A little lighting project

Today I decided to learn something about lighting. I wanted to photograph a little still life on the corner of my desk so that it looked about the same as it did to my eye. The project was more difficult than I expected. It took about 200 shots and two ProFoto B1 flash units to get close, but none looked exactly the way I wanted. To get that, I think I would have needed a way to suspend at least one of the lights outside the window, facing in. That said, the final results got close.

The first issue was the focal length. I started with an 80 MM lens but it was too long, so I switched to a 55 mm SK LS. Second was the depth of field. To my eye, everything from the bottle in the foreground to the bricks in the background were in focus. The closest I could get to that was to shoot at f/22, the narrowest aperture available on that lens. That aperture increased the depth of field considerably, but left the foreground slightly more blurred than it appeared to my eye. All were shot at 50 ISO.

At f/22, a long shutter speed was required to collect enough light for the scene. On the opposite end of the spectrum, at f/2.8, there was plenty of light but a shallow depth of field. I liked the look of it, but made many test shots throughout the entire range to find the best balance of light and depth of field. Failing that, the exercise covered the full range for the sake of better understanding what could be expected with backlit subjects like this.

The lighting challenge came from the brightly lit exterior and the interior, which my eyes saw as well lit. The camera, on the other hand, looked at the interior as very dark if the exterior was correctly exposed. The other extreme left the interior correctly exposed and the background over-exposed. Of the two, exposing for the background looked much closer to what my eyes were seeing.

I set up the two B1 heads to illuminate the interior, in the hope I could approximate the result of what I saw naturally. Because of the objects in the room, the B1 units would cast unwanted shadows if they were aimed at the sculpture at the center of the scene. For that reason, the key light was pointed at various parts of the ceiling or walls in front of the sculpture. The other light was used as a fill light source. It was pointed at the walls or ceiling behind the sculpture. This created a soft bounce light from both light sources.

The final images don't have the same depth of field as what I could see without the camera. That might have been solved by using an SK LS 80 mm lens, because it can shoot at f/32, but to use it, the room would have had to be larger. Another difference is that in all of the four best images, the sky is brighter than it looked to my eye, the highlight on the sculpture had a slightly different shape, and the contrast between the dark side of the sculpture and the window shade was less.

Here are the four closest images, and the settings used to make them:

f/2.8, 1/4s Light levels are close. Highlight on left of sculpture is good. Depth of field is the farthest from what I was seeing. Individual bricks in the background building are not visible, but should be. Contrast should be greater, but if adjusted in post, the balance of exterior and interior light levels is less accurate.

f/2.8, 1/50s. Light levels for interior are closer than in the previous shot exposed at f/2.8. The background, however, is less accurate, in the direction of being over-exposed. Contrast is less than it should be, but better than the previous shot.

f/10, 1/6s. Depth of field in this shot is more accurate than the previous two. The highlight on the sculpture is less distinct than it should be, and the shape spreads over the chest too much. Light levels for the interior are lower than they should be, but the background is about right.

f/20, 1s. Interior light levels are brighter than in the previous image, but the background is over-exposed. Contrast and depth of field are good. The shape of the highlight is the least accurate of the group.