How clear is your scope?

Discussion in 'Long Range Scopes and Other Optics' started by freebird63, Sep 25, 2011.

  1. freebird63

    freebird63 Well-Known Member

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    I have a 280AI, I have a 20 moa nightforce rail and nightforce rings, the scope is a sightron S3 6-24X50 with the mil-dot reticle. I have always loved sightron scopes. I have heard some people talk about how far out they can see the bullet holes in their targets and it seems like its a whole lot farther then I can see my bullets holes, about 200 yards is the limit and thats with no mirage from the sun. I can't remember where I read it but some nightforce owners have claimed to be able to see their bullets holes out to 1000 yards, that seems like a long ways to be able to see your bullet holes. Has anyone else ever heard this???? Not that I am in the position to go out and buy a new scope. I have found being disabled has really cut into get toys.
    Anyone have any input on the subject??
    Thanks
     
  2. LouBoyd

    LouBoyd Well-Known Member

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    Probably the biggest factor in being able to detect bullet holes in a target is how the target is illuminated. A normal naked human eye can resolve two points of light separated in angle by about one minute of arc. 1 MOA at 1000 yards is roughly 10 inches. with a 20x scope you should theoretically be able to see two bullet holes that are 1/2" apart. Bullet holes are generally 1/4" to 1/2" diameter depending on the caliber you shoot. At 1000 yards bullet holes are rarely resolved as round disks. They are only a a darkening or lighting of the surface brightness relative to the target face. Eyes detect light. They don't detect dark. You only see a dark bullet hole if by the reduction of lilght relative to the light around it, and for an area which is too small to resolve a dark spot is much more difficult to see than a light one. If you want to see bullet holes easily at 1000 yards use a dark colored target and orient it so the sun is not shining on the face of the target but so the sun is shining on a light colored backstop behind the target. Bullet holes will be bright on a dark background and will be much easier to see than if they're black on white background or black on a black background.

    The atmosphere never makes a target easier to see. The main causes are:
    Scintillation, aka mirage, which is caused by non-uniformly heated air. It's usually caused by the sun heating the air at the ground/air interface and that hot air rising through the cooler air above.
    The light cone (the part of the light which will form an image in your eye) from a bullet hole will be the diameter of bullet at the target and the diameter of the scope objective at the shooters location. The differential refraction the air in between bends the direction the light travels within that cone which scrambles and increases the apparent size of the image. The motion of the scrambled image contains information about the distance and velocity of the wind moving the heated air cells.
    With a lot of practice good shooters can use that information to predict how the wind will affect the bullet point of impact. That's a lot more important to accurate shooting than seeing the bullet holes.
    Mirage is the friend of a skilled shooter.

    The other main causes are absorption and scattering. Particulates in the air can be dust, smoke, pollen or water droplets. For the light coming from the target to the scope the effect is mostly just to reduce the light by absorbing it or scattering it away from the line of sight. The bigger effect is that it scatters sunlight some of which will be in the same path and direction of the light you're trying to see. The effect is loss of contrast and washing out the light from the target.

    When the two above are combined seeing a dark bullet hole on any background becomes impossible. The brand (or cost) of the scope makes very little difference.

    For less than the cost of a good spotting scope you can use a laptop computer, an internet webcam, and two wireless APs with antennas. It will run all day on a car battery. Set the camera 20 feet in front of the target (a little to one side so you don't shoot the camera) and you can easily see bullet holes at a mile on the screen of your laptop in real time.

    Being able to see bullet holes is useful for sighting in rifles and working up loads. Maybe in some forms of target shooting. It has little use for hunting.
     
    Last edited: Sep 26, 2011

  3. Loner

    Loner Well-Known Member

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    here is an 80x march. You make up your own mind.

    [ame=http://www.youtube.com/watch?v=03qtXpoObfM&feature=related]1000 yds Benchrest - YouTube[/ame]

    They may be referring to the 3 inch marker discs placed in the bullet holes.
     
    Last edited: Sep 27, 2011
  4. freebird63

    freebird63 Well-Known Member

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    Wow, ah ya my scope does not even compare to that one. I am sure that scope cost more then my scope & rifle. Ya that type of shooting I couldn't do as it takes me too long to finally get the target to quit moving.