joe_meadmaker wrote on Nov 8^th, 2021 at 10:41pm:

I'm thinking that if the projectile hits within the circumference of the coin, then it counts. Lets say the projectile hits the top of the stake where the coin is attached, if the projectile would have hit the coin (imagine the coin floating in mid-air) then it counts.

There would also have to be a rule regarding projectile size e.g. no bigger than a tennis ball, for example.

A 4th option could be to put the camera downrange behind a tree or other large obstruction, and turned at an angle so it's facing the target.  If there's a barrier in front of your camera, it won't get hit.  The only problem with this is the barrier will also block the slinger from being in the recording.  So only the actual target hit will be on camera.

Sorry for the size, but if it's shrunk you won't be able to see the coin.

Sarosh wrote on Nov 11^th, 2021 at 3:06pm:

Yes I think the sun was a bit to the left of the brightest part of the sky. The coin was propped up so that it was facing me almost square on (it may have been very slightly tilted back). I have a few more photos.

Well… you can see “something shiny” but if you didn’t already know that coin was there, you wouldn’t be able to identify the target… especially if there are other reflective objects in the environment.

There seems to be a specific need in this case for a more pedantic definition of “see”.

If you look up the resolving power of the human eye, it is  about 20 arcsec (from the diffraction limit and the size of the aperture of the human eye, i.e. pupil.) but it is less in actuality due to eye aberrations.  But if we assume 20 arcsec, that's about 2.8e-4° or 9.7e-5 radians.  Using the approximation sin(theta)=theta (i.e. object radius/distance = theta), you can calculate the size of the object that one should be able to see.

So for a 1" coin, --> r=1.27cm, solve for distance, ~13092cm, or 130m.  That is a best case scenario if you had absolutely perfect eyes. It will be much less than that in practice, depending on your eyes, likely 1/2 or a 1/3 of that.

For something that is shiny and that diffusely reflects light, you will be able to make it out just from the reflection, but you won't actually be able to resolve it (i.e make out the shape). You'll only be limited in distance by how low of light intensity you can detect (as the light intensity will fall off 1/r^2). I think that is what you were detecting was the diffusely scattered light from the coin.

IronGoober wrote on Nov 12^th, 2021 at 12:24pm:


40m seems like a sufficient challenge especially considering that the modern competitive definition of a “good shot” is a 50cm Diana at 20m.