Post by USM on Nov 24, 2006 14:05:23 GMT 8
How to get the light trails looking like they are following behind the moving object? You need to fire the flash right before the shutter closes. This is called 2nd curtain sync flash since the flash is fired about 1.5 ms before the 2nd curtain of the shutter starts to close.
However, using the 2nd curtain sync has its own demerit too.
Firstly, it is harder to take a photo in long exposure. With 1st curtain sync you can see the moving object in the viewfinder and can thus able to trigger the shutter at the exact moment. But with second curtain sync you can’t see the moving object when the shutter is open, because with SLRs the mirror flips up out of the way; and you have to predict accurately whether or not the object will still be in the frame at the end of the exposure period.
The E-TTL preflash occurs prior to the shutter opening, and so the flash will visibly fire twice when you’re using long shutter speeds and second-curtain.
This delay between preflash and subject-illuminating flash usually doesn’t have any negative side effects, but there are two cases in which it might be a problem.
First, if the subject is moving, then the preflash metering won’t be right for the final exposure - FEL may be required.
Secondly, the preflash might confuse human subjects if they’re expecting just one flash. They might assume you’ve taken the photo and walk off or look away from the camera.
However, using the 2nd curtain sync has its own demerit too.
Firstly, it is harder to take a photo in long exposure. With 1st curtain sync you can see the moving object in the viewfinder and can thus able to trigger the shutter at the exact moment. But with second curtain sync you can’t see the moving object when the shutter is open, because with SLRs the mirror flips up out of the way; and you have to predict accurately whether or not the object will still be in the frame at the end of the exposure period.
The E-TTL preflash occurs prior to the shutter opening, and so the flash will visibly fire twice when you’re using long shutter speeds and second-curtain.
This delay between preflash and subject-illuminating flash usually doesn’t have any negative side effects, but there are two cases in which it might be a problem.
First, if the subject is moving, then the preflash metering won’t be right for the final exposure - FEL may be required.
Secondly, the preflash might confuse human subjects if they’re expecting just one flash. They might assume you’ve taken the photo and walk off or look away from the camera.