Scope shift

Discussion in 'General Airgun Chat' started by nudge it just a little, Dec 6, 2018.

  1. nudge it just a little

    nudge it just a little Member

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    I still can't understand why these expensive scopes shift in temperature variation .
    With all the R&D into them and yet they still seem to have difficulty eradicating this.
    I understand the expansion and contraction in metals but surely there are hybrids that are able to withstand temperatures without adverse performance.
     
  2. garym

    garym Member

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    It is not just the metals used. The gas inside the scope is another variable.
     
  3. MikeSeago

    MikeSeago Active Member

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    Chances are that any alloys that resist temperature shift would be either far to expensive or would be difficult to machine to the tolerances required. Whatever the material the volumes vary from main tube to the more intricate mechanisms and therefore they will expand and contract at different rates.
    There are technical limits the manufacturers are pushing closer and closer to them to obtain a shift free scope.
    We can but hope one appears one day
     
  4. MikeSeago

    MikeSeago Active Member

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    Nitrogen is the normally used gas for filling scopes as it is inert and removes the possibility of water vapour forming on the inside of the scope but it expands at nearly same rate as air so gives no major advantage in the expansion stakes.
     
  5. AlexS

    AlexS Member

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    The glass of the lenses is affected too. The refraction is changing with temperature. There are glasses, that withthand it somewhat, but nowadys ED lenses are in vogue and they are even worse.
     

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