How to achieve this effect?

[Claudia_Neurojuice]

I might as well be talking rubbish - please correct me! - but I had imagined you only need to use slow sync flash and a "long" exposure to record an image like this one:
https://scontent-b-mxp.xx.fbcdn.net...=d7549a89455915c704d8a3f1c40bd18d&oe=5509E3A5
(Credits to Domininkas Zalys)

I have recently tried that at an indoor party and wasn't able to record the lights (without blurring the subject). What's the right technique? What did I do wrong?

 

[Buckster]

Without using the flash to light the subject, the image should be so dark that only the light trail shows up. The fact that the subject is blurry in yours indicates that the exposure was not dark enough to exclude him/her/it.

 

[Claudia_Neurojuice]

Thanks, Buckster - but I do want to include the subject! I would like to get both the subject, well lit and sharp, and some lights. I've seen this in many shots but I can't seem to figure out what's the correct balance between exposure and flash.

 

[photoguy99]

Set your flash power and aperture to a combination that will give you a good exposure of the subject.

Now set your shutter speed to -- with the aperture you have selected -- render everything EXCEPT the lights as black, or pretty much black, but which will give you a nice looking light trail. If the background is too well lit, this may be impossible. There's needs to be sufficient difference between the brightness of the lights of the brightness of the scene.

If there IS sufficient difference, you may still find that your shutter speed is not slow enough to give you good light trails. Stop down the aperture and pump up the flash power (or move the flash closer).

This is only going to be possible for certain combinations of actual lighting, and specific gear.

 

[qleak]

Thanks, Buckster - but I do want to include the subject! I would like to get both the subject, well lit and sharp, and some lights. I've seen this in many shots but I can't seem to figure out what's the correct balance between exposure and flash.

Buckster is right you should adjust the iso / shutter / aperture to expose only the lights then use then set the flash to correctly expose the DJ.

Set your flash power and aperture to a combination that will give you a good exposure of the subject.

Now set your shutter speed to -- with the aperture you have selected -- render everything EXCEPT the lights as black, or pretty much black, but which will give you a nice looking light trail. If the background is too well lit, this may be impossible. There's needs to be sufficient difference between the brightness of the lights of the brightness of the scene.

If there IS sufficient difference, you may still find that your shutter speed is not slow enough to give you good light trails. Stop down the aperture and pump up the flash power (or move the flash closer).

This is only going to be possible for certain combinations of actual lighting, and specific gear.

Couldn't he add a little more flexibility by knocking down the light a bit with an ND filter or polarizing filter if there is too much ambient light?

 

[photoguy99]

Sure, you can play some games with filters. Pretty much the same as stopping down, but maybe you're at the limit of your lens, OR you don't want to stop down that far. Good suggestion!

 

[Buckster]

Thanks, Buckster - but I do want to include the subject! I would like to get both the subject, well lit and sharp, and some lights. I've seen this in many shots but I can't seem to figure out what's the correct balance between exposure and flash.

The flash lights the subject in an instant, so that the subject is frozen. In yours, the subject is blurred because it's being exposed enough to show up throughout the time the shutter is open, not just when the flash is going off.