 BetterPhoto Member |
how to caliber light /flash meter minolta iv i am having flash meter minolta iv, I want to have correct caliberating . so as to get perfect reading on daylight or while using with studio lights. guide me in this reagrd
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Alan N. Marcus |
Reading your posting, I interpret the question to read— I have a Minolta light meter. Is their test I can perform to check the accuracy of this instrument? Hi Dipak M, Caliberating a meter is very difficult for you on anyone. If you must test! Purchase a photographic Gray Card. You can buy them on line from various sources These placards are cardboard, medium gray in color with a surface that reflects 18% of the ambient light thus they absorb 82% of the ambient light. Load a film camera with fresh moderate speed black & white film. Take a close-up reflected light reading of the card under daylight conditions in open shade. Expose the film exactly as the meter recommends. Make a series of close-up exposures of the gray card .You are making a test sequence centered on the recommended reading each exposure incremented from the next by a full f/stop change. Adjustment to exposure is made using only the camera’s aperture control. You repeat making a test sequence in the studio using electronic flash as the light source. When testing electronic flash allow extra time between exposures to insure the flash unit’s capacitors are fully recharged. Develop the film carefully. Use fresh chemicals mixed accurately. Develop at the recommended temperature (generally 68°F -- 20°C). Time the developing process exactly per instructions on the developer label. Agitate continually for the first 30 seconds, then for 5 seconds at 30 second intervals until developing time is complete. Use fresh stop-bath and fixer. Wash 30 minutes with running water. When the film is dry, take to a local one-hour shop. Ask the shop to read the clear film and the exposures of the gray card on their densitometer using the yellow filter setting. The correct reading for the image of the gray card is 0.75 plus clear film reading i.e. 0.75 plus base fog. Expect an error of ±..10 the generally excepted norm which takes all factors into account. One f/stop error = ± .30 Alan Marcus (techno babble par excellance
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