Sheffield Wedding photobooth outside at night! (How to)

Weddings are challenging at the best of times, when I was tasked with setting up a Photobooth that captured a warm atmosphere of forest wedding during a reception I thought that sounds completely fine. Of course then it turns out to be in the middle of a wood, at 9pm, in Winter...
It was pitch black, to the eye you couldn't see a thing just outside of the main reception tent. Still I thought, photographers are nothing if not problem solvers, so I went on to set up a section of the forest so I can get consistent, quality photos, that still capture the atmosphere. Here's a slideshow of some of the photos of guests, followed by a detailed (and a bit technical) breakdown of how I setup this night time, outdoor Photo Booth!

I wanted the photos to have a sense of warmth: summery, firey, orangey glow. Handily there was a sodium street lamp in the far distance, so I positioned it in the background of the shot and set my exposure to get a nice orange glow from it. Now this means 'dragging the shutter' and when you are going to have moving subjects you have to be careful, its a tradeoff of absorbing ambient light, and ghosting everyone in the shot, so I went as slow as 0.5sec, about the slowest speed I could get away with. I could get lots of light in if I opened up my lenses aperture more, but as I knew crowds of merry guests would be getting in front of the lens soon, I needed a decent depth of field. f/5.0 at 85mm was enough to get a good depth of subjects in focus and still soften the far background. Okay sorted then? Not quite, at base ISO the shot was pitch black again because of the aperture! So it had to go up, this is where having a modern full frame sensor helps, I took my Nikon D750 up to ISO 4000 with very little noise of image degradation. After all that faffing, the image looks like this:

Yes that's my silly face in the photo, not that you can see it yet!

All that work and we still can't see anything, typical. Well now we have the ambient light nice and atmospheric, it's time to start adding flash. You should always start with ambient, then add your lights one by one, I see photographers throwing 10 flash in at once then trying to control them, don't be that loser.
First is the key light, in this case as there is going to be lots of people across the frame I need a big, soft light source. I went for a 7 foot Parabolic umbrella with a  diffusion sock over the front, this basically turns it into a massive softbox. It would be an engineering marvel to get that thing above the subjects, so it's off too the side. Here's the same shot again with the key light added:

Waheyy, now you can see some dopey human wandering around

In a studio you would normally have two lights like this, one on each side at about 45 deg to the subjects, this lets you get nice even lighting across a group, however due to the nature of this Photobooth, there are going to be guests queuing along the left of camera, and fishing around in a props bin. There's a common problem you get when lighting a group with one key light like I did here, and thats the light dying off before it reaches the subjects furthest from the light (to the left of frame in this case). My favourite way to get around this comes back to my background in physics (I can smell your tears of joy from here but bare with me). Basically, the more surface area of the light source a subjects is exposed to the more light will hit them. So you want the subject that is furthest from the light to get the most surface area, and the subject closest to only get a little sliver of the surface area. So, point the light source to the far left of frame! There is some faffing to do to get it perfect, just stand in the frame like I am and look at your light, as you move around you can see that the surface you are exposed to changes as you move around.

The photo above isn't bad by any means, but it doesn't have enough drama or edge for my taste, so I added a kicker light, this is an off camera flash that hits the subjects from the shadow side with a hard edge, to carve out the shape of the face. Look at the difference on the shadow side of my face down below:

Posing for myself is never awkward, not at at all :/

Better right? Having a face that goes from soft light, to soft shadow, and to hard edge light is a very fashion portrait light, I love how it shows texture of the face while staying flattering. One last thing, I said earlier that we wanted to have a sense of the forest going on, so I wanted to add one final light to illuminate just a few background branches, and fill in a few shadows a little by bouncing light around the tree canopy. The green tones it picks up really help contrast with the skin tones of the subjects and orange of the far background. All of this adds depth, and dimension.

Finishing a setup is always a happy moment!

This was a three light setup, here's a wider shot from the same camera perspective (without me this time though)

Sorry about the van and little Hyundai poking into this frame, don't blame me, I drive an alfa, and it's parked somewhere with way more tarmac!

The kicker, and background lights are bare speed lights triggered with Pocketwizards, The other beauty of using a high ISO to absorb the background light is I barely need any flash power, so that massive 7 foot parabolic only has a little SB-910 speed light in it, on quarter power at that!

If you've made it this far you deserve to know the setting and equipment I like to use for setups like this, so enjoy:
Nikon D750 + Nikkor 85mm f/1.8. Shot at 0.5sec, f/5.0, ISO 4000.
Key light: Speedlight 1/4 power, in 7foot diffused parabolic.
Kicker light: Speedlight 1/128 power, bare, zoomed tight, aimed at subjects from rear 3/4
Background light: Speedlight 1/32 power, bare, zoomed wide, aimed back towards the trees

Much love, Chris