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A photograph showing two Fulton MX-991/U Flashlights, next to an unofficial reproduction and a standard angle-head flashlight. The MX-991/U Flashlight (aka GI Flashlight, Army flashlight, or Moonbeam [1]) from the TL-122 military flashlight series of 1937-1944 and is a development of the MX-99/U flashlight issued in 1963 [clarification needed].
Cameras with focal-plane shutters—even if they had PC connectors with X, F, M, or S-sync delays ("xenon sync" with zero delay and flashbulbs with peak delays of 5, 20, and 30 ms)—could not be used at speeds that attenuated guide numbers with most types of flashbulbs because their light curves were characterized by rapid rise and fall rates; the second shutter curtain would begin wiping ...
Didymium glasses. Didymium (Greek: δίδυμο, twin) is a mixture of the elements praseodymium and neodymium.It is used in safety glasses for glassblowing and blacksmithing and filter lenses for flame testing, especially with a gas ()-powered forge, where it provides a filter that selectively blocks the yellowish light at 589 nm emitted by the hot sodium in the glass without having a ...
A kit lens is a "starter" lens which can be sold with an interchangeable-lens camera such as a mirrorless camera or DSLR. It is generally an inexpensive lens priced at the lowest end of the manufacturer's range so as to not add much to a camera kit's price.
There are many "do it yourself" headlight restoration kits available for purchase. A few of the major brands that produce these kits include 3M, Turtle Wax, Sylvania, Rain-X,and Rust-Oleum. Most of these kits require multiple stages of wet sanding to remove the oxidation of the headlight lens, usually with descending level of grit (coarse to fine).
This means the lens's F-number value is fixed to the overall designed focal ratio of the optical system (the diameter of the primary mirror divided into the focal length). The inability to stop down the lens results in the catadioptric lens having a short depth of field.
Rodenstock lenses for large-format cameras; L–R: Grandagon-N 115 mm f /6.8, Apo-Sironar-S 210 mm f /5.6, Grandagon-N 90 mm f /4.5 Rodenstock Photo Optics traces its origins to a mechanical workshop founded in 1877 by Josef Rodenstock and his brother Michael in Würzburg, Germany.
If a lamp has a 1 lumen bulb and the optics of the lamp are set up to focus the light evenly into a 1 steradian beam, then the beam would have a luminous intensity of 1 candela. If the optics were changed to concentrate the beam into 1/2 steradian then the source would have a luminous intensity of 2 candela.