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Long exposure subject ghosting

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I recently played with some long exposure (25 minute) shots where I popped the

flash to freeze a subject as he passed through the frame. The results were good

for a first try, but there are some things I'd like to change. Mostly, I'm

getting some "ghost" effects where the light doesn't hit my subject enough. I'm

curious how to get light on the black pants so they're not transparent

(possible?) without blowing out his face and jacket. Am I best off having him

wear a different color besides black?<div>00P4LJ-42749884.thumb.jpg.6e9549a176a5776f3ca7bac35ffa3af6.jpg</div>

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"...... I'm getting some "ghost" effects where the light doesn't hit my subject enough..... "


You're getting "ghost" effects because your ambient exposure is too bright on the snow behind the subject. Use less ambient exposure with a faster shutter speed.


"......I'm curious how to get light on the black pants so they're not transparent (possible?) without blowing out his face and jacket...."


More light on the black pants won't work because the bkgd already has exposure from the ambient light and is bleeding through the dark shadow areas of the flash exposure. You just happen to see it through the subject's pants because they're a shadow area.


"......... Am I best off having him wear a different color besides black?..."


Yes a light color for the pants would help up to a point. You really need to lower your ambient exposure so there is less light recorded on the snow behind the subject.

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This might be a crazy idea....


What about an ND grad for the bottom portion of the frame? It's opposite to how you would normally use one, but it would cut down on the foreground exposure. If you don't have an ND grad filter, holding a black card in the lower half of the frame would also block light and wouldn't interfere with lighting the skier. Just hold it there for maybe half the exposure and then take it out when exposing the skier.


You could also do a couple weaker handheld flash pops to light more of the foreground.


Your skier buddy needs to carve a harder turn and really throw up some spray for added drama.

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Benjamin, you're correct in thinking that lighter clothing on the person would improve the situation. The lighter his clothes are, the greater the percentage of the exposure will be him, vs the background. Also, planning the shots so he will be against a dark background instead of the snow would help.
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With multiple exposures, light always shows through dark, regardless of which was in front of the other. If you have a black object in front of a white background, the background will show through.


The solution is "don't do that". Make the background darker than the skier. If you can't have him wear light clothing, you'll have to change your camera angle so that his entire body his against the dark trees in the background. Yes, an option is to reduce the ambient exposure enough so that the snow looks darker than his dark pants, but if you reduce ambient so that snow looks dark, you pretty much have to eliminate all ambient light.


Semi-related, note that whenever you see multiple exposure motion studies (<a href="http://web.mit.edu/Edgerton/">Doc Edgerton's work</a> has some classic examples), it's always a white moving object photographed multiple times against a dark background. That's not coincidence. In multiple exposures, white always covers black, regardless of which is in front.

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Since you are doing a long exposure I presume that you are using a tripod. One simple way

to solve the problem is to take a "normal" photograph of the skier with a flash. Then without

moving the camera, take your long exposure images. Combine the two images in Photoshop.

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Thanks for all of the suggestions! I'll try to respond to all of them:


Thanks to those that confirmed it's a problem of black on white. It's a tough shot to go out and experiment with because it takes so long! I think I'll try dropping the camera angle or working terrain into it so that he's against the dark trees next time. ("Don't do that") as well as get him in some lighter pants.


I'm not sure I want to drop the ambient exposure with a shorter shutter speed. If anything, I'd like the shutter open longer to capture longer star trails and maybe even brighten up the snow a little. A GND sounds like a cool approach. I hadn't thought of that.


Re: lighting - I'm not sure how many pops I want to brighten up the foreground. I think next time I may put a slave on his back pack pointed at the trees to provide a little more separation. I'd also like to elevate the main light and make it larger. This one was just a 430ex hand held over my head. I'd like to get it up a little higher and make it larger to make the coverage a little more even.


The Photoshop solution would work OK, but there's something special about getting it done in camera. Maybe next time we'll take frames for both techniques and compare the results.


Re: the snow-spray, when the sun goes down, corn snow turns back to ice. The sun had been down for ~2 hours when we started this exposure, so the trails were rather firm thus no snow spray. We're really working out the technique for other days when the snow returns. And maybe for biking season!

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