How to prevent ghosting with slow shutter speeds??
/forum/topic/1170605/1

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hondageek
Registered: Aug 16, 2004
Total Posts: 868
Country: United States

^ Yup. 2nd curtain sync has no effect on motion blur other than making it before or after the subject's direction of travel.



alohadave
Registered: Jul 26, 2005
Total Posts: 842
Country: United States

Graystar wrote:
jared_irl wrote:
The rear curtain will at least freeze the subject on top of the blur so they don't appear to be disappearing.

Rear curtain doesn't do that either. There's no layering of light on the sensor...the blur is the same regardless of when the flash fires. The only difference is the location of subjects...caught either at the beginning of their movement with normal flash or at the end of their movement with rear-curtain flash.


With people's normal action to break the pose when they see the flash, rear curtain minimizes blurring on people only because the flash is at the end of the exposure.



no_surrender
Registered: Apr 23, 2011
Total Posts: 1128
Country: Italy

Thanks all for helping clarifying why I was having the issues I had.

BrianO, I deleted the images from the thread in the People forum and from the gallery I created on my Smugmug page. It's safe to say I'm pretty embarrassed with the outcome of these photos and I'd like to prevent anyone from stumbling on them for now.

alohadave, your comment makes sense and would have probably at least helped.

hondageek, I do know I can stop action in a completely dark room since no ambient will be recorded as long as shutter speeds are high enough to keep anything from registering. My intention was to expose for ambient and light Santa and the kids which means the room couldn't be completely dark.

I made several mistakes with my setup, pretty much in every part of the exposure triangle. This has definitely been another learning experience, but one in which I volunteered for and am praying nobody asks me for the images since there were a lot of other people there taking pictures...just not with a lighting set up.

On the one hand I'm pretty discouraged, but on the other I'm motivated to figure this out to prevent it from being such a disaster in the future.

Thanks again! -Kevin



BrianO
Registered: Aug 21, 2008
Total Posts: 8454
Country: United States

no_surrender wrote: ...On the one hand I'm pretty discouraged, but on the other I'm motivated to figure this out to prevent it from being such a disaster in the future.

Noli arrogantium permittere te terere.

Keep at it, and don't allow yourself to be discouraged. The ones I saw before you took them down weren't as "disasterous" as I think you feel them to be.

What got in your way here was just not realizing that exposure speed was a matter of both flash duration and ambient exposure time.

Mixing ambient and flash is one of the harder things to master. The key is to remember to consider the basics first: composition still comes first, depth of field is still controlled by aperture, and exposure speed still controls motion. Pick your chosen parameters first, then light to follow that...not the other way around.

Good luck, and keep shooting.



no_surrender
Registered: Apr 23, 2011
Total Posts: 1128
Country: Italy

BrianO wrote:
no_surrender wrote: ...On the one hand I'm pretty discouraged, but on the other I'm motivated to figure this out to prevent it from being such a disaster in the future.

Noli arrogantium permittere te terere.

Keep at it, and don't allow yourself to be discouraged. The ones I saw before you took them down weren't as "disasterous" as I think you feel them to be.

What got in your way here was just not realizing that exposure speed was a matter of both flash duration and ambient exposure time.

Mixing ambient and flash is one of the harder things to master. The key is to remember to consider the basics first: composition still comes first, depth of field is still controlled by aperture, and exposure speed still controls motion. Pick your chosen parameters first, then light to follow that...not the other way around.

Good luck, and keep shooting.



Thank you for the encouraging words! Truth be told, I really needed that today...I'll keep pushing.

Kevin



Rodolfo Paiz
Registered: Jan 07, 2007
Total Posts: 9620
Country: United States

I haven't seen your photos, so I'm speculating -- but probably not far off -- from what I've read in this discussion.

Your simplest and most basic problem was that you needed a lot more light (ambient, or carefully-placed by you), or you needed a much higher ISO. Instead of 0.8s f/8 ISO 250, you'd have gotten much better results with (for example) 1/60 f/4 ISO 3200. With proper flash exposure on your subject, and ideally a colored gel on your flash to make its color match the ambient a little better, I think you'd have been much happier. You could also have placed a second flash somewhere, aimed at a wall or ceiling, just to add some overall light to the scene and allow you an even faster shutter speed or a smaller aperture.

