I also have used the small low voltage halogen lights as "point" sources. Many filaments are only a few millimeters long. You can get higher outputs from those designed for spot lights or fog lights in auto parts stores in the U.S. These run on 12v and may require a high wattage transformer.
In simulating the sun, such a point source may need to be placed far enough away to get about 1/2 degree angle divergence. This may cause the brightness to fall off too much for some purposes. I overcame this with the placement of a cheap plastic Fresnel lens in front of the lamp ( placing the lamp at the focus of the magnifier in order to get near parallel light). This has the disadvantage of limiting the size of the beam. However, cheap Fresnel lenses of about 8 inches in diameter can be found as "page magnifiers" in stationary stores. They are designed to be placed on top a page of print. Claude Hartman 34 N 120 W "J. Tallman" wrote: > > Hello All, > > I am taking some documentary photographs of a new sundial concept and > I need a little help. > > I recall reading several postings in the past that referred to using a > point light source to simulate the sun. This would be very helpful in > simulating conditions such as solstice and equinox declination, as > well as any desired time of day. Accomplishing these various > conditions outdoors is proving very difficult (and hot!), so I would > like to set up an indoor photo shoot with a common backdrop. This way > I hope to create the ideal times and declinations for my instruction > sheets. > > Does anyone have any suggestions for a good point light source to > use? I have tried several flashlights and lightbulbs and I keep > getting fuzzy shadows. The best "point of light" I have found so far > is a mini MagLight flashlight with the reflector assembly > removed...but iX-Mozilla-Status: 0009I would like. Any ideas? > > Jim Tallman > Artisan Industrials -
