And hold it 3 feet off the ground, what shape will the light spot within the shadow be?
Also, what if the sides of the triangle were 1/8 inch each?
Hint:
http://cac.uvi.edu/staff/rc3/astro/safesun.html
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I should have said pinhole.
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More Pages:
- Solar Lights: Solar Eclipses Appear As Cresent Shaped Spots Of Light On The Ground Beneath Trees. The Small Opening Between? (5/29/2011)
- Solar Products: Is It Bad To Looked Straight Up To A Solar Eclipse Without Any Gadget At All?? (6/8/2011)
- Solar Lights: Designing 3d Solar Panels? (6/16/2011)
- Solar Lights: Gardeners Have You Bought Any Solar? (6/11/2011)
- Solar Products: Is There Research Or Products For Solar Power To Lighting? (5/22/2011)
{ 2 comments… read them below or add one }
Both the sun and the moon have an angular diameter of 1 in 120, so that if there was but a pinhole in the cardboard, the image 36 inches away would be 36/120 = 0.3 inches. If a triangle shaped hole is used instead of a pinhole, then you can imagine that for every point of light in the first image there will instead be a triangle shaped blob of light, the light intensity varying in proportion to the light intensity of the original point (small disk, actually) of light. So, if you use a small 1/4″ triangle, the image of a solar eclipse might still be discernible, however blurry. For a large 1″ triangle that is 3 times larger than the original image, it will probably be just an unrecognizable wash.
In Fourier optics, this is known as image convolution, where the triangle aperture is the “kernel”, and the image is that of the ideal shot of a solar eclipse.
A much more interesting result can be had if you used a really dirty window screen clogged with dirt. Then with just the right kind of clogginess, you can have an image of a glittering “starfield” of tiny solar eclipses. I’ve actually done this, not with a dirty screen, but with a ragged piece of paper. This is still image convolution, but this time it is the image of the solar eclipse that is the kernel, while the dirty window screen is the “image”. The two are interchangeable.
Oh wow, Remo, that’s a cool shot. That’s exactly what I was talking about.
Scythian gave you the basic facts.
I was in first grade when I first saw an eclipse through a pinhole camera. I was impressed. Years later, I made my own when an eclipse covered part of the sun. Need to make that hole small. The rounder the better, but size not shape is the determining factor.
Here is a site on Wikipedia on pinhole cameras which is pretty cool. http://en.wikipedia.org/wiki/Pinhole_camera . Don’t miss the picture of pinhole cameras caused by tree leaves during an eclipse.
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Ha, ha. As I was writing this, Scyth wrote about dirty lenses and starfields. That is what the picture of the eclipse through the leaves is. Here is the direct site: http://en.wikipedia.org/wiki/Image:IMG_1650_zonsverduistering_Malta.JPG