Let me also add a little practical advice on how I'd approach a situation like this.

First, I know that Nikon's Auto ISO is very reliable and effective in all situations... except when flash is used. So I'd first turn my flashes off, turn Auto ISO on, set Shutter priority to 1/200 for nice crisp people, use whatever aperture I wanted (say, f/8 in your case), make sure I'm shooting RAW so I can get cleaner images and adjust WB later without penalty... then take a test shot. That test shot will tell me what ISO the camera recommends. In your situation, that would likely have been ISO 6400 or so.

Now that I know just how dark it is out there, I would choose an ISO and set it manually. For your 5D2, I would have probably set it at 3200 initially. Now take that second flash I mentioned earlier, pick a spot for it and set its power manually (probably at 1/4 power initially), and set it to be triggered optically (it'll fire when it sees another flash go off). Take a second test shot, which is now probably too bright. Adjust your ISO and the manual flash power until you get a look you like for the scene.

The first time you do this, you may need longer; but with a little practice, it'll all take less than 5 minutes. Finally, I'd put my camera on manual with my chosen shutter, aperture, and ISO settings, but leave my on-camera flash on TTL with a -0.3 or -0.7 FEC to make its influence more subtle. Now, fire away.

The approach above is simple and will not yield perfect results... but it should be pretty good and pretty reliable. A good diffuser for your on-camera flash should be a big help, the colored gels for the flashes are a huge help, and more flashes or lights would have been a godsend to you.

But remember, sacrifices and compromises are inevitable. Making your sacrifices and compromises wisely will do wonders for your images. For example: noisy and grainy is better than blurry: use whatever ISO you have to use to get a reasonably sharp shot. Also, shallower DOF (say, where the Christmas tree in the background is slightly to reasonably blurred) is better than a blurry child... and might even make your image look better. Think about each variable. Take what you can, give where it makes most sense.



Rodolfo Paiz
Registered: Jan 07, 2007
Total Posts: 9620
Country: United States

P.S. Never become discouraged... every day and every shoot is a learning opportunity. If you want to practice this kind of situation, just turn on the bedside lamps in your bedroom and nothing else, then put a light-colored stuffed animal in a chair. Simulate, practice, and remember that LIGHT is everything in photography: how much, what color, how bright, and where it shines (as well as where it doesn't shine).



no_surrender
Registered: Apr 23, 2011
Total Posts: 1128
Country: Italy

Thanks Rodolfo for the advice. It is much appreciated!

Kevin



Rodolfo Paiz
Registered: Jan 07, 2007
Total Posts: 9620
Country: United States

So when's the next shoot?



no_surrender
Registered: Apr 23, 2011
Total Posts: 1128
Country: Italy

Nothing planned right now...just need to find time to practice.



no_surrender
Registered: Apr 23, 2011
Total Posts: 1128
Country: Italy

Still having a terrible time properly mixing *low light* ambient and flash. Just finished a bar type scene at ISO 400 and still ended up with a >1" shutter...yeah yeah, it was at f/11 though. I wanted a nice deep dof to capture the environment, but still ended up with more ghosting than I would have liked.

I should clarify, I actually WANTED some ghosting, just not in the main subject. I was trying to create a solid subject in the foreground with the "customers" being subjected to motion blur from the slow shutter. Wondering if I should be adding a second light to help freeze the main subject. This is a whole lot harder than I thought.

I know I could have bumped my ISO quite a bit more, but am still pretty hesitant to do that. Just need to keep practicing.

Kevin



BrianO
Registered: Aug 21, 2008
Total Posts: 8454
Country: United States

no_surrender wrote: I should clarify, I actually WANTED some ghosting, just not in the main subject. I was trying to create a solid subject in the foreground with the "customers" being subjected to motion blur from the slow shutter. Wondering if I should be adding a second light to help freeze the main subject. This is a whole lot harder than I thought.

You can't really freeze the main subject and blur the other people if the subject is receiving the same ambient light that's lighting the others. If so, the long shutter speed will record the subject's motion just as it does the others'.

