Friday, March 23, 2007

Lighting for On the Rocks

This is the first post in my Making Of series.

On the Rocks along with Cheesy Horror, my two recent submissions to Digital Grin challenges are far and away the two most elaborate lighting setups I have done to date. The basic inspiration the lighting I used in On the Rocks came from Light: Science and Magic, Second Edition: An Introduction to Photographic Lighting by Fil Hunter and Paul Fuqua. However their description of how to achieve this light involves a large soft box. Given that my gear is currently limited to 2 shoe mount flashes (a 430EX and a 580EX) I had to find another way.

Beyond that, I had a particularly ambitious goal for this shot--to have the entire background black including the surface the glass was sitting on. Many people who take shots like this go for a black acrylic surface which is reflective. The reflective surface has a number of advantages over flat black when it comes to light control. I decided to start with flat black and fall back to acrylic if I couldn't a achieve my goal. Of course that distinction ended up irrelevant in my submitted photo, but you can see it some of the draft shots I took.

Aside from the flat black problem I had to solve, there was another issue I needed solve. The method described in Light: Science and Magic involves pointing the soft box directly at the camera. My early experiments showed that this causes enough lens flare to be obvious over a black backdrop so quickly their simple setup starts getting complicated with gobos when you start working on the details. After little playing with setups and some non-linear thinking I came up with this solution.

Here is the setup: two sheets of white/black foam core on each side of the glass (clamped to the top of my table saw) with a backdrop of black felt down the middle. The foam core sheet serve double duty. The white on the interior serves as a bounce surface for the flashes--each one acts like a small soft box lighting the glass from the side. Second, black side of the foam core acts as a gobo blocking the direct light from the flash hitting either the lens or the glass.

So, lets get this straight. The light from the flash on the left bounces off the white foam core on the right before it gets to the cup (and vice versa). The foam core on the right blocks the direct light from the flash from hitting either the cup or the camera lens. For this picture I backed the camera up a bit so you can see both flashes. When I was shooting for real, the camera was on the tripod.

Here is the view from the point of view of the flash (you can see the blurry 580EX at the bottom of the frame). The light from the flash goes through the triangular gap between the black foam core and the backdrop to it the white foam core surface on the other side. That is the light which illuminates the glass. The flash was carefully placed just behind the backdrop and just below the surface of the table to avoid spilling light on either surface which is what keeps the background dead black. What about the triangular shape of the gap? Look at the light on the stem of the glass. You can see the point on that triangle where the stem fades into the background. A nice aspect of this particular setup is that it can be very simply tuned by moving the flashes around. Moving the each flash changes the effective light source direction by changing the illuminated area of the white foam core.

On a final note, I found I need to add a black lid to the setup to control reflections of the ceiling in the glass. Unlike the foam core, my ceiling is white.

FEC with the 5D, ETTL-2 and off camera bounced flash.

So there had been some more water under the bridge since my last post on flash technique. I am still shooting event candids with the ST-E2 on camera and using a variety of techniques to bounce the flash. This shot was taken with the flash sitting on a table behind me pointed at a white ceiling. I mentioned in that prior post that I was typically seeing around a stop of underexposure. Over a number of shoots that has proven to be consistent enough that I now use +1 FEC as my default starting point and work from there. Its annoying because for some pictures with lots of white +2 FEC (the limit on the 5D) is not enough and I have to live with an underexposed shot.