@Bryston3bsst wrote:Am I missing something here? The manufacturer doesn't "set" the maximum sync speed. It's an inevitable consequence of the maximum speed at which the shutter curtains are able to travel. You can say that Canon should have used a faster shutter on the 6D, but their response would probably be that doing so would have increased the price of the camera.
A focal plane shutter achieves its high speeds by having the second curtain start to close before the first curtain has finished opening. So for all the speeds above a certain value, what the sensor sees is a slit travelling across its surface. The higher the shutter speed, the narrower the slit. So for those speeds, there's no time at which the flash can fire and light all of what the sensor sees. The maximum sync speed is the maximum speed at which the second curtain doesn't start to close until after the flash has had time to fire with the first curtain fully open. On the 6D that speed is, I believe, 1/180 sec
Some high-end external flash units are able to fire a series of flashes in rapid succession while the slit travels across the sensor, thereby allowing flash to be used with some degree of efficacy at speeds above the maximum sync speed. But that's not what was being referred to in this thread.
My first film Nikon had, IIRC, a maximum sync speed of 1/30 sec. So obviously a lot of progress has been made, and I find it a bit hard to feel sorry for those complaining about the sync speed of the 6D. 
And the probable reason that your 600D had a higher sync speed than the 6D is that it was a crop frame camera, so the shutter curtains didn't have as far to travel.