Only if the subject is in the dark and the BG is in light can you can drag the shutter to bring up the BG exposure and use flash to light the subject without blur.



Rodolfo Paiz
Registered: Jan 07, 2007
Total Posts: 9620
Country: United States

no_surrender wrote:
Still having a terrible time properly mixing *low light* ambient and flash. Just finished a bar type scene at ISO 400 and still ended up with a >1" shutter...yeah yeah, it was at f/11 though. [...] I should clarify, I actually WANTED some ghosting, just not in the main subject. I was trying to create a solid subject in the foreground with the "customers" being subjected to motion blur from the slow shutter. Wondering if I should be adding a second light to help freeze the main subject. This is a whole lot harder than I thought.


Practicing needs to involve some exploration and experimentation, and then learning from both the failed experiments and the successful ones. It's not that hard, but you're too afraid of failure, and so you're making things harder on yourself because you're limiting your opportunities to learn.

Shove the ISO -- hard -- straight to ISO 3200 and shoot that way for at least half the session. Just do it. Then work on post-processing those images and see how they're different, how you need to treat them, and just how usable they are. Remember to print a few, don't just look at them on-screen. Noise is invariably less of a problem in print than you'd think from first looking at the file on-screen.

The higher ISO will immediately bring your SS back to around 1/8" which is much more manageable. Also, because the capture is 8x more sensitive (3200 vs 400), you'll need 1/8 as much flash power to get the same exposure. Flashes provide less power by limiting duration, which means you'll get a sharper subject since the light is on for a shorter time (at 1/8 power, something like 1/5000"). You don't necessarily need a second light.

You can also reduce ghosting on your main subject by putting as little ambient as possible on him/her and lighting him/her almost exclusively with the flash. If you have a subject in near-darkness, lit by flash, you can have a long-ish shutter speed to blur the background motion while only minimally blurring the subject. Remember to tell them to hold very still... every little bit helps.

Lastly, remember that DOF is something that you may need/want to sacrifice. I'd prefer the background not to be crisp and sharp, but just a little OOF to create a little separation from the main subject. Do some test shooting (again, deliberately trying things that may not work to learn from them) at f/11, f/8, f/5.6, and f/4, and don't worry about your subject on these. Think only of how the background looks and how blurred it is or isn't, and which "look" you like best. You may prefer f/4 (I would). Or, you may still prefer f/11 but decide that you can tolerate f/8... and right there you've just gained one full stop of light, meaning your shutter speed doubles.



Zenon Char
Registered: May 15, 2008
Total Posts: 755
Country: Canada

BrianO wrote:
no_surrender wrote: I should clarify, I actually WANTED some ghosting, just not in the main subject. I was trying to create a solid subject in the foreground with the "customers" being subjected to motion blur from the slow shutter. Wondering if I should be adding a second light to help freeze the main subject. This is a whole lot harder than I thought.

You can't really freeze the main subject and blur the other people if the subject is receiving the same ambient light that's lighting the others. If so, the long shutter speed will record the subject's motion just as it does the others'.

Only if the subject is in the dark and the BG is in light can you can drag the shutter to bring up the BG exposure and use flash to light the subject without blur.


Yep. Here is an example where my flash was the dominant light source but eventually over distance the ambient light becomes stronger. So when doing this you have to keep that in mind. As long as no one is dancing to Michael Jackson tunes and doing backflips in the background and you are steady you can get away with a little movement of the people/objects behind the subject.

Shutter 1/15 and I swept the camera as I pressed the shutter. As you can see the t-shirt and card on the table are OK but the christmas tree behind has trails. This can make a unique shot at a wedding if you get it right.



Rodolfo Paiz
Registered: Jan 07, 2007
Total Posts: 9620
Country: United States

Note, too, that in that image the ISO is nowhere near 400.



Zenon Char
Registered: May 15, 2008
Total Posts: 755
Country: Canada

The shutter was actually 1/10. Sorry - been a while since I looked @ the EXIF.



cgardner
Registered: Nov 18, 2002
Total Posts: 9376
Country: United States

If there is ambient motion blur the shutter speed is too slow. If the lens is wide open already the solution to eliminate the blur is to raise the ISO. That will allow the shutter speed to be raised and eliminate the blur before you address the issues involving flash.

