Slow curtain or bad camera
 

Canon 60D
50mm f 1.4
28-75mm f 2.8
3 external flashes
I was using a white paper backdrop with an umbrella soft box and hair light experimenting on some photos ( I'll try to attach) But I have this bar that looks like a when the shutter is too fast for the flash. It's on the bottom. When I turn the camera it will be on the side. It shows on this camera when I set the shutter at 250. It doesn't do it outside or when the flash is on the camera. Doesn't matter what lens.
Wonder if anyone else has had this happen. Never happened before and the only thing I did different, now that I think about it was add the hair light behind.It's a little better with a higher ISO
For the pictures I shot spot meter

1/160 f 2.8 100 iso 48 mm 28/75
1/160 f 3.5 100 iso 50 mm f 1.4 usm
1/125 f 2.8 125 iso 75 mm f 28-75mm

I'm going to shoot some more but if anybody has any ideas I'd like to try them
Thanks!

Re: Slow curtain or bad camera
 

Bad shutter synch usually shows as a hard edged black area where the shutter covered the film/sensor. The edge on your examples have a soft edge so whatever was blocking the light was not right against the sensor. Almost looks like the mirror was dragging.

Re: Slow curtain or bad camera
 

Humm, a dragging mirror? Might explain why it doesn't matter what lens. No problems when the flash is attached or outside

Re: Slow curtain or bad camera
 

That would seem to rule out the mirror. Besides, I'd think there would be a sensor to determine an "up state" before firing the shutter. How about a matte box or flag?

Re: Slow curtain or bad camera
 

Don't have a matte box but I could make a flag. I didn't used to do this is the reason I thought something was going bad. I always shoot with the same set up (except for the snoot) because I'm new at it I stick with what works and change one thing at a time, odd it only seems to fault when the flash is off the camera but I have to test more. Thanks for the info
Art