Avoiding Ghosting when using Strobes and Ambient Light

I think the flash duration on my pack at

max is around 1/1200. Not as fast as a

speed light.

Flash duration has nothing to do with this type of ghosting. The examples shown happens after the flash exposure and is caused by the

back ground ambient light being equal to or brighter than your flash exposure.

<p>Great topic! What Calderon has is <strong>classic ghosting</strong>. Its caused by a conflict of flash/ambient light. For <em>whatever</em> reason you have ambient light coming in after your flash. It usually always on the edges (looks like a black contour line). Any number of reasons could cause it. Slow shutter speeds with flash and fast subject movement is usually the main reason for ghosting. You say you have a shutter speed of 1/250s and aperture of f16 so that <em>should</em> cut down most the ambient... so my guess is camera shake/subject movement. Michael has the closest answer...</p>

<blockquote>

<p>....the ambient light exposing the subject becomes silhouetted on the outer edges of the body by the open sky as the subject moves or the camera (moves).</p>

</blockquote>

<ul>

<li>Shoot with the highest max flash sync speed (this may not work if you have a slow sync camera) or use high speed flash sync flash guns.</li>

<li>Shoot with a tripod or if handheld a standard or medium-telephoto lens to avoid <em>camera shake</em>. No more than 135mm lens hand held if your flash sync speed is only 1/250s or less.</li>

<li>Make sure your subject is perfectly still.</li>

<li>Shoot your subject in the shade, so only fast flash duration will work for you instead of slow sync speed.</li>

<li>Overpower the sun /ambient light /background light with flash 1-2 stops + , where your flash is the key light. This takes a lot of wattage!</li>

<li>Small aperture to cut down ambient light /background light the main cause of ghosting.</li>

<li>Lowest ISO film speed available</li>

<li>Use a second strobe light or light source to light the edges.</li>

</ul>

Is there a second flash to fill in the dark side? If it was aimed at the dark line and synced properly then it needs to be raised in power or the main light lowered to get down to a 2 to 1 ratio. If there is no second flash and the main light is very much above ambient and the main is off camera center good chance for dark line.

Randy i dont understand your question. Are u asking if you can use a second flash aimed to the side of the subject to

eliminate the ghosting? If so the answer is no. You can have ten flashes and this will still happen. There is too much over

thinking and too much technical thinking going on. Lets see if someone can recreate this ghosting then fix it and post the

pictures.

Michael,

 

Flash duration has nothing to do with this type of ghosting. The examples shown happens after the flash exposure and is caused by the back ground ambient light being equal to or brighter than your flash exposure.....

 

I agree with your statement:

 

...back ground ambient light being equal to or brighter than your flash exposure.....

 

so if ambient light is exposing the dark line it is because the main strobe is not hitting it or the fill (if any) is not strong enough. I don't have the equipment I want to show this but I will try to cobble up something. BTW if you look at the OP's portfolio, you will see the same dark line between the seated blond's arms from the ovehead studio strobe. In this instance it looks normal because that is the way an overhead source (sun, normal house lights etc..) would light the scene.

<p><img src="file:///Volumes/Local/Users/Mike/Desktop/_Q7T4598.jpg" alt="" />Ok I found some examples of ghosting but with a different senario. My subjects was not against the open sky but rather the ambient light is striking parts of there body (hands) My camera was set to 640iso F8 @ 125 so here the blue spot light mixed in with my flash exposure and instead of a black contour line I got a blue one. If the light was white it would have been white or more flesh toned. </p><div></div>

<p><img src="file:///Volumes/Local/Users/Mike/Desktop/_Q7T4598.jpg" alt="" />Ok I found some examples of ghosting but with a different senario. My subjects was not against the open sky but rather the ambient light is striking parts of there body (hands) My camera was set to 640iso F8 @ 125 so here the blue spot light mixed in with my flash exposure and instead of a black contour line I got a blue one. If the light was white it would have been white or more flesh toned. Oh and by the way there is more than one light hitting the subject at different angles.</p>

<p>Randy,<br>

You cant expose the dark line with a flash. Think of it as two separate exposures or even pictures. The first picture is exposed by your flash and the second exposure is the ambient light. Now in this senario if you took this same picture again without flash you would have a siloette. Now place your flash picture directly over the siloette and you have a perfect picture. That is what he would have gotten if he used a tripod or at the very least held steady. Since there was movement on the cameras end it caused your two pictures to slightly move apart and therefore showing the siloetted picture below your flash picture. You can tell which direction the movement was based on which side the black line (siloette) is on. There will never be a black line going all around the body. Unless you zoomed in during your exposure. Just guessing here.</p>

<p>Randy,<br /> I reread your post and you asked if the ambient light is hitting the subject. In my example it is doing just as you say. You can see that my flash is also illuminating the same area properly exposed. It is only because the two diffent light sources are at equal value that this happens. Even though the shutter speeds are fairly fast (200) It is because the flash exposure is going on and off way before the shutter closes and therefore allowing any available light that is in equal value or brighter to expose the picture.</p>

<p>Think of it this way, Ghosting is just a blurred picture caused by movement. Generally we see this when are shutter speeds are too slow for the moving subject. Now take those same exposures and add flash at the same f stop and you will have a flashed in subject with a blur or movement from the ambient exposure. Of course the f stop would be 11 for those of you who are thinking two light sources at f-8 added together is 11. </p>

I always thought I wouldn't need a

tripod when using flash. Is like every

scenario is a bit different eh.