Let's say we are photographing a person in ambient light who is 8ft from the camera with a white wall behind them. We focus on the face, adjust aperture for the desired DOF, select a shutter speed we can hold without blur, then find the ISO speed that will produce a correctly exposed face.

Now we have correct exposure on the face and background already so why add flash?

I often add flash indoors because the steep angle of the light from overhead sources causes the brow to shade the eyes. Adding flash on a bracket gets light in the eyes and creates natural downward modeling, but it also requires adjusting exposure and reducing the brightness of the background to compensate for the added light in the foreground.

Now we turn on the flash on camera and add 1/stop of light. Shutter speed doesn't affect flash exposure because its duration is so short. To compensate for that extra stop of light on the foreground face we need to close the aperture a stop. What happens to the exposure of the wall behind in the background? It depends on how far behind the subject and flash it is because flash falls off rapidly in intensity compared to natural light.

Direct flash falls off in intensity about 2 stops with each doubling of distance. If the flash lit person is leaning on the wall the camera will record it as white because it is the same distance. If the wall is 3ft behind him (11ft from flash) it will be recorded 1-stop darker, light gray. if it is 8ft behind (16ft from flash) it will be middle gray.

If we bounce the flash off the ceiling between camera and subject or use a cap diffuser which sends most of the flash up the point of fall-off starts where the flash hits the ceiling not the flash. That lights the space more evenly with the flash so compared to a direct flash shot a wall 3 or 8 feet behind will be brighter. Not as bright at the foreground subject but not so dark it looks like he's standing at the mouth of a cave. He'll have more natural modeling on the face because the light is downward instead of eye-level.

If you want to isolate the subject on a dark background use direct flash and let the fall off make the background darker. If a more normal background is desired bouncing the flash instead will make the lighting of foreground / background more even. With either strategy the closer the foreground and background are (so they will get the same amount of flash) the closer they will be in exposure.

Often when using flash I will move people or rearrange furniture to get them closer together relative to the flash for even exposure. Standing on a chair or ladder also gets things below a more equal distance to a light on the camera. The best way I know to get even light on a scene or group with one flash is get above it on a ladder and shoot down. With groups you just have them look up at the camera and flash or bounce the flash off the ceiling over their heads.

If the ambient light as a dominant direction, like sunlight outdoors, an effective strategy to balance flash with ambient is to put the ambient source (e.g. sun) behind the subject as rim light, then lift the shadows on the front with flash.

Outdoors the sun is "Sunny 16" and the shaded sky lit side is 3-stops darker. A camera has a range of detail of about 6-8 stops of if we were to expose the sunlit parts on the backlit white shirt at 250.250.250 with detail the shaded side will fall almost in the middle of the camera's range and be recorded as gray. The face in shade will be even darker.

Let's assume the flash sync limit is 1/250. At ISO 100 an aperture of about f/8 will be needed to keep the sunny parts of the white shirt from clipping. Now we simply add flash on the front until the front side of the shirt is also just below clipping and slightly darker than the sunny backlit parts.

If using Av mode in backlight with EC=0 the metering will blow the sunny highlights but make the shaded face more or less normally exposed because the metering is center weighted and trying to make the face in the center look normally exposed. To get the small sun-lit highlights on the edges of the shirt to stop flashing in the clipping warning will require about - 2 EC. Now the sunny parts of the shirt will be exposed accurately at 250.250.250 but the face in the shaded side will not be. That's not a problem because we plan to light the face will the flash.

We turn on the flash in ETTL mode with FEC=0 and take a shot. The metering will compare ambient and the preflash and guess how much flash is needed to balance the two. If we first get the sunny highlights under clipping the guess at FEC=0 will usually be very close. If not we adjust the FEC up/down to get the front of the shirt below clipping and about 1/2 stop darker than the sunny parts, similar to how our adaptive eyes / brain perceive it in person. In other words, tweek the FEC until it looks "right" compared to the background context.


