Half image black

I recently experienced a weird problem and it popped up again today so I'd like to hear if anybody else has experienced this and what might be causing it.

When using a radio trigger and my two studio lights I sometimes get one side of the image that is totally black when shooting in portrait mode, it's as if the image has been cut down the centre (vertically) and one side is black and the other side is normal exposure.

Today I found that when shooting in landscape mode I had the bottom half of the image totally black with the top half perfectly exposed. If i reduce it by 1 stop it's back to normal. Is this somehow connected to the shutter being only half open when the shot is taken? I never had this with my 350D so is it a problem with my 40D?

Looking forward to hearing your thoughts
Cyrus

Your shutter speed has passed the Camera's Sync speed of 1/200 or 1/250 .

some are higher, but on yorus its 250 i believe

unless you have high speed sync activated on ETTL you cannot go above 250/200

Cyrus wrote in post #7739191
Is this somehow connected to the shutter being only half open when the shot is taken?

Yes. http://pixsylated.com …hs-about-high-speed-sync/

thanks heaps for your prompt replies people. I should have worked that out but I've been too busy lately to actually sit down and work through from the basics. You have saved me pulling my hair out but I'm glad that I as on the right track with the shutter speed.

Thanks again
Cyrus

"A man's got to know his limitations"...

Dirty Harry -- Magnum Force

Syncing with strobes often means that you are working below your cameras max sync speed. My 5D has a sync speed of 1/200; however, I need to shoot at 1/160 when I'm using studio strobes.

You said you were using a radio trigger. When the battery starts running low in either the sender or receiver, the processing of the signal lags and sets the flash off late. You then get a shutter shadow even at proper sync speeds. Some radio triggers under the best of circumstances won't allow you to use the shortest shutter speed that would ordinarily sync with flash. For instance, if your maximum sync speed was 1/250, you may only be able to use 1/200 or even 1/160. Do a few test shots with your radio triggers, and if you are much below the maximum sync speed, replace the batteries. I would replace the receiver first since my experience is that they will drain batteries much faster than the sending unit. With my "poverty wizards" I always remove the batteries from the receiver when I store it between shoots because it will run them down even when idle.