20D and Strobe Firing

I recently purchased a set of alien bees strobes.

Its an all wireless radio setup with hotshoe transmitter.

At shutter speeds faster than 1/250 something is wrong. Like its flashing while my shutter is still opening. Half or portions of the photo are black (very dark) when this happens.

Can anyone help me out with this, is there a way to sync them up?

Thanks
Dan

X-Sync (maximum flash synchronization) speed on the 20D is 1/250. If you go faster than that, the sensor is not completely exposed when the flash is set off.

Actually, with studio flash systems the X-Sync is usually rated slower because those systems tend to be a bit sluggish. On the 20D, it's 1/125. See the middle of page 98 of the 20D manual.

What are you doing that you need faster than 1/125? For most applications, that's fast enough to let you control the ambient light.

Doug Pardee wrote in post #4170352
What are you doing that you need faster than 1/125? For most applications, that's fast enough to let you control the ambient light.

Well my exposures were too bright... I ended up turning the strobe power down. Was just curious if there was a better way.

I'm brand new to strobes.

The shutter speed has nothing to do with your flash exposure. It only controls the exposure from ambient light. If your flash exposure is too high, you need to turn down the flash by using Flash Exposure Compensation or whatever.

You might find this article to be helpful. It was written for the Digital Rebel series, but the 20D behaves pretty much the same as the XT/350D and XTi/400D. About the only differences of note are that the X-Sync on the 20D is 1/250 instead of 1/200, and the references to Custom Function 8 become Custom Function 14 on the 20D.

Great, thanks for the info!