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Alex1984

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Alex
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...probably very basic question but I am a noob. I have seen some pics where there are people (at a gig so obviously not still) and the background has the impression that it has had a long exposure as there are light trails etc...But the people still look pretty much in focus...is this achieved by moving the camera...?

Many thanks
 
You use flash, rear curtain I think. I personally hate those types of images, but everyone has their own taste.

The flash freezes the subject but because it doesn't fire until the rear curtain is about to cover the sensor, you also get the light trails from what happened before the flash fired.
 
TCR4x4 said:
You use flash, rear curtain I think. I personally hate those types of images, but everyone has their own taste.

The flash freezes the subject but because it doesn't fire until the rear curtain is about to cover the sensor, you also get the light trails from what happened before the flash fired.
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Yep, rear-curtain, also called 2nd-curtain, flash. What you see is the "without flash" images (long exposure so light trails) plus the flash exposure. Since most flash durations are around 1/1000 of a second object illuminated by the flash will appear as if a much shorter exposure was used.
 
RicherSea said:
Yep, rear-curtain, also called 2nd-curtain, flash. What you see is the "without flash" images (long exposure so light trails) plus the flash exposure. Since most flash durations are around 1/1000 of a second object illuminated by the flash will appear as if a much shorter exposure was used.
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You don't need second curtain sync for that. In fact, it's often a disadvantage.
 
HoppyUK said:
You don't need second curtain sync for that. In fact, it's often a disadvantage.
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ummm.....

If you have people moving in the frame then you either need to use second curtain or to drop the ambient exposure so low that they don't have any motion blur at all. Given that the OP's question related to gig photography I'm assuming he didn't want just light trails in the background, but some ambient image as well. If he does that with first curtain he's going to have motion blur going backwards from his foreground subjects.

If you are genuinely after the only background objects being light trails then yes, first curtain is as good. I can't think of why it would be better, but I've never tried, so it might well be.
 
RicherSea said:
ummm.....

If you have people moving in the frame then you either need to use second curtain or to drop the ambient exposure so low that they don't have any motion blur at all. Given that the OP's question related to gig photography I'm assuming he didn't want just light trails in the background, but some ambient image as well. If he does that with first curtain he's going to have motion blur going backwards from his foreground subjects.

If you are genuinely after the only background objects being light trails then yes, first curtain is as good. I can't think of why it would be better, but I've never tried, so it might well be.
Click to expand...

Second curtain sync is only useful when the direction of movement is a) important, and b) predictable. With most club photography, it isn't.

The downside of second curtain sync is that if the ambient exposure time is longish, then it's harder to capture sponantious gestures and movements, becuase the flash doesn't fire when you press the release. However, the pre-flash does fire immediately (when using auto-flash, which is usually a good plan when distances are changing all the time). This sometimes means that you capture the subject blinking after the pre-flash, or they move after the pre-flash because they think the picture has been taken.

Pros and cons. Second curtain sync has got a bit of a reputation as some kind of magic bullet for slow-sync flash. Some folks believe it 'overlays' the ambient exposure because it goes last. That's simply untrue, and for those other reasons it can be a liability.
 
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