russell_bastock

<p>Thanks all (particularly Craig for detailed response). This feedback has been invaluable. I was shooting a busy event in shifting late afternoon light, so was trying auto modes to compensate but ran into problems with low shutter or overexposure. Now I can make more informed decisions. I'm not shy of manual but was seeing how well (or not) auto modes could handle the conditions, but not really knowing how they operated.</p>

<p>I want to know if people have found specific changes to their photos using Speedlights/Speedlites either Tv or Av as opposed to P. I've heard P is not recommended for fill flash, especially in low light such as dusk. Or do some prefer using M for the camera and leave the flash in E-TTL mode? I'm interested in what pro photographers or photojournalists prefer or find more reliable.</p>

<p>There was an issue with the 580EX where the tube was faulty so occasionally the flash would dump its entire charge and 'snow' out the image (if shot at night). If this issue happens randomly then get your unit checked by a repairer.</p>

<p>Well this was unexpected. I visited my camera repairer and he said the ON position only stops you changing the aperture via the Quick Control Dial! As viewed in the top LCD. I thought it was supposed to enable/disable the entire wheel! I think what must be happening is somehow I've bumped the multi-controller and then the Quick Control Dial which has changed settings on the rear screen functions matrix. That was a long journey to discover that.</p>

<p>Thanks for the clarification Colin. As I suspected, the switch is not functioning correctly. The Quick Control Dial changes settings in the ON and _/ positions. I'll need to get it fixed. If that doesn't completely solve the issue, gaffer taping the dial may be the only safeguard.</p>

<p>I took my recently acquired 5D Mk II out on a busy shoot and a couple of times I found that the exposure compensation had changed without me accessing it. It took me a while to notice it. Once it was + 1/3, then another time it was - 1 2/3rds. I've no idea how this happened.<br> I know at least once I accidentally span the Quick Control dial while moving about with my camera. My guess is that I must have bumped the the multi-control button then the dial. But I've not been able to confirm this. Any other sources of this error?<br> <br />The manual says that the On switch has two functions, the _/ setting and the On setting, but I see no difference between the two. In either mode the dials still change settings. I'd be interested to hear of other people's experiences.</p>