Michael, I kludged up an example but it is not very elegant. I stuck white paper around a pencil basket to get a curvature similar to the OP model's hand. Then I took an ambient light shot at F2.8 so the curvature could be seen. Notice that the right side of the basket is brighter the the side facing the camera. Then I attached a Sunpak 544 and held it as far camera left as possible. In the resulting pic the dark line can be seen. The pictures were posted with no editing except for cropping and resizing. I reduced the exposure by several Fstops and the closer the flash got to ambient, the lighter the dark line became. If I had a second flash pointed at the dark line (this is why I said I didn't have the equipment) it would fill in the area not hit by the Sunpak and not be dark. Maybe you or another PNetter can try this.

 

Regards,

 

Randyc<div></div>

Flash shot<div></div>

Michael, in your example it sure looks like movement is the culprit but at 1/125 seems like it wouldn't be a factor.

<p>Randy good effort but the black line you have is only the shadow from the flash. You were right when you said looks like movement is the culprit. 125 is only one stop faster than 60 and when people are dancing they are moving and jerking pretty fast. The flash will freeze even at 1/4 sec in total darkness but once you introduce ambient light all bets are off. Thats why I said it is like taking two pictures one with flash and the other ambient. redo your shot and jerk the camera as you take the picture and you should see the movement on one side of the flashed picture. By the way your flash is way over exposed. your flash should be equal to your ambient.</p>

<p>MM gave an excellent description of this phenomena:<br>

<em>"... Think of it as two separate exposures or even pictures. The first picture is exposed by your flash and the second exposure is the ambient light. Now in this scenario if you took this same picture again without flash you would have a silhouette. ..."</em></p>

<p>The only aspect of the argument that doesn't seem to have been explicitly discussed is the requirement that for maximal "dark halo" effect, without the flash, the side of the subject towards the camera should be significantly underexposed. In other words, the ambient light should be coming predominantly from the rear of the subject, and hence make the subject (without the flash) somewhat silhouetted. This isn't an absolute requirement, but it makes the effect more obvious and its explanation clearer. </p>

<p>Randy, try your experiment again, but this time, have the continuous ambient light illuminate only the background. Have the front of the pen holder in shadow in ambient light. Then turn on your flash (aimed at the front side), balance the exposures, and jiggle the camera. The dark halo should be very obvious. </p>

<p>HTH, </p>

<p>Tom M</p>

 

<p>Thank you Tom for that detail. Yes the subject should be in shade or underexposed a couple of stops minimum. Here is another example where subject is illuminated by available light and flash balanced yet with movement you get the other type of ghosting without the dark edge. The subjects are under an overhang maybe a stop or so under from the background and the flash balanced it. Yet with subject movement there is a slight ghosting in the fingers. camera data f8 @ 80 400iso 105 lens.</p><div></div>

<p>i cant upload 2 pictures at once</p><div></div>

<p>So, how did Annie get a balanced flash to ambient ratio?<br>

I shot this image yesterday.<br>

No Tripod - ISO 200 - f/5.6 - 1/125th <br>

Ranger RX measured at 60% and ambient at 40%</p><div></div>

<p>Calderon your picture looks good. Your subject look like she was standing still. The short answer is As long as you can freeze subject without flash then you should be fine when you balance the flash. That is the real key point. So if you get movement without flash then you will get that ghosting when you balance the flash. The flash duration is in micro seconds much faster than 200 sec. The other variable is the focal length of the lens which can cause movement from the camera if the shutter does not equal or pass the focal length of the lens.</p>

<p>Thanks Michael! I will continue to practice this situation. Thanks for your samples too.</p>

<p>In my previous post, I described an experiment that should show the black halo effect. To make a long story short, I couldn't resist doing the experiment myself. </p>

<p>The experiment produced three photos. Each was taken as described in my previous post. In the first, I was panning slowly in one direction. In the second, I panned much faster in the same direction, and in the 3rd, I reversed the direction of panning and slowed back down.</p>

<p>The best places to see the dark halo-ing is where the yellow pencil and the white pen on the RHS of the frame are against the yellow lamp shade in the background. In the 1st image, the dark halo is on the LH edge of the yellow pencil. In the 2nd, the dark halo becomes very diffuse because of the speed of panning (but is still on the same side), and in the 3rd, the dark halo is on the RH edge of the yellow pencil. </p>

<p>HTH,</p>

<p>Tom M</p><div></div>

<p>.</p><div></div>

<p>..</p><div></div>