Canon 420EX question

[simann]

I have a Canon 420 EX flash unit, which I use with my 300D.

Could someone explain to me in plain English, in what circumstances

I should use either the ?Normal sync mode? or the ?High speed sync

mode?, or should I keep it on high speed all the time?

[rags]

Hi Simon,

 

Every camera has what is called a "flash sync speed" or "X-sync" and in normal mode the shutter speed used has to be equal to or slower than this. If you're using shutter speeds faster than the sync speed then you have to switch over to the high speed sync mode. Check this out to know why: http://photonotes.org/articles/beginner-faq/flash.html#xsync

 

raghu

[idoy]

Take a look at the <a href="http://photonotes.org/articles/eos-flash/#fp">PhotoNotes explanation of this issue</a>.

<br>

As long as you're using shutter speed below the x-sync limit of your camera, it doesn't matter what mode you're using. It matters only for shutter speeds above the x-sync.

[idoy]

I'm too slow...

[simann]

Thanks guys for your input, I have read the notes and it seems to me that apart from fill in flash at a narrow depth of field on sunny days, High speed sync is not much use. Or am I wrong?

I was under the impression that I could use it at higher shutter speeds to compensate for camera shake, when taking hand held shots of fast moving subjects in low light conditions.

[idoy]

Again, I recommend reading the <a href="http://photonotes.org/articles/eos-flash/">PhotoNotes flash photography guide</a> carefully. It's excellent, and will probably answer all your questions.

<br>

As for <i>using it at higher shutter speeds to compensate for camera shake, when taking hand held shots of fast moving subjects in low light conditions</i>, this isn't exactly right. But you can use the flash at slow shutter speed (below the x-sync speed). The flash will freeze the close object while allowing to expose the background properly (the background will suffer from camera shake, though).