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08/19/2006 08:43:11 PM · #1 |
While taking outdoor portraits using the 550EX for fill flash, I cannot use any speed faster than 1/200. I have the camera set to manual, but it won't change the speed to any faster than that with the flash on. However, unless I change the aperture, that speed is often too overexposed with the fill flash.
Any idea why this is happening? I ended up taking a lot of photos without the flash when I think it would have helped. |
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08/19/2006 08:45:56 PM · #2 |
Because 1/200 is the fastest sync speed for the camera.
If you need to use a faster speed, you have to turn on the High Speed Sync option on the flash.
In the camera menu, you also have to make sure the sync speed is not set to default to 1/200
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08/19/2006 08:46:46 PM · #3 |
Might be the same with the 10D, but with the 300D 1/200 is the fastest that the camera is programmed in to allow. It's pretty annoying! No idea why its like that... maybe someone can shed some light?
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08/19/2006 08:49:23 PM · #4 |
I believe that is because the flash sync speed maxes out at 1/200th for your model. Basically that is the fastest speed exposure at which the image sensor is exposed all at once. In order to obtain faster shutter speeds, the shutter actually sweeps a bar of light over the image sensor, the faster the shutter speed, the thinner the bar of light.
It's basically like a moving window passing over the image sensor at speeds faster than 1/200th (some cameras are faster, like 1/250th. many medium format cameras can do 1/500th because the aperature blades in the lens also act as the shutter) so that if you took a flash shot during that time, it would only illuminate the part of the image sensor that the "window" was passing over at that exact moment. The duration of the flash itself is much shorter than a 200th of a second, but it is limited by the speed at which the shutter passes over the image sensor.
Help me out if I'm wrong here folks.
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08/19/2006 09:12:25 PM · #5 |
I believe you are correct. 1/200 is the highest speed at which the entire sensor is exposed to the light for the entire duration of the exposure. In in other words the fastest shutter speed at which the "window" formed by the shutters is full sized rather than some sort of "moving slit."
If you turn on High Speed Sync on the camera then the flash emits a strobe-like burst of flashes to ensure that it illuminates the subject for the whole time the "slit" is moving. Its quite effective but does chew up batteries pretty quickly.
Originally posted by Army of nOne:
I believe that is because the flash sync speed maxes out at 1/200th for your model. Basically that is the fastest speed exposure at which the image sensor is exposed all at once. In order to obtain faster shutter speeds, the shutter actually sweeps a bar of light over the image sensor, the faster the shutter speed, the thinner the bar of light.
It's basically like a moving window passing over the image sensor at speeds faster than 1/200th (some cameras are faster, like 1/250th. many medium format cameras can do 1/500th because the aperature blades in the lens also act as the shutter) so that if you took a flash shot during that time, it would only illuminate the part of the image sensor that the "window" was passing over at that exact moment. The duration of the flash itself is much shorter than a 200th of a second, but it is limited by the speed at which the shutter passes over the image sensor.
Help me out if I'm wrong here folks. |
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08/19/2006 09:29:36 PM · #6 |
Okay...I'm glad I wasn't just being stupid and doing something wrong. :) Now I just need to learn more about how to set the high speed sync.
Thanks very much for the info! |
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