> 107:1 seems to be the ratio between the projection distance from a
> pinhole to a screen and the diameter of the Sun's image. That is, the
> diameter of the Sun's image will be about 1/107th of the distance
> from the projecting pinhole.
>
> Since a pinhole image is very dim, for brighter images, the ratio
> between the projection distance and the hole diameter is recommended
> as ranging from about 200:1 to 400:1.
>
> Hope this helps.
>
> Mac
Isn't that reversed, Mac? If the image is too dim, you would want a larger
pinhole, not a smaller one, as 200:1 or 400:1 would indicate...
Dave
Hi Dave,
Not reversed, just very poorly worded. I was trying to say this:
Since a pinhole is very small, the image is very dim. For brighter
images a bigger aperture is used, and the ratio between the
projection distance and the hole diameter is recommended as ranging
from about 200:1 to 400:1.
If you use a pinhole with a diameter of 0.01 inches, this means a
projection distance of 2 to 4 inches, and the image is bright, but
too small.
For a 1/4 inch hole, a projection distance of 50 to 100 inches works well.
If the projection distance is too short relative to hole size, you
get an image of the hole, not of the sun. I don't recall the ratio at
which the changeover takes place.
Sorry for any confusion. Hope I've got it clearly and correctly
stated this time around.
Mac
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