As a general rule of thumb outdoors if it's not feasible to use flash, such as shooting a ball game, I keep the sun over my shoulder and light on the subject "flat". It's not flat like flash on camera because it always comes from overhead at 45 to 60 degrees above the horizon most of the day. But it if coming over your shoulder it will create few shadows the in important areas. The camera will be able to retain detail in both white uniforms and most of the detail in dark ones when exposure is set to retain detail in the white ones.

When i can put a flash lit subject in the foreground I put the sun at the subject's back and use flash in front, raising it on a bracket to make it more natural. But there is a Catch-22. Remember we use flash in backlight because the camera sensor cannot handle the contrast of the backlight. The background is back lit also and will have the same too dark mid-tones and loss of shadow detail our subject did on the front side.

The solution? if you "normal" background detail find a location where the sun over your shoulder so the background is not cross lit and creating contrast the sensor can't handle. Then find a shady spot in the foreground out of the direct sun like a porch or doorway alcove and put your subject there lit with with flash to balance the ambient as in the backlighting scenario described above.

Those are the type decisions you need to learn to make on the fly to be effective using flash, picking the strategy that best meets the goals of the shot. Each new scene is a problem to solve and I've been using flash a long time so and found solutions for most. I've got a site full of tutorials to share them at: http://photo.nova.org




no_surrender
Registered: Apr 23, 2011
Total Posts: 1128
Country: Italy

BrianO wrote:
no_surrender wrote: I should clarify, I actually WANTED some ghosting, just not in the main subject. I was trying to create a solid subject in the foreground with the "customers" being subjected to motion blur from the slow shutter. Wondering if I should be adding a second light to help freeze the main subject. This is a whole lot harder than I thought.

You can't really freeze the main subject and blur the other people if the subject is receiving the same ambient light that's lighting the others. If so, the long shutter speed will record the subject's motion just as it does the others'.

Only if the subject is in the dark and the BG is in light can you can drag the shutter to bring up the BG exposure and use flash to light the subject without blur.


I was trying to light only the subject which I thought would have allowed me to show motion blur in the other people, but freeze the main subject. It worked for the most part, but I still ended up with some ghosting.

Kevin

Here are some of the images:

1. SOOC






2. The shot I was going for, but I'm starting not to like the composition or how brightly I brought it up to in post. Originally, I was looking to shoot with "customers" in the background which would be in motion, but we decided to use his crew of bartenders as the fill in customers.






3. On camera flash used only to trigger off camera flash to their left. Ghost city.






4. They wanted a group shot, I'm using 2 flashes here because I had WAY too much ghosting from using just one light. I had one on a stand to their left and the other off camera hand-held by me to my left. I used a small snoot (opened up as a flag) to try and prevent it from hitting the refrigerator camera left.








Rodolfo Paiz wrote:
no_surrender wrote:
Still having a terrible time properly mixing *low light* ambient and flash. Just finished a bar type scene at ISO 400 and still ended up with a >1" shutter...yeah yeah, it was at f/11 though. [...] I should clarify, I actually WANTED some ghosting, just not in the main subject. I was trying to create a solid subject in the foreground with the "customers" being subjected to motion blur from the slow shutter. Wondering if I should be adding a second light to help freeze the main subject. This is a whole lot harder than I thought.


Practicing needs to involve some exploration and experimentation, and then learning from both the failed experiments and the successful ones. It's not that hard, but you're too afraid of failure, and so you're making things harder on yourself because you're limiting your opportunities to learn.

Shove the ISO -- hard -- straight to ISO 3200 and shoot that way for at least half the session. Just do it. Then work on post-processing those images and see how they're different, how you need to treat them, and just how usable they are. Remember to print a few, don't just look at them on-screen. Noise is invariably less of a problem in print than you'd think from first looking at the file on-screen.

The higher ISO will immediately bring your SS back to around 1/8" which is much more manageable. Also, because the capture is 8x more sensitive (3200 vs 400), you'll need 1/8 as much flash power to get the same exposure. Flashes provide less power by limiting duration, which means you'll get a sharper subject since the light is on for a shorter time (at 1/8 power, something like 1/5000"). You don't necessarily need a second light.

