|MadSci Network: Physics|
My son has a BB gun with a "tubeless red dot sight" on it. He asked me how it worked, and after much thought, I'm still not sure. Basically, the sight works by having the light from a rearwardly-situated LED projected onto a lens. Once the sight is zeroed in (by way of a movable base), wherever the red dot is viewed by the shooter is where the point of impact of the BB will occur. What is curious is that if one's head moves while viewing the dot, it will appear on a different part of the lens (i.e. closer to the edge or the center), yet it will still be aligned with the same area of the target. I'm told this type of sight is known as a "reflex sight" and works similar to an SLR camera or certain sighting devices in astronomy. Here are my questions: 1) How is it that the dot always appears visible in relation to the target? 2) Why does the dot appear at infinity, suspended over the target, instead of just a couple feet from the viewer's eye? Any explanations you could provide us with would be greatly appreciated. Thank you, Mark Burton
Re: How does the dot in red-dot gunsight appear visible relative to the target?
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