Long exposure Portrait with second curtain Flash - Advice.

[ilang]

Hi All

I have recently done a portrait shoot with the city lights as a background at night. The attached shot was a 10 Sec exposure on a canon 6D with a Canon 430EXii mounted on top. The Flash was on second curtain. If you look closely at the picture the models arm is ghost like. How do I overcome this problem. Was my flash not powerful enough to over power the 10Sec exposure? Would it help if I took the flash off camera and triggered it closer to the model? Or should I position the model away from bright background light.
Thanks for your help and thoughts

 

[Drizzt321]

Not having tried this technique, I don't think you have much of a chance without some extreme measures. You're model will have light spilling on her no matter what from the ambient light. So, perhaps you could have an extremely long exposure with very small aperture, and have the model walk in and assume her position just before the flash? That way any light reflected from her is minimal until the flash. Unless there are some tricks I'm not aware of, which easily could be.

 

[rs]

Its all about either reducing the movement, or proportionally reducing the amount of ambient light on what does move.

1) Get the model to move less for the exposure, reducing any motion blur
2) Get the model to stand in the shadows, so next to no ambient light hits her - then the flash will freeze her better
3) Use first curtain flash, a longer exposure and faster subject movement - 30 secs plus and brisk walking should do it, so next to no ambient light falling on her will affect the exposure.

 

[Drizzt321]

Its all about either reducing the movement, or proportionally reducing the amount of ambient light on what does move.

1) Get the model to move less for the exposure, reducing any motion blur
2) Get the model to stand in the shadows, so next to no ambient light hits her - then the flash will freeze her better
3) Use first curtain flash, a longer exposure and faster subject movement - 30 secs plus and brisk walking should do it, so next to no ambient light falling on her will affect the exposure.

#3 is sorta the reverse of my thought Only potential thing I can think of is that you'll need to look closely to make sure the background doesn't bleed through on darker fabrics/portions of the model.

 

[Ewinter]

Depending on the length of the exposure, just pop the flash more times

 

[c-law]

The problem with her arm ghosting is not from ambient light falling on her. Your flash doesn't need to be more powerful.

It is from her arm moving during the long exposure and allowing ambient light to burn through the flashed area because the arm is no longer block that light and create a silhouette (which is then filled in by flash).

It doesn't matter if you use first or second curtain sync (or even hold the flash in your hand and manually trigger it by the test button), you do not want to keep her moving. You want to set her up in a pose that she can easily hold without swaying or moving for the duration of your exposure.

If she remains perfectly still she blocks the light just like when you create a silhouette. That will allow the flash to fill her in without ghosting.

 

[ilang]

Thanks to all for your comments.
c-law , I think the movement does make sense I do have a number of picture with no blur , maybe she was in more comfortable positions.
I guess the best solution is bump up ISO or F to reduce the exposure time so less chance of motion blur.

 

[wickidwombat]

The problem with her arm ghosting is not from ambient light falling on her. Your flash doesn't need to be more powerful.

It is from her arm moving during the long exposure and allowing ambient light to burn through the flashed area because the arm is no longer block that light and create a silhouette (which is then filled in by flash).

It doesn't matter if you use first or second curtain sync (or even hold the flash in your hand and manually trigger it by the test button), you do not want to keep her moving. You want to set her up in a pose that she can easily hold without swaying or moving for the duration of your exposure.

If she remains perfectly still she blocks the light just like when you create a silhouette. That will allow the flash to fill her in without ghosting.

Not quite true
Too much ambient light on the model will cause this too

My rules for doing this
1 make sure the model in as little ambient light as possible a good way to check is to take a shot with no flash ey should pretty much be a complete siloette
2 try keep the exposure to 5 seconds or less 10 is too long its too hard on the model I've found 5 is really the limit especially if you are takimg quite a few shots
3 camera on tripod remote trigger and 2 second timer I run out with the flash and point it where I want while the timer is going
4 make sure your expose balance is right that shot has too much flash power and being direct didn't help probably needed to be -2\3 to -1 flash ec on it

 

[Ripley]

CR0

 

[Schruminator]

To me it looks like the ambient/city lights are shining through her (I see some lit up windows that are clearly on top of her head).

Sort of along the lines as the other guys, it looks like she's moved at some point during the exposure. Basically I'd open your aperture or bump your ISO up to allow for a shortened exposure time. With that, your model is less susceptible to move and cause the problems.

Or, if you're already shooting at your camera's limits, try shooting when there is still a hair more light in the sky. You'll still get a similar nighttime look, but there should be more light in the frame to work with.

 

[AprilForever]

While you are at it, I would CTO gel your flash, to get the color temperature on your model a little less cool, a little more natural to the surroundings looking.

 

[LewisShermer]

Just a thought, how come you used 2nd curtain sync? surely you should use 1st curtain with this set-up so the model is exactly how you see her through the viewfinder at the beginning of the exposure rather than leaving it up to how she's randomly posed after 10 seconds? she also needs to be briefed to stand still for the 10 seconds thereafter to avoid "see through arm". But to be fair, first curtain sync would overcome that as she'll be the most brightly exposed part of the photograph from the outset. the only effect she'll have through movement is making the background darker. In fact, thinking about it, you could shoot, she could jump out of frame and no one would be any the wiser.

 

[wickidwombat]

Just a thought, how come you used 2nd curtain sync? surely you should use 1st curtain with this set-up so the model is exactly how you see her through the viewfinder at the beginning of the exposure rather than leaving it up to how she's randomly posed after 10 seconds? she also needs to be briefed to stand still for the 10 seconds thereafter to avoid "see through arm". But to be fair, first curtain sync would overcome that as she'll be the most brightly exposed part of the photograph from the outset. the only effect she'll have through movement is making the background darker. In fact, thinking about it, you could shoot, she could jump out of frame and no one would be any the wiser.

No it won't go try what you just suggested and report back

 

[ScottyP]

Because of the lights behind, I don't think you could do the longer exposure with model jumping out thing. She may not have motion blur, but the city lights would burn through her body. With this background I agree with the shorter exposure and keeping extra ambient light off of the model. I also agree that the 1st curtain flash will let the model know when to pose.

If she were twirling a sparkler or a LED light or something to create light trails, I would suggest the opposite; long exposure, heavily underexposed to reduce ambient light and ghosting, and then 2nd curtain sync.