What caused rhis to my photos

[KmH]

Your shutter speed was father then the flash. Check what the max sync speed is on your flash.

Actually the shutter was slower than the flash. An on camera flash unit at full power fires in about 1/1000 of a second.
At less than full power the duration of the flash is even shorter, exceeding 1/10,000 of a second.

The lens projects the image on the image sensor upside down.
So the bottom of the image is actually at the top of the image sensor.
DSLR shutter curtains move fron the top of the camera to the bottom so gravity aids their movement to control an exposure.
The black bar is caused by the second/rear shutter curtain blocking part of the image sensor as it was closing to end the exposure.
We can also tell that the flash was sync'd to fire as soon as the first/front curtain was fully open.

At 1/350 one or the other of the shutter curtains will always be covering part of the image sensor.
1/200 is the fasted shutter speed that has both shutter curtains fully open, and is also known as the maximumx-sync shutter speed.

 

[pgriz]

The phenomenon happens because the shutter is actually made up of two curtains. The first curtain opens, light comes in. The second curtain closes, light entry stops. This works up to a certain speed usually termed the maximum sync speed. With shutter speeds above this, the second curtain starts to close before the first curtain is completely open, in effect creating a travelling slit. So if you when you trigger your flash with speeds higher than the sync speed, the area in front of the sensor is never completely open, and the flash image will be partly blacked out (the blacked out portion is the shadow of the shutter curtain still moving across the face of the sensor when the flash goes off). Depending on the exact moment the camera tells the flash to fire, you may have the dark band at the top, at the bottom, or both.

Camera manufacturers overcame this sync speed limitation by building into their flashes an ability to fire multiple times in very rapid succession. This allows the use of higher shutter speeds (the ones where you have a travelling slit of different widths) because the flash actually fires multiple times while the slit is in motion, in effect building up multiple flash exposures on the sensor. While this is a neat trick, this also reduces the amount of power (which translates to amount of light) the flash can put into each individual flash, so when using "high-speed" flash (as this feature is called), the range of the flash is reduced.

With respect to flash exposure - the camera's meter does not have the ability to meter flash exposure independent of the ambient light exposure. For that purpose, photographers use a flash meter which DOES measure both flash and ambient, and allows a photographer to know what settings to use. Flash exposures are actually two exposures in one - the ambient light has a contribution (determined by aperture and shutter speed), and the flash has a contribution determined by the flash power setting, and the aperture. So aperture becomes the common factor when shooting a combined aperture/flash exposure.

If you are using direct flash, you can usually figure out the flash-subject distance for a given aperture using the guide number (guide number divided by aperture gives you the distance the flash should be from the subject). However direct flash is too harsh for the majority of flash applications, and therefore the practice is to bounce or diffuse it. Now the formula has no idea of how much of the flash's light actually ends up on the subject, so either you use trial and error, or you use a flash meter.

edit: didn't notice Keith's post (sorry Keith :blushing - we're talking about the same thing as far as sync speed is concerned.