What is reason for first cutain?

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I own an Elan 7e which gives me the option to use second curtain flash sync with my 420EX. This means that the flash fires right before the shutter closes rather than immediatly after it opens. This causes light trails and blur to look more natural. This seems like a great idea. Is there any reason for me to EVER use first curtain sync?

-- shadow (mshadow818@msn.com), March 20, 2002

Answers

Shadow,

I agree with you. However, if you wish to take advantage of High Speed Synchronization Flash, you will NOT be able to do so while using Second Curtain Synchronization. So, yes, there is a reason to use first curtain.

Here is a great site on the EOS flash system

http://teladesign.com/photo/eos-flash/

Enjoy, Roger

-- Roger Shrader (rashrader@hotmail.com), March 20, 2002.


In addition to FP flash there's another reason that cameras default to first curtain sync operation.

Let's say you take a photo with a slowish shutter speed. The problem with second curtain sync is that you won't necessarily successfully capture the scene because the flash occurs some time period *after* you push down the shutter release. And during that time people can move, scenes can change, etc.

With first curtain sync the flash fires pretty well immediately after you press the shutter release, so you're certain to capture the scene as you saw it through the viewfinder.

-- NK Guy (tela@tela.bc.ca), March 21, 2002.


As far as FP flash goes, the notions of first and second curtain sync don't apply - the flash fires throughout the whole exposure, from when the first curtain starts to open unitl when the second curtain finishes closing (it's not continuous; rather, it's a series of flash bursts at a rate of tens of thousands of bursts per second).

I have an Elan II and 380EX (neither one in use any more) and an Elan 7e and 420EX. Both combinations have no problem at all going into FP mode while the CF is set to do second-curtain sync.

-- Steve Dunn (steved@ussinc.com), March 21, 2002.


>Both combinations have no problem at all going into FP mode while the CF is set to do second-curtain sync

Right. But second-curtain sync doesn't make sense with FP mode as you say. So the gear is in effect reverting to first-curtain sync mode by starting the flash firing when the first curtain opens.

-- NK Guy (tela@tela.bc.ca), March 21, 2002.


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