Thibaud Taudin-Chabot wrote:
That sundial is not 1 spot projected on the floor, but the whole
sundial pattern projected on the floor. On the floor you only need 1
readingmark, nothing more.
I understand; I mentioned it as an example of dark spots being projected
on the receiving surface,
That sundial is not 1 spot projected on the floor, but the whole sundial
pattern projected on the floor.
On the floor you only need 1 readingmark, nothing more.
But the shadow of a spot on a window will be very difficult to find on a
sunlit floor because the light of the sunlit floor is
On Sat, 6 Sep 2003, John Carmichael wrote:
We're also discussing what I call antiaperture gnomon sundials. These are
neat. Imagine a large clear pane of clear or light colored glass on a wall.
And on this glass is a small very dark dot. Instead of a hole in a wall
casting a beam of light,
On Sat, 6 Sep 2003, J. Tallman wrote:
Perhaps there is a good ratio to use for dot/disc size vs. distance to
the shadow field? Perhaps some of the list members know the answer to
this...
Jim
1/107 had stuck in my mind, and I made a quick test a few minutes ago. We
have near-horizontal
On Sat, 6 Sep 2003, Mac Oglesby wrote:
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
I have also considered using this type of arrangement (a dot on a
clear pane) for several projects in the past. I wonder just how big the
dot would have to be? I assume penumbral effects would be at play, and
the distance to the shadow receiving surface would probably be a factor
in
Hi Terry
That's a wonderful idea too: a poor man's terrazzo!
The original idea of the designing consultant was to have three separate
aperture gnomon interior sundials in the building on the east, south, and
west walls. (each dial would tell time/date for just a portion of the day)
They are
Hi John,
We're also discussing what I call antiaperture gnomon sundials. These are
neat. Imagine a large clear pane of clear or light colored glass on a wall.
And on this glass is a small very dark dot. Instead of a hole in a wall
casting a beam of light, the dark spot casts a shadow onto
Hello Jim,
William Walton's Pinholes and Shadow Sharpeners and Gianni
Ferrari's The Shadow Sharpener, each in Compendium 9-4, December
2002, deal with this question.
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.
