The lights most friendly to the night sky and to your neighbors are "Full Cutoff" lights. Plain "Cutoff" lights are better than most lights, but they still let light shine upward and into others' eyes. Some local ordinances require "Fully shielded lights, which allow no uplight but may not have the glare zone control that Full cutoff lights have. If you are above the a fixture, and can see either thelamp or the lens, they aren't even fully shielded, let alone Full Cutoff.
Any non-cutoff fixture will light things and eyeballs that don't need light. Cutoff fixtures allow some up-light and glare. They can usually be spotted by the lens (drop lens) or other glass that is visible below the fixture.
CUTOFF
CLASS
ILLUSTRATION
Full cutoff fixtures have flat lenses or no lenses that throw light sideways. No direct light or glare is visible at a distance
Seeing a light bulb gives people a feeling of having useful light. The two are not the same. Light itself, light on the ground and on objects that need to be seen is needed. The light itself must be directed down on the lighting targets. In fact, seeing the bulb itself interferes with seeing what a person needs to see.
Driggs' old overhead Main Street "cobra" streetlights are drop lens style and can be seen for miles. The newer overhead lights at Driggs traffic light are full cutoff and don't glare in peoples eyes except under the fixture where the lights are supposed to shine, and they aren't visible out into the country as the old ones are. Driggs new lights on Little Street are some of the best of the "Acorn" style, but they put 9% of their light directly upward. The are fitted with shields that cut off some of the light into people's houses. The are visible for a long distance.
Victor's Main Street lights are designed to be full cutoff, if they were fitted with clear glass sides. Their frosted glass cuts some glare but diffuses some light up into the sky. Newly installed lights in Victor are fully shielded and of good design.
GOOD FIXTURE TYPES SKETCH
The lights in the Victor Ward Church parking lot are a good example of full cutoff lights. They are about 20 feet high, so they aren't visible very far into the sidewalk or street. They light the lot but don't shine in drivers' eyes. Notice them when you go by there. The are bright enough because they light the lot well.
The lights in the Creekside Development are good lights that do not glare in drivers' or pedestrians' eyes.
Good residential fixtures are just now coming available. A regularly updated list of good fixtures is at the International Dark Sky website Good lighting Fixtures and Where to Get Them.
