Lighting a group of 10-12 - Will one strobe be sufficient?

I've done a lot of group shots of different sizes, but I can't decide if I can get away with one strobe for this. I'll probably put 5 or 6 people in the front and 5 or 6 in the back row. I was thinking of just using one strobe with a 60" reflective umbrella to throw a swath of light at the group from directly above me to keep it simple. It'll be indoors, and I'll probably underexpose the background by 1-2 stops. I measured out an area in my home studio that looked about right for a group this size and did some experiments, but it's just hard to tell without actual people standing there, and I didn't have a dozen of my closest friends around for the experiment. Let me know if you've done this and how well it worked. Thanks.

I have done a large group with a 60" umbrella and working off the inverse square law it can be done just fine. The shadows will be a little harder.

It's likely we won't care much about the background. So as long as I get good (and even) coverage on the people with the lighting, that's all that matters. I could also use the 53" Elinchrom octa or even the 74" indirect octa, although I'm not sure there's room for the really big octa. I could also do 2 strobes, if necessary. I need to have 2-3 different setups at the same time for this corporate gig, and I'm trying to keep it simple and just bring what I need.

You'll most likely be out shooting a speedlite trying to pull a decent aperture to keep everyone in focus. You can bump the ISO and play a waiting game while the speedlite recharges.

Is the venue one where you could bounce off the ceiling effectively? If the ceiling is a light, white or nearly white color and you are using a strobe, not a speedlight, you should be able to light it well.

Why not two flashguns firing into the umbrella?

I used a Metz AF 58-2 and a 430EX II with a 45" shoot-through brolly for this one:

With a single strobe some falloff from center to edge is inevitable. You would get more even light by having two strobes to give a broader field of even light. since you are underexposing the ambient the falloff will be more noticeable than if the flash were balanced fill.

Alveric: What a difference! Only mother nature (White reflective snow field) was very friendly or am I wrong?

It is amazing what a little flash can to to improve a group shot.

10 people is relatively easy.

One speedlite will work unless you have to get way away and the ambient is high.

I routinely use one or two speedlites for groups up to 20 in churches and reception venues.

samsen wrote in post #16845073
Alveric: What a difference! Only mother nature (White reflective snow field) was very friendly or am I wrong?

Nope, you're not. Know you that up until you brought it up I hadn't even noticed? I'm blessed I always get Providential help in my shoots.

I also forgot to give the settings: 24mm, 1/320 @ f/11, ISO 320. I'da gotten more punch from the flashguns had I not been using HSS, but shooting @ 1/200 woulda blown out the sky, I think. In a venue, I'm betting HSS is not needed: point in fact, you might want to drag the shutter, so one speedlite would do it.

Regarding the venue, I've done shoots for this company before and know the layout of the place. So I'm pretty sure where they're going to want to do the group shot. It's a lab area with white walls and ceiling, and the ceiling is really high. I recently purchased the Profoto B1 and have been looking for an excuse to use it. I'll be set up in another room to do headshots with 2-3 strobes, and I thought I might use the B1 with a 60" Softlighter II for the group shot (and I was thinking no diffuser - just use it as a reflective umbrella). I have TTL with the B1 and can play around with camera settings to balance the ambient. My only concern is even coverage. I want to send out a swath of light that gives me pretty even coverage from end to end of this relatively small group. The B1 has probably 10 times the power of a speedlite. So with the right modifier, I would think I should be able to do this.

Blast that strobe into a white wall behind you? Giant modifier.

Maybe a scrim between the brolly and the group can be used to enlarge the light source? A 4x6 scrim would do nicely, methinks.

Alveric wrote in post #16846903
Maybe a scrim between the brolly and the group can be used to enlarge the light source? A 4x6 scrim would do nicely, methinks.

That sounds like a great idea. Is it best to rent scrims this size?

Fire the B1 into the wall behind you and maybe a bit left or right.
With that power, a reasonable aperture will get all the face sharp.

I was think ing you were going to have to find a way to do this with a couple of speedlites.

The B1 makes it kind of a no brainer.

Just a reminder, the clients isn't interesting is creative, artsy lighting. They want everyone sharp, no shadows and smiling.
This is basic editorial photography not a fine arts project.