I tried to use second curtain sync flash on my 70D for the first time yesterday. I noticed, that it seems to fire too early. I'm using 1/10 s shutter speed with a moving light source in the image (to test this some more I just moved the camera with a static light source).
When I'm using first curtain sync, I get an image with the light trail starting directly at the position where the light source was at the time of the flash. When I'm using second curtain sync, the position of the light source at the time of the flash is at about 90% of the total trail length. This means that the flash happens about 10ms (10% of 1/10 s=100ms) before the shutter closes and makes the image look strange. This happens with both my 600EX-RTs as well as my 430EXIII-RT and also with the internal flash of my 70D.
Is this expected, or is there something wrong with my camera?
When I'm using first curtain sync, I get an image with the light trail starting directly at the position where the light source was at the time of the flash. When I'm using second curtain sync, the position of the light source at the time of the flash is at about 90% of the total trail length. This means that the flash happens about 10ms (10% of 1/10 s=100ms) before the shutter closes and makes the image look strange. This happens with both my 600EX-RTs as well as my 430EXIII-RT and also with the internal flash of my 70D.
Is this expected, or is there something wrong with my camera?