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Basic Optics Question

Discussion in 'Shooting Gear and Storage' started by Flynt, Nov 6, 2005.

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  1. Flynt

    Flynt Member

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    I'm trying to teach myself how to shoot with a scope, so this may be a pretty basic question. One thing I have noticed with binoculars and spotting scopes is that they have "minimum distance" for focusing, and it varies according to magnification. For example, when I set my spotting scope at 45X, a target at 100 yds. is a little too close for it to focus. I need to drop the magnification back to 35X or so.

    I have a couple of variable power rifle copes that also have a focus adustment. For example, I have a Leupoold with magnification ranging from 4.5 to 14, and a focusing knob with distances marked on it starting at 50 yards. Here's my question: Am I better off adjusting this scope to a less-than-maximum magnification -- say 9X -- at 100 yds or less? (I set the focus knob on 100 yds.) I'm wondering if cranking it up to 14X at 100 yds. creates parallax problems? Thanks.
     
  2. FPrice

    FPrice Member

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    Flynt...

    Some good questions which I do not have any answers to, but I am also curious.

    It would seem to me that the higher the magnification, the further out the minimum focusing distance would be. Of course this may vary from scope to scope.

    I have a similar question because I have a Swift Model 664M, 4-12x40, that has a front focus adjustment. I am trying to find out if in general such an arrangement is better than a scope without this adjustment.

    Optics seems to be the hardest subject to get help with on firearms forums. Maybe we can get some more people to join in and help us.
     
  3. LHB1

    LHB1 Member

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    Flynt,
    I prefer to use 4-5X at distances less than 100 yds because it increases field of view (easier to find target) and doesn't magnify the wobble so much. Has worked fine for me for (too) many years. Suggest saving the high magnification settings for target work from bench rest.

    Power setting does not increase/decrease parallax altho you might see it better on high powers. Quote below is from Leupold Answer Guide:

    The Leupold Answer Guide

    What is Parallax?
    What is parallax? Parallax is essentially an optical illusion. It is the apparent movement of the target relative to the reticle when you move your eye away from the center point of the eyepiece. It occurs when the target does not fall on the same optical plane as the reticle. Maximum parallax occurs when your eye is at the very edge of the exit pupil. (Even in this unlikely event, our 4x hunting scope focused for 150 yards has a maximum error of only 8/10ths of an inch at 500 yards.) At short distances, the parallax effect does not affect accuracy. (Using the same 4x scope at 100 yards, the maximum error is less than 2/10ths of an inch.) It is also good to remember that, as long you are sighting straight through the middle of the scope, or close to it, parallax will have virtually no effect on accuracy in a hunting situation. For more information, please consult our list of "frequently asked questions" at www.leupold.com/tifaq.


    Good shooting and be safe.
    LB
     
  4. Mikul

    Mikul Member

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    The reason there is a focus ring on your Leupold is to correct for parallax. With your scope, when BOTH the reticle AND the target are in focus, there are no parallax issues.

    Yes, generally speaking, high-magnifications only magnifiy a miniscule wobble zone which puts you on an endless cycle of trying to correct for a wobble that isn't large enought to worry about. 4x at 100 yards is plenty of magnification as long as you can see the target clearly.
     
  5. bcochran

    bcochran Member

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    Not only is 4x good enough at 100 yards on your Leupold, you can do the following with a low power setting, as we have done in class:

    1. see into shadows under trees at high noon;
    2. see and hit moving and stationary targets at a laser measured 240 yards with only starlight illumination at 2 am;
    3. see 100 yards and do accurate shooting with just an impulse on a surefire handheld light behind the line and held towards the target.

    By the way, you aim dead center on a target when using a scope. None of that stuff about 6 o'clock holds.

    For the best education on optics, find a varmint hunter in your area. Until then, run out and laminate ballistic cards. You are about to shoot further and more accurately than you may have imagined. With Leupold 4.5x14, using a .308, I did dead center on the second shot at 900 yards. Without a scope, I cannot even see a DCM target at 600yards.:)
     
  6. Flynt

    Flynt Member

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    WoW! 4X!? That's a whole different way of thinking, at least for me. I'm from Texas, where bigger is always better, so I just assumed I'd shoot better with more magnification. I'll have to try it at 4.5x. Sounds like a completely different world. Thanks.
     
  7. LHB1

    LHB1 Member

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    Flynt,
    Many years ago I won several 200 yd offhand rifle matches at our club in Corpus Christi. After a while, some of the guys started looking at my equipment to see what I was doing. They discovered my secret! I set my 3-9 variable power scope on 3X for offhand shooting to minimize apparent wobble. This allowed me to still see target and squeeze trigger instead of jerking it. Worked for me.

    Good shooting and be safe.
    LB
     
  8. Flynt

    Flynt Member

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    LB, This is beginning to makse sense, but then I wonder, What's the purpose of the higher magnifications -- are they only good for extreme distances? Have the scope makers and retailers been selling most of us (who are presumably deer hunters) more scope than we really need?
     
  9. LHB1

    LHB1 Member

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    Flynt,
    IMHO magnifications higher than 6X are made for target shooters who need to see 1/32" size targets and AS A SELLING GIMMICK. Have you ever heard that fishing lures are really made to catch fishermen instead of fish? Well, there are those who will disagree with me but I think high magnification scopes are sucker traps for hunters! Give me a 1x4 or 2X7 for hunting and I will be perfectly happy. For sub-minute of angle target work, I would like a fixed 10x scope with focus and parallax adjustment. YMMV

    Good shooting and be safe.
    LB
     
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