Thursday, October 8, 2009

QnA: Big Group in a Big, Dark Room

Laaaate Wednesday night, Strobist reader Vicki Madden asked, via Twitter:

"Need advice on big job on Friday -- large group in high school gym?"
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First of all, not even 48 hours before a "big job" is not the best time to be asking for vague advice. And using @Strobist on Twitter probably is not the best venue. (Try the Strobist Flickr group for that kind of urgent stuff.)

But the question happens to set up a good exercise in pre-thinking your lighting for a scary environment -- not to mention getting into the psychology of doing a large group shot. So even though it is short notice, what the hey.

(Also, my "On Assignment" previously slated for today had to be pushed back. Which always makes a reader lighting question way more appealing to me.)

So, Vicki, hit the jump for a detailed walk-thru on how to approach your shoot, with a minimum of gear.
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First Things First

The minimum lighting setup I would use for this would be three bare speedlights and stands. So I sent Vicki a direct message via Twitter yesterday morning to make sure she could scrounge at least that -- and that there was a full walk-thru was coming on Strobist at 12:00am eastern time.

Here are my assumptions:

One, that she can get ahold of three off-camera sync-able speedlights. Two, that the gym is scary dark, just to make things interesting. Three, that she can scrounge one helper onsite for some help pre-setting the light. And four, let's assume 60 people in the group.


The Gym is Big and The Gym is Dark

And that's the good news.

No, seriously, that is good news. Because with a big group, you're gonna need some distance to light them evenly. And you want dark, too. If this were being done outdoors in the full sun, you'd have no hope of competing with that light level with a few speedlights at any distance. (As in, beyond six feet or so.)

So the dark is working for you, too.

More good news from the gym: Built-in elevation for both you and your lights. Call ahead to make sure the bleachers will be set up for the group shot -- on both sides. Don't leave it to chance, and don't ask meekly, either. (Asking meekly is tantamount to leaving it to chance.)

Call up and say something to the effect of, "Hi, this is Vicki Madden. I am going to be doing the group shot of (whatever) in the gym on Friday, and I need to make sure that both sets of bleachers will be extended at least an hour before the shoot, so we can set up the lighting. Thanks very much."

Call the office, and sound like you make this call every day. The person who answers the phone will not be the person who takes care of the bleachers. But your urgency and authority will be conveyed in their message to the person who will get your bleachers opened up.

And still, arrive a little more than an hour before, and expect to find the bleachers closed. Just expect it and it will not be a stressor when it happens. Track down the gym guy and explain that these are supposed to be open within a few minutes, just to make sure he is on track for your setup time.


Setting Up

You'll be shooting from halfway up one of the sets of bleachers. (The home set, if an emblem is coming into play on the floor.) You'll be halfway up to get some elevation, and to leave some space above your vantage point for your key light.

So, imagine your group in front of you. Place your helper at dead center of what will be the middle of, say, three rows of people fairly tightly packed on the gym floor. Estimate your group and figure out the lens you'll need now, from your shooting position.


Place Your Key

Let's say for the sake of argument, that you are going to key light from over your left shoulder. Set your flash well above you (maybe at the top row if in a high school) in the bleachers. Actually, use the foot rest for the people that would be sitting in the top row. Close the light stand, slide it down in there and open it up, wedged in the foot area. Nice and sturdy.

Set your speedlight on 1/2 power, and zoom it to a telephoto setting -- say, 85mm or 105mm. (The 200mm setting on an SB-900, if you are so blessed, might be a bit tight.) Aim it a few feet over the head of the helper in the dead center of your future group. You are doing this not because of poor aim, you are doing it to evenly feather the light left to right, front to back.

Set your camera to a relatively high shutter speed, say at 1/125th or 1/250th. I am assuming you have crappy weird gym light and that we are doing this all with flash. Let the gym go dark or darkish on the ambient.

You should get about f/2.8 or f/4 on your center group guy. If you cannot get that, raise your ISO to 800 if your camera makes really good files at that ISO. Otherwise, go to full power on your speedlight. (The former is preferable, as it buys you a faster recycle time so you can get more frames shot before wearing out the group's attention span.)

If you have enough light coming from your speedlight, go to f/5.6 and buy yourself some depth of field. Don't believe your speedlight is capable of that? You might be surprised.

Obviously, if you are using monoblocs in this setting, you'll have power and aperture to burn.

Test your key light for a good exposure on your group area in three different places: Dead center, back row furthest away from the key, and front row closest to the key. Since your flash is on a tele setting, you have real control over your beam of light. By firing it over the front row's heads and a little towards the right side of the back row, there will be an angle that give you nice, even exposures all over your group area.

This is called feathering the light, and it is a good way to light large areas evenly. This is because the near areas fall at the edge of the light's beam. So they receive less light, which compensates for the fact that they are closer. Plus, it will light the gym floor around your subjects, feathering it darker as it gets closer to camera the camera position.