You can also reduce ghosting on your main subject by putting as little ambient as possible on him/her and lighting him/her almost exclusively with the flash. If you have a subject in near-darkness, lit by flash, you can have a long-ish shutter speed to blur the background motion while only minimally blurring the subject. Remember to tell them to hold very still... every little bit helps.

Lastly, remember that DOF is something that you may need/want to sacrifice. I'd prefer the background not to be crisp and sharp, but just a little OOF to create a little separation from the main subject. Do some test shooting (again, deliberately trying things that may not work to learn from them) at f/11, f/8, f/5.6, and f/4, and don't worry about your subject on these. Think only of how the background looks and how blurred it is or isn't, and which "look" you like best. You may prefer f/4 (I would). Or, you may still prefer f/11 but decide that you can tolerate f/8... and right there you've just gained one full stop of light, meaning your shutter speed doubles.


Yes, I still need more practice, no mystery there!

I understand what you're saying about putting them in as little ambient as possible, but to keep them in the scene I can't exactly remove the subject from the ambient light unless I somehow placed flags everywhere to keep the ambient from reaching him/her...not exactly an option. I basically tried to limit the ambient altogether by choosing a small enough aperture to give me good DOF, but keep the place looking pretty dim, as it should.

I did ask them all to try and remain very still, but didn't want to prevent them from being themselves and giving me the genuine expressions I got.

They allowed me to come in an hour prior to opening to set up and do this before they opened the doors.

I agree with your last comment regarding DOF and the reasons why. I'm not sure if I was just flustered and settled or what, but this has definitely been a challenge for me and I'm looking forward to learn more and improve. My friend enjoyed the shots, but we've already agreed to another shoot so I can try to get a better shot.

Thanks again for your help, it is much appreciated!

Kevin


Zenon Char wrote:
BrianO wrote:
no_surrender wrote: I should clarify, I actually WANTED some ghosting, just not in the main subject. I was trying to create a solid subject in the foreground with the "customers" being subjected to motion blur from the slow shutter. Wondering if I should be adding a second light to help freeze the main subject. This is a whole lot harder than I thought.

You can't really freeze the main subject and blur the other people if the subject is receiving the same ambient light that's lighting the others. If so, the long shutter speed will record the subject's motion just as it does the others'.

Only if the subject is in the dark and the BG is in light can you can drag the shutter to bring up the BG exposure and use flash to light the subject without blur.


Yep. Here is an example where my flash was the dominant light source but eventually over distance the ambient light becomes stronger. So when doing this you have to keep that in mind. As long as no one is dancing to Michael Jackson tunes and doing backflips in the background and you are steady you can get away with a little movement of the people/objects behind the subject.

Shutter 1/15 and I swept the camera as I pressed the shutter. As you can see the t-shirt and card on the table are OK but the christmas tree behind has trails. This can make a unique shot at a wedding if you get it right.


This is pretty much what I was trying to do...using my flash as dominant light on the subject but still ended up with ghosting.

Question: How can we balance the light from the flash with ambient? In your shot, to prevent the shirt from looking "flashed?" Gels or is there a different way?

Thanks for the example! Kevin


Rodolfo Paiz wrote:
Note, too, that in that image the ISO is nowhere near 400.


Rodolfo, thanks for pointing that out...message received.


cgardner wrote:
If there is ambient motion blur the shutter speed is too slow. If the lens is wide open already the solution to eliminate the blur is to raise the ISO. That will allow the shutter speed to be raised and eliminate the blur before you address the issues involving flash.

Let's say we are photographing a person in ambient light who is 8ft from the camera with a white wall behind them. We focus on the face, adjust aperture for the desired DOF, select a shutter speed we can hold without blur, then find the ISO speed that will produce a correctly exposed face.

Now we have correct exposure on the face and background already so why add flash?

I often add flash indoors because the steep angle of the light from overhead sources causes the brow to shade the eyes. Adding flash on a bracket gets light in the eyes and creates natural downward modeling, but it also requires adjusting exposure and reducing the brightness of the background to compensate for the added light in the foreground.

Now we turn on the flash on camera and add 1/stop of light. Shutter speed doesn't affect flash exposure because its duration is so short. To compensate for that extra stop of light on the foreground face we need to close the aperture a stop. What happens to the exposure of the wall behind in the background? It depends on how far behind the subject and flash it is because flash falls off rapidly in intensity compared to natural light.

