 Sepehr |
Canon A2 w/ 430ez metering problem Alright, I have a canon a2 w/a 430ez flash. the problem is that when I put everything in manual in a dim lit situation w/o the flash it'll be like 4" at f/3.5. but when I turn on the flash nothing changes, the camera's meter reads everything the same regardless of the fact that the flash is on. another scenario is when I put it on auto mode in a dim lit situation it'll set it at,for example, 1/60 at f/4 w/ the flash on. so I dont move the camera I just switch it too manual and put it to the settings the auto exposure did but now the camera reads that its underexposed and I changed the flashes power from 1/1, all the way down to 1/32 w/o any change in meter reading. help would be appreciated very much. and sorry if this was long and confusing.
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Jon Close |
See http://photonotes.org/articles/eos-flash/ for a terrific explanation of flash photography with EOS cameras. The light from the flash dissipates very quickly with distance, so there are effectively two zones of exposure: The flash-lit near subject, and the ambient-light background. The flash exposure is regulated by the lens aperture and the output set by the TTL metering system. Shutter speed is irrelevant. The flash duration is only 1/500-1/10,000 second, so the film collects all the flash output whether the sutter speed is 1/200 or 30 seconds. The backgound exposure is regulated by shutter speed and aperture. The light from the flash adds little to no light at distances beyond the subject. In P, green box, and icon modes, the camera defaults to a "snapshot" flash mode. It sets a high shutter speed (1/60 to 1/200) so there is no blur from handheld camera shake, and adjusts the aperture as much as it can to expose the background. The meter reads "0" in these simplified modes because it will give proper exposure to the flash-lit near subject. In Av, Tv, and M modes, the meter gives the ambient light exposure. In these modes you are able to directly control the balance of flash and ambient exposure. You can set them for equal exposure ("0"), set the background for 1 stop less exposure than the flash ("-1") to let the subject subtly stand out, or any other combination.
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Sepehr |
thanks for responding so quickly, I think I might have gotten a grasp on it. my other question is that I have an optical slave and a flash so I was wondering what exposure differences hsould be made? and because I am planning on usong more than 1 flash I think I should maybe invest in a hand held light meter. thank you.
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Kerry L. Walker |
A flash meter would be a good idea if you plan to use additional flash.
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