Tube diamiter?

Discussion in 'Long Range Scopes and Other Optics' started by kc, Mar 28, 2012.

  1. kc

    kc Well-Known Member

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    Is a 30mm diamiter better than a one inch diamiter?
     
  2. mackgee

    mackgee Well-Known Member

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    The way I understand it, the only thing you gain from the 30mm tubes is you have more windage and elevation adjustment than you get with the 1 inch scopes. Other than that you don't gain anything else.

    Mac
     

  3. nratom

    nratom Member

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    That's the way I also understand. Light gathering is not better with the same objective size.
     
  4. bruce_ventura

    bruce_ventura Well-Known Member

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    To get 6X zoom range, I think you need to go to 30 mm.
     
  5. LouBoyd

    LouBoyd Well-Known Member

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    That appears to be true, but I'd bet it's more driven by marketing than optical design necessity.
     
  6. bruce_ventura

    bruce_ventura Well-Known Member

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    Read recently that the reason is mechanical. A 6X magnification range requires that lenses in the erector tube move further than for a 4X range. The power ring translates lenses via helical slots.

    A single rotation of the power ring on a 1" tube cannot move lenses far enough for 6X. The helix angle in the translation mechanism would be too steep, requiring excessive torque. The same rotation of the power ring on a 30 mm tube can, however.
     
  7. Max Heat

    Max Heat Well-Known Member

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    The terms 4X and 6X are not really proper, in this context. It would be more proper to state it in terms of power adjustability (zoom) RATIO, as in 4:1 or 6:1.
     
  8. FEENIX

    FEENIX Well-Known Member

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    ... or simply X4 and X6! lightbulb

    However, everyone seems to know exactly what it meant and responded accordingly.
     
  9. Max Heat

    Max Heat Well-Known Member

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    That looks better I guess, being that it does not have the same appearance as magnification level. I'm not any sort of expert in optics or anything. In hindsight, I should have let it ride. What I just realized though, is that the magnification level itself is also a ratio. Only difference is that it is set "over" 1, instead of "to" 1.
     
  10. davewilson

    davewilson Well-Known Member

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    i have a scope ordered that has a 10x zoom range, it's a 30mm. the 30mm tubes are basically much stronger . most have thicker side walls and the bigger diameter helps too.
     
  11. Max Heat

    Max Heat Well-Known Member

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    Out of curiosity, what is the zoom range and objective size on that scope?
     
  12. davewilson

    davewilson Well-Known Member

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    2.5-25 with a 42 bell
     
  13. Colorado Cruiser

    Colorado Cruiser Active Member

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    If all of the above is true, why does vortex use a 34mm tube in the razor and it is a 4X (5x to 20x)? Maybe light transmission??
     
  14. bruce_ventura

    bruce_ventura Well-Known Member

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    It's actually a 35 mm tube. It gives a whopping 125 moa of reticle adjustment. I think it's all for product differentiation.