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Karen Thomas |
Meter Readings Through the Lens I have asked this question before with no response, so I'm going to try again. I have a Canon Rebel 2000 camera and love it! But I'm confused as to the meter readings I get through the lens of this camera. With the flash ready to use, I put the command dial on P (which stands for program) and press the shutter button half down while composing my subject to get a meter reading. Then if I put the command dial to M (which is the manuel setting) and program the same aperture setting and shutter speed, still with the flash ready to fire the meter reading says it's way under exposed (-2). Both instances are done with the same subject, lighting, and distance. Does the meter not read correctly when the flash is activated? I've taken the camera back to where I bought it and had the owner check it out and he says the camera is ok. When the flash is not activated the meter shows both settings (the P and the M settings) are in good exposure. This only happens when the flash is activated, ready to be used. I love this website; thanks for all your professional answers! - Karen
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Jon Close |
I have done this with my Elan IIe (copied the Program exposure settings over to Manual), but not in flash mode. I find that the camera's computer can manipulate flash guide numbers much more quickly and accurately than I can, so I almost always do flash photography in P, Av, or Tv modes rather than Manual. Have you tried shooting the same scene in both the Program and "underexposed" Manual modes? Did the Manual shot actually turn out underexposed (darker negative, don't compare the prints) than the Program shot, or were they virtually the same? I know that the metering mode for the Rebel 2000 changes when you switch from Program to Manual. In Program mode it uses A-TTL (Canon's "Advanced" Through The Lens) 3-point/4-zone metering with the built-in flash. In Manual mode it uses the simpler TTL and single-zone center-weighted metering. My guess is that the A-TTL recognizes a main subject within the range of the built-in flash, and calculates shutter and aperture to properly expose that area and let the rest of the scene be darker. In Manual the center-weighted metering is averaging virtually the entire scene and calculates the built-in flash is not powerful enough to light it all at the selected shutter and aperture settings. In non-flash mode the Program (35-zone Evaluative) and Manual (Centerweighted) both average the entire scene and so their exposure calculations will be much closer (at least for simple, evenly lit situations).
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Jon Close |
I'd like to change my answer, Regis ;) Playing with my Elan IIe and checking my manual this evening I've figured out the right answer. While I was right that switching the Rebel 2000 to Manual mode changes the metering from Evaluative to Centerweighted, that is not the reason the Program's shutter and aperture settings read "underexposed" when applied in Manual mode. In Program mode with the flash active, the camera balances the ambient light and flash. When it's bright, the shutter speed (limited to the flash sync speed) and aperture are set to properly expose the background, and the flash is limited (through A-TTL/TTL) to emit just enough light to provide fill-in. When it's dark (indoors or at night), the Program mode won't set a shutter speed slower than can be handheld (between 1/15 and 1/90) and the flash will fire at higher or full output and be the main light source. The exposure scale reads "0" because it's counting on the flash to provide enough light. Using the flash in Manual mode works the same way it does for Aperture priority (Av) and Shutter priority (Tv). In these modes, the metering is entirely for the background or ambient exposure without regard for the flash. The camera will meter the scene the same way whether the flash is active or not, except that with the flash the maximum shutter speed you can set is the flash sync speed (1/90 for the Rebel 2000). For example, in a dim or night situation the Program mode may set 1/60 and f/4. When you take the picture the flash provides enough light to properly expose your subject, say a person 8 feet from the camera, but the background beyond that person will be dark or under exposed. In the same situation in Manual mode if you set 1/60 and f/4 you'll get the same result (though the scale will read "-2" or more). If however you set it to say 1 sec. and f/4 to get the meter to "0", then the flash will provide just enough light to properly expose that person 8 feet away, but the shutter will remain open long enough to properly expose the background, too. Hope this helps.
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