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blow out a white background


glenn_s

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I read on this forum that I should overexpose a white background by about two

stops to get the classic white background.

 

I tried it and had two problems. First, light reflected off the background

onto the side of the subject's face, causing it to be overexposed.

 

Secondly, the background was not evenly exposed - the light dropped off from

left to right.

 

I'm using an AB400 and an AB800. For the main light, I used an umbrella 45

degrees to the subject's right. I put the background light just out of the

field of view to the subject's right and just slightly behind the subject.

Subject was ~4' from the wall. Background light was reflector only (no

umbrella) and positioned so that none of the light would directly hit the

subject.

 

Any thoughts about where I should place the background light to achieve even

overexposure on the background without spilling onto the subject?

 

Thanks,

Glenn

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You need to illuminate the background as evenly as possible - if you can't illuminate it evenly (difficult with a single light) then you need to overexpose the darkest part of it by around 2 stops, which adds to the problem of bounced light.

 

And, because light bounces from the background towards the subject, you need the subject to be as far from the background as possible, so that the relected light loses as much of its power as possible before reaching the subject

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Okay let's try to get you an even background that is a hot white. Tough to do with one

head, and even tougher if you don't have much space. There are a few ways to do it with

one head. The first way requires more width and the second requires more height. First

off light falls off faster the closer that you are to the source, so you need to get the source

as far away as you can from the white so that it will be more even once it reaches the

white. Putting an umbrella on your strobe will also help you to spread out your light, but

will then reqire more power. Take it out on about a 30 - 40 degree angle and meter

across the span you are trying to make white untill you get it as even as you can and then

adjust your strobe to give you the desired F-Stop. Probably going to be really hard to do

with the strobes you have as you will most likley not be able to throw enough light at your

white. You will then need to flag that light off of your subject so that you don't get any

spill hitting them. The other way wich requires more height is to put an umbrella on your

strobe and take it up high so that it rakes your white at about a 30 - 40 degree angle. The

higher you take it, the more even it get's. Again you will have to place a cutter or flag in

place to keep the spill off of your subject, unless you like the way it is hitting the hair and

giving you a little bit of rim light.

 

The bounce issue has to do with the distance that your subject is off of the white. You

can take your meter and measure the amount of bouce by standing at your subjects

position and pointing it at the white when you fire your strobes, Move untill you like what

your meter is tellign you. When you say that the bounce is making the side of your

subjects face blown out it is making me think that you are actually gettign spill from your

strobe and not from the backgound. The background bounces right back at the lens so

the top of the shoulders and rim of the ears and hair start to see it before the side of the

face. So flag your strobe off from the subject and see if that fixes your problem. (I know

you said it was positiond where none of the light would directly hit the subject, but you

didn't say that it was blocked off completly from the subject.

 

Don't set your sights to high with the limitations you have. Make it look the best you can

with what you have. Don't get discouraged when you look at photos in mags and see a

large group of environmentalists in Vanity Fair on hot white or George Clooney in Esquire

on hot white and think, "Man my stuff looks nothing like that." Large budgets, lots of

lights, and a huge studio space are a HUGE help. :) Just to give you an idea here is a gear

list that I usually order when I am doing a basic hot white for sombody ina studi.

 

6 Profoto 7a 2400 packs

6 ProHeads

6 White Profoto umbrellas

2 C-Stands

4 Cardalinis

4 V-Flats

2 Pocket Wizard receivers

4 Phono to phono cords

 

That is just for the backgound lights if I am lighting a cyclorama. Post up a sample so we

can see what is going on.

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I use 2 strobes, White Lightning 800's, on the background. Assuming a 9ft wide paper background, I put one strobe on each side, just off the paper, and about 2 1/2ft from the background. They're angled so each strobe just lights the opposite edge of the BG. I use barndoors to keep light from spilling on the subject. The subject is about 2ft in front of the BG lights. BG lights are at full power, lighting on the subject is 1/2 power or less. I've had no problem with reflections onto the subject doing this.
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Thank you all for the quick and detailed responses.

