...I'm using a formula that Ralph Lambrecht posted on a pinhole thread here, which is PinholeDiameter=sqrt( (2.44)(wavelength)(Focal Length) )
I found on a seperate website (cant remember where) that 5500Angstroms is the wavelength of average daylight, so I guess I'll go with that. That same website said 1Angstrom = 1nm, which is 0.00055mm, right?
To convert 7.5inches to millimeters, I multiplied 7.5 by 2.54 to get 19.05cm. I multiplied that by 10 to get 190.5mm.
i plugged the wavelength and focal length in millimeters in to the formula. Assuming I did my math right, the diameter should be about 0.5mm. Is that right?...