I Need Some 600EX Help

MDJAK wrote in post #16416577
I once asked the question why the AF assist beam can't work in AIServo, and someone answered that the red pattern projected on the subject would then show up in the picture.

It would only have to turn off for the time the shutter was open. I assume there is some other reason. I mean, if the shutter were open the same amount of time as the light were off, wouldnt the image be both in focus and without the beam?

JakAHearts wrote in post #16416593
It would only have to turn off for the time the shutter was open. I assume there is some other reason. I mean, if the shutter were open the same amount of time as the light were off, wouldnt the image be both in focus and without the beam?

Yes, it would have to go off as the mirror lifts and the shutter opens, then back on again after the shutter closes. I'm not sure if this on and off flashing of the light would cause focusing problems during continuous focusing or not. Presumably not if the shutter speed is fast enough.

rrblint wrote in post #16417647
Yes, it would have to go off as the mirror lifts and the shutter opens, then back on again after the shutter closes. I'm not sure if this on and off flashing of the light would cause focusing problems during continuous focusing or not. Presumably not if the shutter speed is fast enough.

I don't think so because if that were the case, just lifting the mirror would cause the af system to stop. I think the af guesses were the subject will be when the mirror moves out of the way and the sensor is exposed.