12-22-2010, 04:10 PM
quote:
Originally posted by Royall
David.... What's a flash bulb??? Not a whole lot of rain down on Maku'u. Seen one flash but it's been pretty quiet.
Royall
Because you asked.... from Wikipedia
The earliest flashes had of a quantity of thermite flash powder that was ignited by hand. Later, magnesium filaments were contained in flash bulbs, and electrically ignited by a contact in the camera shutter; such a bulb could only be used once, and was too hot to handle immediately after use, but the confinement of what would otherwise have amounted to a small explosion was an important advance. An innovation was coating flashbulbs with a blue plastic coating to match the spectral quality to daylight balanced colour film and to make it look more moderate, as well as providing shielding for the bulb in the unlikely event of it shattering during the flash. Later bulbs substituted zirconium for the magnesium, which produced a brighter flash and tended to temporarily blind people.
Flashbulbs took longer to reach full brightness and burned for longer than electronic flashes. Slower shutter speeds (typically from 1/10 to 1/50 of a second) were used on cameras to ensure proper synchronization. A widely used flashbulb through the 1960s was the number 25. This is the large (approximately 1 inch (25 mm) in diameter) flashbulb often shown used by newspapermen in period movies, usually attached to a press camera or a twin-lens reflex camera.
David
Ninole Resident
Ninole Resident