 

I'll try the umbrella on the background and moving the subject further out.

 

This is one of the pictures where the side of the face is over-exposed. (He would only pose if I let him hold the drill).

 

Thanks,

Glenn<div>00JXCc-34444184.jpg.e6f1dcbc4667cd27ab12747e4296f6db.jpg</div>

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You don't need two stops - the key is to evenly light the background. This is very difficult with less than two lights on it, however.

 

I wrote a blog post about one way to light a white background here:

 

http://www.gregrphoto.com/blog/2007/01/shooting-with-white-background.html

 

Also, the brighter your background lights with respect to the subject, the more spill you're going to get on the edges of your subject. One thing you can do is move your subject further away from the background - 4' is pretty close. Do you have room to double that?

 

Greg

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That light on the face is spill from your background strobe and is overexposed because it is combining with your key. Flag the background light off of your subject. Basically all you have to do is put something in the way of the strobe between the subject and the strobe. Make sure that is you stand at the background you can see the strobe, but if you are standing where the subject is you want to make sure you can't see ANY of that strobe. Let me look thru my on-set roids and see if I have an example for you.
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  • 3 years later...

<p>2 stops is 1.3 stops too many ... you'll have bleed coming around edges and through hair. <br>

One photographer blog says to measure the light bouncing off the back of the wall at the position of the model. If it is 1/3 stop over aperture, it is enough.</p>

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<p>Interestingly i was watching a video by Robert Seale today and about half way through it he explains exactly how to expose for a white background without spilling over to the main subject and creating fringing problems (he claims btw that overexposing the background by 0.7 f stop with digital is sufficient compared to the 1 or 2 f stop with film). Here is the link to the video. Well worth watching.<br>

<a href="http://blog.photoshelter.com/2010/04/lighting-it-up-in-austin-with-robert-seale-1.html">http://blog.photoshelter.com/2010/04/lighting-it-up-in-austin-with-robert-seale-1.html</a></p>

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<p>J'ai impression qu'on se connait Michel?<br>

Here are my comments that I posted on another forum regarding that video.<br>

----- 2010.04.09 on Dyxum<br>

I watched it and while I appreciated it I really feel that such presentations lack essential information for people learning to light. <br />I "got it", but someone new to studio lighting would be left with more questions than answers. <br /> <br />I've looked at several such videos (always on the look for good ideas to steal - and I do learn the odd tidbit) but they all lack a good structure. The main failing here, I think, is that great photogs are not necessarily great teacher/presenters. <br /> <br />Strong points <br />-mixed lighting considerations (ambient + flash or flash + flash and exposing bg and subject differently giving more creative latitude) <br />-location choice <br />-use of scrim, light "focusing", beauty dish, softbox. (Not elaborated enough - see 'goof' below.) <br />-he endorsed the idea that he was "over equipped" for the shoot and could have achieved the same with less - even a few speedlights. <br />-admitted that some shoots (inc. this one) were "structure on the fly/decision on the fly/exposure on the fly" and not always planned to the t. <br /> <br />Weak points <br />-Far too long a video (could have taken 20-30 minutes for the content given - or could have been as long with more useful content). <br />-Poor graphic presentation (detail was not visible, or hardly so) <br />-equipment lists were not in sync with the shots <br />-Too "static" a presentation <br />-Did not show metering actively - this is something beginners need more of (I think. I really learned the essential truths of metering for studio when a pro came to do some corporate shots at work. In 3 minutes I learned more about metering than in any other form). <br /> <br />Goofs:<br>

-Using a sock over a grid (though he admits to this folly at the end).<br /> -a "caller" asked what "specular" meant. His explanation was wrong. Way.</p>

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<p>Hi Alan je ne sais pas si on se connait, mais votre nom m'est familier. <br>

I did not post this link because i thought it was a brilliant educational video, i don't think it is, but it did address the question of the OP about mid way through, and being an avid enthusiast, i like watching anything about photography. I always find something new and interesting every time. </p>

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