----- Original Message ----- From: "Mac Oglesby" <[EMAIL PROTECTED]> To: "SUNDIAL" <[email protected]> Sent: Friday, October 14, 2005 3:40 AM Subject: Images
> > Hello, > > Apropos of our ongoing discussions about shadow-sharpeners and > pinhole images, take a peek at today's (14 October 2005) Astronomy > Picture of the Day. > > http://antwrp.gsfc.nasa.gov/apod/astropix.html > > Or, http://antwrp.gsfc.nasa.gov/apod/image/0510/eclipseshirt_haake_f.jpg > > Best wishes, > > Mac Oglesby > - Hi All: For those interested in this subject, here is a chart that I developed for pinhole shadow sharpners. It shows the relationship of pinhole diameter to the focal plane between 5 and 15 inches. There is also a brief explanation of the process used to arrive at the results given. The relationship, while not perfectly linear, should give a good starting point for distances outside of the ranges included in the chart. http://www.atensundials.com/pinhole.html Here is another site with an interesting experiment in pinhole astornomy, a bit OT but some good information. http://users.erols.com/njastro/barry/pages/pinhole.htm Happy dialing Dave G. Http://atensundials.com -
