Lighting Architectural Interiors

(All photographs © John Wm Nagel unless otherwise noted.)

In an earlier post (Breaking the Law) I alluded to some of the challenges of photographing architectural interiors; namely, that the constantly changing pupillary adaptation to brightnesses produced a nearly uncanny effect of great visual dynamic range. As we observe shadow areas our pupils enlarge and as we observe brighter areas they contract. This is a great advantage over photography in that pictures are made with a single aperture setting. It IS possible to multiple expose an image and change the aperture between exposures, but this also changes the dimensions of objects in the image and causes ghosting in nearby elements. So it is best to leave the aperture unchanged.

Fox Theatre, Auditorium

In photographing the Fox Theatre in 1981, I used a painting with light technique that I read about in Ansel Adams's book, "The Negative". The Inverse Square Law requires, however, that a surprisingly great amount of light be directed to distant dark areas, while limiting near objects to brief illumination. For most commercial applications I was using an electronic flash combined with ambient lighting. My approach was to augment the existing light by filling with flash exposures to interpret the visual "experience" of the room into something that film could record.

I normally used two power packs, 2,000 watt seconds each. At the camera position usually one or two umbrellas would carry the master illumination of the picture. Then devices such as snoots or grids would channel light into the recesses of the subject. Sometimes a remote fill light would be positioned further into the set and triggered by a "slave".

Exposures were often measured with a flash meter; but, more often than not, simply tested with Polaroid film in the 4" x 5" view camera. Exposures were always divided into two components and simultaneously controlled. The ambient light was derived from the length of the exposure. The added "fill" light was a product of the number of exposures.

Here is how it works. Electronic flash is synchronized to the shutter up to 1/500th of a second. Imagine a living room space with all the lights turned off, perfectly dark. With electronic flash an exposure of 1 second and an exposure of 1/500th of a second would produce the same effect on the film. This is because the duration of light from the flash is usually less than 1/2,000th of a second.

Living Room #1
Combination of Ambient Light and Electronic Flash

An interesting digression at this point would be the work of Harold Edgerton, modern inventor of electronic flash*, and the interesting experiments he conducted using the burst of the flash as the duration of the exposure. Electronic flash is very bright, but also very short. By using the flash duration alone, Edgerton was able to stops bullets in midair and investigate all kinds of phenomena previously invisible to the human eye, such as the crown formed by a splash of milk or the frozen wings of a hummingbird.

Milk Drop Coronet
© Harold Edgerton

Bullet Through Jack
© Harold Edgerton

In our dark living room picture, suppose we turn on the lamps. At 1/500th of a second, they would still be all but invisible, but now we could lengthen the exposure to 1/2 second as an example. The amount of light supplied by electronic flash would be the same, but the ambient light would add significantly to the exposure of the room by adding pools of light wherever they occurred. By balancing the two components of ambient and fill light by virtue of the shutter, pretty good pictures could be made simulating the visual response to the room.

Living Room #2
Combination of Ambient Light and Electronic Flash

If the ambient exposure was best at 1 second @ f/22, and the fill light was best if it were doubled, then two exposures at 1/2 second would be used. The shutter would simply be re-cocked and fired again for the second exposure. Eventually I purchased "press" shutters for all my view camera lenses; these shutters re-cock automatically eliminating the danger of moving the camera or lens. In this fashion two, three or four times the electronic flash could be added to one ambient exposure.

Living Room #3
Combination of Ambient Light and Electronic Flash

Another dimension to the challenge was whether to use film balanced for "daylight" or for "tungsten" light. This is another factor human vision also takes care of automatically. We adapt to the color of light so that all variations seem normal to us, when in fact exterior daylight is quite blue compared to rather yellow interior tungsten filament bulbs.

Living Room #4
Combination of Ambient Light and Electronic Flash

Electronic flash is matched to daylight and since in my interior photography the fill light was the dominant source, I used daylight balanced film. The additional warmth of existing lamps was never strong enough to be a concern. Also it was possible to balance daylight exposures with windows more easily.

Office at Laclede's Landing with Ead's Bridge in Background
Combination of Ambient Light and Electronic Flash

Office Interior
Combination of Ambient Light and Electronic Flash

*The first electronic flash exposures were made by William Henry Fox Talbot as early as 1851! As an experiment, Talbot attached a copy of the London Times to a spinning disk and exposed it to an electronic light source. Even though the newspaper was spinning quite rapidly, all the letters could be clearly read; the duration of the light source was so brief and intense. See an excellent article by Jon Tarrant on the history of photographic lighting here.