are crisp and clear. parralax was set at 400 yds, where I was shooting, but when I tried to raise the power level to the max (32) the entire background becomes blurey starting at around the 20 power level. ??? any help or suggestions would be appreciated.

    Is your target still in focus?

    If so, tailgunner has pointed you in the right direction, though perhaps in a less than helpful manner.

    As you increase the magnification, you will find that the depth of field (don't know the technical term) that is in focus will shorten. There is probably a formula for this, but I would assume that the depth of field that is in focus varies inversely proportional to the power setting on the scope.

    Don



    EDIT: Curiosity kills time, if not the cat.

    http://en.wikipedia.org/wiki/Depth_of_field

    For a given format size, at moderate subject distances, DOF is approximately determined by the subject magnification and the lens f-number. For a given f-number, increasing the magnification, either by moving closer to the subject or using a lens of greater focal length, decreases the DOF; decreasing magnification increases DOF. For a given subject magnification, increasing the f-number (decreasing the aperture diameter) increases the DOF; decreasing f-number decreases DOF.

    Obviously a discussion about cameras, but optics is optics.
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  • tsr1965
    quote:Originally posted by wpage
    Why not contact burris for a user manual.


    Because if you can read this column, or post here, you can get it quicker than talking to them and having them send it.
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  • freddbear4
    It was a heat mirage. Combo from the barrel and surface temps (95+). As for tailgunners response-- WOW, would not have expected that from an expert.
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  • mrbruce
    Heat and humidity will cause a haze that is easily seen with any scope on high power, usually dialing it down to a lower setting will decrease the problem..
    Nothing like shooting on a nice cool crisp day when the haze is long gone...
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  • JustC
    mirage is a b!t(h, but dialing back the magnification will resolve that issue (no pun intended)
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  • freddbear4
    Thanks to all that responded. Noted, if targets become blurry, dial down and continue to hunt. South Dakota was hot and windy and be sure you use bug spray for chiggers that you won't feel biting but may be ever present. Thanks again.
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