Direct flash falls off in intensity about 2 stops with each doubling of distance. If the flash lit person is leaning on the wall the camera will record it as white because it is the same distance. If the wall is 3ft behind him (11ft from flash) it will be recorded 1-stop darker, light gray. if it is 8ft behind (16ft from flash) it will be middle gray.

If we bounce the flash off the ceiling between camera and subject or use a cap diffuser which sends most of the flash up the point of fall-off starts where the flash hits the ceiling not the flash. That lights the space more evenly with the flash so compared to a direct flash shot a wall 3 or 8 feet behind will be brighter. Not as bright at the foreground subject but not so dark it looks like he's standing at the mouth of a cave. He'll have more natural modeling on the face because the light is downward instead of eye-level.

If you want to isolate the subject on a dark background use direct flash and let the fall off make the background darker. If a more normal background is desired bouncing the flash instead will make the lighting of foreground / background more even. With either strategy the closer the foreground and background are (so they will get the same amount of flash) the closer they will be in exposure.

Often when using flash I will move people or rearrange furniture to get them closer together relative to the flash for even exposure. Standing on a chair or ladder also gets things below a more equal distance to a light on the camera. The best way I know to get even light on a scene or group with one flash is get above it on a ladder and shoot down. With groups you just have them look up at the camera and flash or bounce the flash off the ceiling over their heads.

If the ambient light as a dominant direction, like sunlight outdoors, an effective strategy to balance flash with ambient is to put the ambient source (e.g. sun) behind the subject as rim light, then lift the shadows on the front with flash.

Outdoors the sun is "Sunny 16" and the shaded sky lit side is 3-stops darker. A camera has a range of detail of about 6-8 stops of if we were to expose the sunlit parts on the backlit white shirt at 250.250.250 with detail the shaded side will fall almost in the middle of the camera's range and be recorded as gray. The face in shade will be even darker.

Let's assume the flash sync limit is 1/250. At ISO 100 an aperture of about f/8 will be needed to keep the sunny parts of the white shirt from clipping. Now we simply add flash on the front until the front side of the shirt is also just below clipping and slightly darker than the sunny backlit parts.

If using Av mode in backlight with EC=0 the metering will blow the sunny highlights but make the shaded face more or less normally exposed because the metering is center weighted and trying to make the face in the center look normally exposed. To get the small sun-lit highlights on the edges of the shirt to stop flashing in the clipping warning will require about - 2 EC. Now the sunny parts of the shirt will be exposed accurately at 250.250.250 but the face in the shaded side will not be. That's not a problem because we plan to light the face will the flash.

We turn on the flash in ETTL mode with FEC=0 and take a shot. The metering will compare ambient and the preflash and guess how much flash is needed to balance the two. If we first get the sunny highlights under clipping the guess at FEC=0 will usually be very close. If not we adjust the FEC up/down to get the front of the shirt below clipping and about 1/2 stop darker than the sunny parts, similar to how our adaptive eyes / brain perceive it in person. In other words, tweek the FEC until it looks "right" compared to the background context.


As a general rule of thumb outdoors if it's not feasible to use flash, such as shooting a ball game, I keep the sun over my shoulder and light on the subject "flat". It's not flat like flash on camera because it always comes from overhead at 45 to 60 degrees above the horizon most of the day. But it if coming over your shoulder it will create few shadows the in important areas. The camera will be able to retain detail in both white uniforms and most of the detail in dark ones when exposure is set to retain detail in the white ones.

When i can put a flash lit subject in the foreground I put the sun at the subject's back and use flash in front, raising it on a bracket to make it more natural. But there is a Catch-22. Remember we use flash in backlight because the camera sensor cannot handle the contrast of the backlight. The background is back lit also and will have the same too dark mid-tones and loss of shadow detail our subject did on the front side.

The solution? if you "normal" background detail find a location where the sun over your shoulder so the background is not cross lit and creating contrast the sensor can't handle. Then find a shady spot in the foreground out of the direct sun like a porch or doorway alcove and put your subject there lit with with flash to balance the ambient as in the backlighting scenario described above.

