front vs rear Shutter Sync?

Ben-BSH

Ben-BSH

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Ben
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Out of interest, for other users of flash out there, do you use front or rear shutter sync for your portraiture work and why? I was thinking the other night, I should probably switch to rear to eliminate small amounts of blur at speeds lower than my max sync. but wondered if there were any downsides to this.

Thoughts?

Thanks :) Ben.
 
Rear curtain will not do anything to eliminate blur. Use first curtain in most cases, it makes timing infinitely easier.

Whenever the flash fires during your exposure, you still have the same amount of ambient light, and the same amount of flash light.

If your subject is moving the only difference will be the apparent direction of the blur. First curtain will give you a frozen subject followed by blur, and rear curtain will give you blur leading into a frozen subject which can look more 'natural' for someone running, etc.

If your subject (or camera) is not moving, the only difference will be absolutely nothing. (Apart from possibly confusing your subject as they don't know when the flash will fire with longer exposures). :thumbs:
 
If you want to capture blur and movement caused by ambient then rear otherwise I don't see any point using anything other than first curtain
 
Fair enough, I'm sure i read somewhere rear curtain sync would paint a "frozen" subject over the top of one who had moved ever so slightly, basically reducing blur, clearly i read wrong! :)

Thanks for the info! that's why i asked the question ;)
 
Second/rear curtain sync is widely misunderstood. It can be brilliant but it's no magic bullet and there are good reasons why first-curtain sync is the default.

For example, second-curtain sync doesn't work at all until shutter speeds drop below 1/30sec, and even then the flash fires well before the end of the exposure - it's more like middle-sync. Only at significantly longer speeds does the flash get relatively closer to the end of the exposure. Pocket Wizard's Mini/Flex system can tighten this up usefully, but the OEM defaults are sloppy.

There is a widely held belief that by firing the flash last it somehow overlays the flash image more prominently. This is untrue - if you want a clearer flash image, then it must fall over a dark area of the background.

There are other problems. With longer shutter speeds, second-curtain sync makes timing the moment much more difficult, and fleeting gestures and expressions are hard to capture. When used with auto-TTL enabled, the pre-flash makes subjects think that the picture has been taken, and they move. And when the pre-flash and main flash are quite close together, there's a good chance you'll capture the subject blinking.

On the other hand, second-curtain sync works really well if your subject is a) moving, and there is some usable ambient light, b) it's moving in a predictable direction, and c) the direction of that movement is important. In that situation, second-curtain sync will put the ambient blur behind the subject, and the subject will be less obscured by that ambient blurring. Well illustrated in comparison graphics here http://neilvn.com/tangents/first-curtain-sync-vs-rear-curtain-sync/
 
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