 BetterPhoto Member |
Flash Problems - Underexposure Why do my pics come out under exposed when I use flash?
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Ken Pang |
All flashes should have a power rating called a Guide Number, or GN. This is an indication of how far the flash should reach. If you are using a compact camera, usually the range is about 2 to 3 meters or so. Even most flashes inbuilt to a SLR doesn't go much further. Anyway, once you have the GN, find out the aperture of the lens, and divide. So, for example, on the EOS 5, the GN is 13, and my lens is a 3.5. So the flash would reach 13/3.5 or 3.7 Meters on ISO 100 speed film. This increases as your film speed increases (forgot the formula for that, can someone help me out?) Also, to calculate the minimum distance, divide that number by 5. Any closer than that, and everything will just be washed out. So, in my case, anything less than 70cm or so will be washed out. Hope this helps.
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Jorge Felix |
We need to know what camera and flash you are using. And what are you shooting? It seem's that you are trying to shoot from a distance too long or the aperture in the lens does not match the flash guide number. Regards,
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