Those are the type decisions you need to learn to make on the fly to be effective using flash, picking the strategy that best meets the goals of the shot. Each new scene is a problem to solve and I've been using flash a long time so and found solutions for most. I've got a site full of tutorials to share them at: http://photo.nova.org



Chuck, WELCOME BACK!

Thank you, once again, for taking the time to explain so much more than I've asked for. Your suggestions are always welcome! I've read many articles on your site, but don't remember seeing any that pertain to this particular type of lighting condition: low light indoors requiring balanced flash to isolate a subject or group of subjects.

I'm going to have to re-read your post here before I head out for another natural light type shoot. Thanks again!

Kevin


Rodolfo Paiz
Registered: Jan 07, 2007
Total Posts: 9620
Country: United States

Question: How can we balance the light from the flash with ambient? In your shot, to prevent the shirt from looking "flashed?" Gels or is there a different way?

Gels are the simplest and the least time-consuming. Masking/selecting the subject and post-processing the white balance separately for the subject and background is another... it just takes waaaaay too long for my taste and is very little fun. Always shoot RAW, if only for the flexibility to change and tweak WB that JPG will never give you.

Some other thoughts, looking mostly at the last shot:

1. That background looks pretty bright. You could try using 2x the shutter speed to get the background a stop darker, and change your flash power to maintain your chosen brightness level on your main subjects.

2. Your main flash to their left (I believe it's called the "key" light as being the main one) might be better placed a little above them, and about 45 degrees to their front/left rather than directly beside them. The side lighting is very strong.

3. I'd also suggest turning down the power on the key flash to their left, and turning up the power on the flash you're holding to your left (the "fill" light) to even out the brightness a little. You still want one to be a little stronger than the other, but you don't want the contrast to be so strong.

4. In shot #2, you might want to place the light a little higher up to provide more of a "spotlight" effect. But though you may not like the comp, and I agree the background is too bright, the overall shot works.

5. Shot #4, and #2 especially, are not far from a successful shot from a lighting perspective... just need to fine-tune your camera settings, flash power and placement, and so on.



curious80
Registered: Jun 18, 2010
Total Posts: 1137
Country: United States

no_surrender wrote:
Still having a terrible time properly mixing *low light* ambient and flash. Just finished a bar type scene at ISO 400 and still ended up with a >1" shutter...yeah yeah, it was at f/11 though. I wanted a nice deep dof to capture the environment, but still ended up with more ghosting than I would have liked.

I should clarify, I actually WANTED some ghosting, just not in the main subject. I was trying to create a solid subject in the foreground with the "customers" being subjected to motion blur from the slow shutter. Wondering if I should be adding a second light to help freeze the main subject. This is a whole lot harder than I thought.

I know I could have bumped my ISO quite a bit more, but am still pretty hesitant to do that. Just need to keep practicing.

Kevin


First please let go of your fear of high ISOs. Keep in mind that any given ISO the noise in bright parts is much less than the noise in dark parts. The parts of your image exposed with flash would be fairly noiseless even at ISO 3200. I had no hesitation in using my much older APS-C 30D at ISO 800 with flash and ISO 1600 was also very fine. You are using a 5DII which is much cleaner so at the very least try going up to ISO 1600 as a first step until you are comfortable enough to try ISO 3200.

Second, you might be overdoing the stopping down for DOF. You are just in a smallish room, not shooting a landscape where you need everything in focus till infinity. Going down to f/8 might still give you the needed DOF as long as you are not focusing very close. Also DOF extends both ways from the plane of focus - about 1/3rd of it is in front of the point of focus and 2/3rd is behind the focus. So instead of using f/11 and focus on the main subject in front you can get similar overall results by shooting at f/8 and focusing a little bit behind the main subject.

Third, if you can move the flash farther away from the subject then the ratio of the amount of light that gets to the main subject versus the amount of light that gets to the background will become smaller and you will not need as long a exposure for background as you need right now (though you will overall need more flash power - something that will be helped by the two points above).

I would strongly suggest that before going on your next session, spend time at your home playing with various ISOs and apertures to develop a good feel for what is acceptable in terms of ISO noise and DOF.



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