Synchronization problems with Rekam NEO 200 and Canon 600D

Question

I've recently got two Rekam NEO 200 lamps with synchronization cable. To connect them to my canon 600D i've bougth an adapter.

The flash seems to sync correctly when setting exposition to values 1/320 and higher. The problem appears when i try to set exposition to 1/500 or less. With the value of 1/500 i get half of the photo black, and setting exposition to 1/1250 make the whole photo black. I'm not an expert in photography so I'm interested if it is possible to make the flash synchronize in appropriate way when exposition it set to a low value such as 1/500 or even lower?

Answer 1

That is not a synchronisation problem, that's a limitation of a focal plane shutter, at speeds faster than 1/250s the shutter starts to close before it is fully open, therefore when the flash fires the shutter is not fully open and part of the image wont be lit by the flash, showing up black.

There is very little you can do about this, some flashes are able to pulse very quickly, effectively acting as continuous lightsources, but vastly reducing power output in the process.

Why do you need to use faster shutter speeds? If it is to freeze a moving subject then there is no need as the short flash duration does that for you, up to a point. For this to work the flash must be significantly brighter than the ambient light.