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Canon REBEL TI Flash Sync Speed Question
"Dr. Slick" wrote in message om... Hi, I ended up getting the Rebel TI kit obviously. But i was wondering about using the built-in flash. In the "P" mode, you can see how the shutter speed is always set to the sync speed, which is 1/90 for the Rebel TI. However, the aperture always stays the same, because it is automatically set by the TTL exposure program, or something like that. In the "Tv" or "Av" modes, whether or not the flash is popped out or not, the exposure reading (flashing numbers mean under or over exposure) never seems to change. The only thing which will certainly happen when you pop the flash up, is that the shutter speed will be set to 1/90 if it was anything faster... If the shutter speed is slower than 1/90, then the EXPOSURE SETTINGS STAY THE SAME IN "Tv" or "Av". Why is this? I understand why the shutter speed must be 1/90 or slower, but why doesn't the "Tv" mode, for example, select a smaller aperture automatically when i pop up the flash? To compensate for the extra light from the flash? Probably because with today's electronics, the light from the flash can be extinguished to automatically limit the amount the film or sensing plane gets. The camera knows you want to use a given aperture (probably for depth of field reasons) so it chooses to quench the flash sooner to limit the light, rather then closing down the aperture. |
#2
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Canon REBEL TI Flash Sync Speed Question
"Dr. Slick" wrote in message om... Hi, I ended up getting the Rebel TI kit obviously. But i was wondering about using the built-in flash. In the "P" mode, you can see how the shutter speed is always set to the sync speed, which is 1/90 for the Rebel TI. However, the aperture always stays the same, because it is automatically set by the TTL exposure program, or something like that. In the "Tv" or "Av" modes, whether or not the flash is popped out or not, the exposure reading (flashing numbers mean under or over exposure) never seems to change. The only thing which will certainly happen when you pop the flash up, is that the shutter speed will be set to 1/90 if it was anything faster... If the shutter speed is slower than 1/90, then the EXPOSURE SETTINGS STAY THE SAME IN "Tv" or "Av". Why is this? I understand why the shutter speed must be 1/90 or slower, but why doesn't the "Tv" mode, for example, select a smaller aperture automatically when i pop up the flash? To compensate for the extra light from the flash? Probably because with today's electronics, the light from the flash can be extinguished to automatically limit the amount the film or sensing plane gets. The camera knows you want to use a given aperture (probably for depth of field reasons) so it chooses to quench the flash sooner to limit the light, rather then closing down the aperture. |
#3
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Canon REBEL TI Flash Sync Speed Question
"William Graham" wrote in message news:%weOc.177563$a24.147642@attbi_s03...
In the "Tv" or "Av" modes, whether or not the flash is popped out or not, the exposure reading (flashing numbers mean under or over exposure) never seems to change. The only thing which will certainly happen when you pop the flash up, is that the shutter speed will be set to 1/90 if it was anything faster... If the shutter speed is slower than 1/90, then the EXPOSURE SETTINGS STAY THE SAME IN "Tv" or "Av". Why is this? I understand why the shutter speed must be 1/90 or slower, but why doesn't the "Tv" mode, for example, select a smaller aperture automatically when i pop up the flash? To compensate for the extra light from the flash? Probably because with today's electronics, the light from the flash can be extinguished to automatically limit the amount the film or sensing plane gets. The camera knows you want to use a given aperture (probably for depth of field reasons) so it chooses to quench the flash sooner to limit the light, rather then closing down the aperture. Well, to put it in another way, in the "Tv" and Av" modes, the exposure settings DON'T CHANGE when you turn on/pop-up the flash. My digital Powershot G3, on the other hand, will show a faster shutter speed when i add the flash (in the Av mode), as I would suspect it should do, as there will be more light obviously. Maybe the Rebel TI is also doing this, except it doesn't show it in the chosen exposure settings? Slick |
#4
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Canon REBEL TI Flash Sync Speed Question
"William Graham" wrote in message news:%weOc.177563$a24.147642@attbi_s03...
In the "Tv" or "Av" modes, whether or not the flash is popped out or not, the exposure reading (flashing numbers mean under or over exposure) never seems to change. The only thing which will certainly happen when you pop the flash up, is that the shutter speed will be set to 1/90 if it was anything faster... If the shutter speed is slower than 1/90, then the EXPOSURE SETTINGS STAY THE SAME IN "Tv" or "Av". Why is this? I understand why the shutter speed must be 1/90 or slower, but why doesn't the "Tv" mode, for example, select a smaller aperture automatically when i pop up the flash? To compensate for the extra light from the flash? Probably because with today's electronics, the light from the flash can be extinguished to automatically limit the amount the film or sensing plane gets. The camera knows you want to use a given aperture (probably for depth of field reasons) so it chooses to quench the flash sooner to limit the light, rather then closing down the aperture. Well, to put it in another way, in the "Tv" and Av" modes, the exposure settings DON'T CHANGE when you turn on/pop-up the flash. My digital Powershot G3, on the other hand, will show a faster shutter speed when i add the flash (in the Av mode), as I would suspect it should do, as there will be more light obviously. Maybe the Rebel TI is also doing this, except it doesn't show it in the chosen exposure settings? Slick |
#5
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Canon REBEL TI Flash Sync Speed Question
Hi,
I ended up getting the Rebel TI kit obviously. But i was wondering about using the built-in flash. In the "P" mode, you can see how the shutter speed is always set to the sync speed, which is 1/90 for the Rebel TI. However, the aperture always stays the same, because it is automatically set by the TTL exposure program, or something like that. In the "Tv" or "Av" modes, whether or not the flash is popped out or not, the exposure reading (flashing numbers mean under or over exposure) never seems to change. The only thing which will certainly happen when you pop the flash up, is that the shutter speed will be set to 1/90 if it was anything faster... If the shutter speed is slower than 1/90, then the EXPOSURE SETTINGS STAY THE SAME IN "Tv" or "Av". Why is this? I understand why the shutter speed must be 1/90 or slower, but why doesn't the "Tv" mode, for example, select a smaller aperture automatically when i pop up the flash? To compensate for the extra light from the flash? I'm pretty certain there is nothing wrong with my camera, but i just wanted to be sure. Any information greatly appreciated in advance. Slick |
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