Wednesday, September 14, 2011

Massive Group Photo

The Westlake High School Chorale - 2010
I recently shot the group portraits for the choirs at Westlake High School in Austin Texas. The shot to the left is of the 130 member Chorale. Given the size of the group and that I could only move so far back on the stage, it was a bit tricky to create this image, so I thought I'd pass on a few of the things I did to pull it off.

First, to light a group this size requires more power than the small flashes I normally use for on-location portrait photography. This job called for studio strobes, so I rented a set of 2400 watt-second Profoto Acutes from Precision Camera. Those puppies gave me enough power to light the whole stage at an aperature of f/8. At f/8, all of the people in the group, both front and back, were in focus, which was one of my primary concerns when shooting a group of this size. I decided to use only two of the three flash heads, one on each side of the camera. I shot both heads through white umbrellas to soften the light, and I put both flashes on stands and raised them to about 10 feet to make sure everyone would be illuminated.

Second, I "feathered" the lights, meaning I aimed the light on camera right at the choir members on camera left, and the one on camera left at the members on camera right. Why? Because it helps ensure the exposure is the same (or nearly so) for the people in the front row vs. the people in the back. It's a physics thing, but trust me, it works.

Third, I had hoped to get everyone into a single shot using a wide angle lens, but even the 10-20mm lens I was using couldn't cover the whole group, so I had to shoot it as five overlaping photos that I stitched together using a free application called Hugin Panorama Photo Stitcher. It's the best panorama software I've ever used and it did a great job on this photo.

Fourth, I positioned the camera near the center of the simi-circle of chior members. That kept everone at basically the same distance from the camera as I panned around to take the five shots. That explains why, in the final image, the members appear to have been in a straight line.

I had a few problems that I hope you can avoid:

First, the light from the strobes leaked around the umbrellas and created bright areas on the edges of the photo, so be careful when setting up your lights.

Second, I had some lens flare in the edge photos even though I was using a lens hood. Again, be careful setting up your lights. Make sure they're far enough back that your lens won't "see" them when you're taking the shots at either end of the panorama.

Third, each shot had a slightly different color balance and contrast, so I spent guite a bit of time in Lightroom adjusting the photos to better match each other. I'm not sure how to prevent that.

I used Photoshop to touch up the final image, which included a final white balance adjustment, extending the warped panorama image to the edges of the frame, and touching up spots and lines on the stage and background. Overall it took about two hours to create the final image.

Happy shooting!

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