canon Xs shutter speed question

[C&EPhotography]

I am using a Canon Xs with a 50mm f1.8 lens shooting outdoor evening photography. I was using an external flash as fill light as the sun was behind my subject and noticed that the shutter speed would not exceed 1/200... Is it just syncing with my flash and will not allow a faster shutter speed or what? I want a shallow depth of field so im shooting f1.8, but since im using fill flash, my shots are way overexposed at 1/200...Im shooting in manual mode...any suggestions or is something set incorrectly that Im not seeing...

[autofocus]

It's the sync speed limitation of the camera when using the flash. Two options:
1) high speed sync if your camera and flash support it
2) an ND (neutral density) filter for your lens which will cut the ambient light and allow for a wider aperture

[SusanH1970]

You can also try shooting in aperture priority mode. The flash will automatically (in TTL mode) sense that you only want it to flash for fill.

Or so I've been told...never tried this on my own but I read it somewhere here on DPS, lol. And that's assuming you're using the same flash as me, a 580EXii.

[inkista]

The sync speed limitation is about the gap between the shutter curtains, and the fact that a flash burst is far faster than your maximum shutter speed.

The faster the shutter speed on the camera, the smaller the gap between the front and the rear curtains becomes. At 1/200s, the gap between the two curtains is large enough that your whole sensor can "see" the flash's burst when it goes off. But if you go faster than that, the gap gets smaller than your sensor, and the curtains will cover the top and/or bottom of the sensor when the flash burst goes off: result, you have dark bars at the top and/or bottom of the frame.

That's why your camera limits you to your max. sync speed when you're using a flash.

High speed sync is a feature where the camera body can tell the flash to send out multiple bursts, timed to the sweeping of the gap across the sensor so that the entire sensor receives an even amount of light from the flash, but this drastically reduces your flash's power output, and most typically requires an OEM flash and a hotshoe connection, an eTTL-capable sync cable, or very expensive radio triggers to work. If your triggering system only connects to the center pin on the flash/camera hotshoe, you can't use high-speed sync.

Further reading: http://neilvn.com/tangents/2010/08/0...ed-flash-sync/