Congratulations, your key light is now set.


Place your Separation light

Now, we are going to the bleachers on the other side, caddy corner, up top. We are going to repeat the exact process to create a light that will separate everyone from the dark background, and light up the gym floor in areas missed by the key light.

(Note: Your remotes will have to be able to reach across a gym. If not, you'll need to slave your lights to each other. This should be very easy and effective, as they are essentially pointed right at each other.)

Aim this light over the heads just like the key, and test your exposures while you are at the light. Use that tele zoom setting and there will be an angle that places the entire group at roughly the same exposure. You might want to gobo the front of that light to where it can see your whole group, but not your camera. This will kill any flare from that light coming into your lens.


Now, the Fill

So, that was easy. Now you have hard crosslight evenly lighting your large group. But there are gonna be wicked shadows because we are not taking the mystery vapor ambient into account. We'll fix that with on-axis flash.

This light, like both of your others, is gonna be bare. Why? Because unless you have a 15-foot parabolic reflector, you are not going to do anything with a light softener at this distance other than rob yourself of light intensity. So we are going for hard, efficient and crisp. Those hard shadows created by the key and separation light will be just fine if we can keep them from falling too far.

So get in your eventual shooting position, center bleachers and half-way up. We will place your helper guy in the center again, and dial in your fill light so his shadows look good -- probably about 1.5 stops down or so. No need to get technical -- just do it until he looks good.

You will need to adjust your flash beam to match your lens, so you will get full coverage on your group. Also, feather this light up a little bit, to make for an even fill exposure front-to-back. Makes sense now, huh?

You are closer than the key at your shooting position, so I would expect that 1/8 or 1/4 power might do the trick. Start there and adjust your power level by eye until it looks right. The shadows should look like natural, legible shadows instead of black holes. It's like cooking -- add salt to taste.

Place your fill light on the opposite side of your lens axis as is your key light. For us, that would mean just to the right of your camera lens -- in very close. This way you will get no double shadows, as the key will erase the fill shadows nicely. And the fill will see everything that you can see which would be in the shadow of the key light.

Now, walk your light helper around the group area and test middle, front right, front left, back right, etc. Admire your handiwork.


Your Light is Set. Now What?

Now the group. For our 60 people, I would divide them into three or four rows. Make each row have one more person than the row in front, to make a nice fan and to be able to stagger people. For example, instead of three rows of 20, you'd go 19, 20 and 21.

Before everyone gets there, know who the most important person (or people) is in the group. They go front and center. Or mid-center if they are very tall. Before you shoot, introduce yourself to the Big Cheese and explain that you will probably have a little fun at their expense to keep the group relaxed and engaged. It works.

You are now officially the emcee of a three-ring circus. Work fast and keep people loose. Bring them in and concentrate on four things, quickly:


1. Arrange by height -- short in front row, tall in back. Help people divide themselves by saying something like, "Everyone 5'6" and under in the front row, everyone 5'10 and over to the back row." Adjust as needed for your own numbers as mentioned above.

2. Everyone with glasses goes on the side of your group from which you are using your key light. In our case, camera left.

3. Now, have everyone turn their bodies in toward center on both sides. This not only looks better than straight on, but will naturally kill your key and fill reflections in peoples' glasses on the left-hand side. (Even the fill should miss the glasses, as people will naturally face a little away from the key and fill while turning toward center. It works.)

4. Ask everyone to make sure they can see your key light (tell them which light that is) so everyone will have a lit face. If you can see them, they can also see your on-axis fill. No modeling lights needed. Pop a quick test frame and very quickly check to make sure there is not a major problem. Now is not the time to find a problem. You had testing time for that.


Shoot Fast

Focus on the center of the group, about a third of the way in. That'll maximize your minimal depth of field. At this working distance you should be fine. But keep the group tightly packed, just to help yourself out.

Keep the group engaged at the expense of the Big Cheese. If you are comfy enough to joke with/about that person, the group will be a lot more relaxed and loose. I once told a VP at Northrup Grumman who was surrounded by his subordinates that it was great to see him back in men's clothing. (That's why you give them a heads-up first.)

Give them notice as to when you are going to shoot. As in One, Two, Three (pop). But jump the gun occasionally to miss the anticipatory blinkers. As in, One, Two, (pop) Three. Some people just plan to blink for flashes. Beat them to the punch.

Work fast, mind your recycle time (which you tested) and shoot at least a couple dozen frames. Crack jokes the whole time. Be ready to jump on any reaction with a frame. Don't warn them that this is a last frame. Warn them that "We only have about 30 minutes of this left," and shoot when they react. They will.

Use a big, booming authoritative voice (like in Bert Stephani's excellent group shot example) and be in control the entire time. They need you to do that. Get in, get out fast and have fun.

Good luck, Vicki.


Have a Question?

Shoot it to me in a comment on this post. I will pick the best ones and try to answer them in a future Q&A.

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