Roger Bailey wrote: > I tried your Shadow Sharpener test today and was amazed at the result.
Me, too! It was easy, just using the shadows falling on my desk. My pinhole was made by sticking a paper clip through a Post-It, which I stuck to the edge of a clip board on my window sill. The gnomon was first a seam down the middle of the window, then I changed to another Post-It stuck to the window so I could adjust the width of the shadow. With the image of the gnomon a bit smaller than the image of the sun, I watched the brightness of the spots on each side where the sun was shining through. There was only about a two second interval when they looked balanced. That means even a quick and dirty set-up can yield an accuracy approaching +/- 1 sec! (I am in San Diego near midday, so the shadows may be running a bit faster than usual.) --Art Carlson
