Can't synch with studio lights two eos cameras via slaves

<p>Its been a long time since I used studio lights with film cameras. I'm trying with digtal and not getting good sync.</p>

<p>Both cameras on Manual Exp.<br>

Flash exposure set from by lightmeter reading (f16).<br>

No preflashes from camera.<br>

Slaves are being triggered by body's own flash.<br>

Tried 1st and 2nd curtain sync.<br>

Can always seem to see the flash fire through the viewfinder.</p>

<p>Here is typical role of flash im getting (dodged area is where flash is and yes this was a long shutter for flash of shutter of one second. That was 1st curtain sync.<br>

<a href="http://www.imagebam.com/image/37e32d125920437" target="_blank"><img src="http://thumbnails26.imagebam.com/12593/37e32d125920437.jpg" alt="imagebam.com" /></a></p>

<p>My next change was to 2nd shutter synch and although the marked strobe did not flash, a strobe on the other side of the light tent did. Again 1 second exposure. But when I began to turn down available light via shutter I again see no sync even at 1/60 which the 350D and 550D should do easily.<br>

<a href="http://www.imagebam.com/image/8a6ca8125920460" target="_blank"><img src="http://thumbnails35.imagebam.com/12593/8a6ca8125920460.jpg" alt="imagebam.com" /></a></p>

<p>Any idea what I'm missing to sync at a decent speed of 1/125?</p>

<p>"Both cameras on Manual Exp.<br />Flash exposure set from by lightmeter reading (f16).<br />No preflashes from camera.<br />Slaves are being triggered by body's own flash."<br>

============================================<br />huh ? I don't get it are you using 2 cameras ? The pre-flash comes form the flash not the camera, what do you mean by slaves are being triggered by body's own flash ? </p>

 

<p>[[No preflashes from camera. Slaves are being triggered by body's own flash.]]</p>

<p>You cannot disable the pre-flash from the on-board flash on the the 350D or the 550D.</p>

<p><em>huh ? I don't get it are you using 2 cameras ?</em><br />Tried 2 cameras to rule out a fault on the first I tried.<br /><em></em><br /><em>The pre-flash comes form the flash not the camera</em><br />Errm yes I know its the flash on the camera that flashes and not the body or lens if thats what you mean? :-\ ?<br /><em></em><br /><em>what do you mean by slaves are being triggered by body's own flash ?</em><br />The remote strobes have slaves that are triggered by the flash on the camera body.</p>

 

<p>Ok maybe I need to explain what I meean by <em>preflash. </em></p>

<p>I mean the flash from the camera is a single flash and sync-ed to the shutter, to make the exposure.</p>

<p>I make the point to avaoid going in to this: people sometimes using redye reduction or something that causes the camera to preflash the subject which would obviously set off the remote strobes before the shutter opened.</p>

<p>As Rob stated there is no way for you to disable the preflash on those two cameras. I believe you can do this on the 60D and 7D but I'm not certain. The preflashes happen so fast that you can not perceive them. There is a workaround though. Press the * button on the back of the camera, let your slaves recycle, take your shot.</p>

<p>Read your manual for Flash Exposure Lock. That's what you're doing when pressing the * button. You have 30 seconds to take your shot before FEL goes away and you're stuck with preflashes again.</p>

<blockquote>

<p>Can always seem to see the flash fire through the viewfinder.</p>

</blockquote>

<p>Since the slr camera's mirror flips up during exposure this is the giveaway the flashes aren't firing during exposure but likely just before.</p>

<p>Henry Posner<br /><strong>B&H Photo-Video</strong></p>

<p>Well thank you Dan. I did not have any idea there was an imperceptible pre flash as standard. I did get a hint because through the viewfinder I saw the remote strobes flash just before the shutter went up. I just argued this with a friend who would not believe what I saw, but an 'invisible' flash answers this.</p>

<p>I have tried your suggestion with the flash lock and eveything is back just like the good old simple film camera days!! </p>

<p>Thanks.</p>

<p>Thanks Harry missed your post. That is what I was seeing and surmising, but I could not find a reason (therefore resolution) as to why that was the case. Thanks to Dan now I do.</p>

<p>[[i did not have any idea there was an imperceptible pre flash as standard]]</p>

<p>It's the whole point behind the ETTL system.</p>

<p>http://photonotes.org/articles/eos-flash/#ettl</p>

<p> </p>

<p>ETTL? see vacant look on my face! :) I've only really used studio lights with a flashmeter and Sinar or Mamiya 642 and a few other cameras. If there's ever been a flash on camera its only ever been for triggering slaves.<br>

Old school I know but its worked..until now :)</p>

<p>I would highly recommend reading the entire Photonotes.org page on EOS Flash then! :) Very informative site.</p>