When a wireless flash doesnt trigger properly...

<p>...what is it that I should check?</p>

<p>So Im using a Canon 500D with a 580EX II Speedlite. My radio triggers are Cactus V4.</p>

<p>My shutter is 1/125. What's confusing is that when I press the Cactus' test button, the flash fires every time. But when I press the camera's button to actually take a picture, the flash fires too late or not at all.<br>

I have used these radio triggers well with a Vivitar 285HV. So why no worky with 580EX II? :(</p>

<p>There might be a maximum shutter speed synchronisation above which the flash would not fire. What dies the cactus manual say? The cactus might work in test mode with weak batteries but do check the batteries on the sender and receiver.</p>

<p>How are you trying to trigger the EX? With a PC cable or mounted on the V4 hot shoe?<br>

If a cable then try another since the 285 has it's own. If hot shoe the contacts in the V4 maynot work properly with the 580. Have you checked a compatibility list on the Cactus site?</p>

<p>If the receiver LED is flashing when you press the shutter button then it sounds to me that you have a connectivity issue.</p>

 

<blockquote>

<p>What's confusing is that when I press the Cactus' test button, the flash fires every time. But when I press the camera's button to actually take a picture, the flash fires too late or not at all.</p>

</blockquote>

<p>Sounds to me that the connection at the flash is fine, transmitter is transmitting. You have an issue between the camera and transmitter. Is the hotshoe loose? Is the transmitter shoved too far forward? Is the center contact making a good contact between camera and transmitter?</p>