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One can run into seemingly impossible ranges of illumination in sunlit scenes also, but there is another factor that makes a night scene even more challenging. Films have a "feature" known as reciprocity failure. What this generally means is that light of less than a certain intensity will fail to add as much exposure over time as brighter light. This is usually affects longer exposures, and film reciprocity failure is usually expressed by the amount of exposure that needs to be added for a certain time exposure. As an example; if you shoot a 30 second exposure on Kodachrome you must added 1.5 stops (accomplished by changing aperture, not time!). But there is another way of thinking of this.
Reciprocity failure is really a result of the film having a threshold area below which it loses the ability to record the light falling on it. One could say the human eye has similar limitations, but that it is far more sensitive than any film/lens combination. It also scans a scene and assembles it, of course, habitually (perception, and all that it misses, is a matter of habit, but you knew that!). So the eye will always see more range in a city scene than will a camera. Now if we find that scene moving, rich, etc., we may want to approximate its appearance with photography. But let's be realistic and admit that we can only describe it with a camera. Experimentation is the only way to get to know black and white materials. You don't know what's possible until you try a few stupid, impossible strategies and fail. Processes are often interesting at their edges, which is where they begin to fail. Most importantly, and this will sound disgustingly cosmic, every complex process has a personality. You won't experience this following the path of the well-informed. That's a lemming in line in front of you.
My first area of experimentation, the goal of which I thought was contrast reduction, was ultra-compensating development. It is fairly hard to find these developers, but Edwal used to make a two-bath version (discontinued). It was very good at reducing contrast and retained or improved on rated speed. It produced very unpleasant and unrealistic (to my eye) prints of night scenes. They looked flat, dead. I tried Microdol-X, 1 to 3 dilution, and rated Tri-x in the 50 ASA range with a %40 reduction in the usual development time. This is possible with 4X5 film, but can cause a drastic boost in grain when attempted with 35mm film. However, too much speed was lost, which in effect just increased reciprocity failure. Then there was Rodinal, which was interesting on 4X5 but contrast once again began to rise, and highlights became blocked and unprintable. For a number of years I've used D-76 undiluted, followed by a water bath which is a full 8 degrees above the developer temperature. A bit mundane, eh? The 400 speed film is rated as low as 50, sometimes even lower. The scene contrast intensity determines the time in the water bath. There is definitely a limit, because the emulsion itself can swell and become detached. When possible I use a grey card for exposure measurement, held in an area of the scene where I want mostly mid-tones. An incident light meter would accomplish the same thing, but is not sufficiently light sensitive due to the diffusion dome. I develop each 4X5 sheet individually, because sheet film tanks are particularly difficult to agitate without streaking the film. 120 film is easier. It's extremely important to simply move the film to the water bath, you can't just empty a tank and fill it with water. You must take the film gently from the developer and put it gently into the water bath, or you'll get obvious streaking. You want the residual developer to remain in the emulsion when you put it in the water.
Another method for improving the lighting on night scenes is to use flash. However, in my opinion this will only work when it is impossible to tell that flash was used. In other words, the flash must be used in a way which imitates the existing lighting. This sounds very difficult, but in fact, isn't. Most light sources at night are "point sources," an optical term. This means that the size of the light source is very small in comparison to the subject size. A street light is a good example of this. Point sources throw distinct shadows and cause a very high scene contrast between the lit and unlit areas. Electronic flash (without reflectors or soft boxes) is also a point source at night, as long as it is a reasonable distance away from the subject. About the only time it is not a point source is in macro photography. In many of the night shots that I've taken have powerful flashes were used to augment the existing light. The flash must be a good distance from the subject, and firing it through bushes or something similar will add shadows. Sharp shadows really help define the shapes they fall on, as they bend around corners, etc. They also add to the mood of the picture. In fact, in lighting an object like a car, etc., it's much better if only part of the object is entirely illuminated. As an example, look at this image from the "Car Series." The rear of the car is in complete darkness, but with the light on the front, and the eye/mind grip on perspective, the rear of the car is implied. I like playing with this part of perception, where one moves from puzzlement to recognition. It is also possible to light very large areas in a similar way with one of the older style "screw base" flashbulbs. These bulbs have a standard light bulb type screw in bottom, so you can use standard flood lamps as holders, and standard extension cords to set them off. You have to have an adapter which will allow the connection of the 6 or 12 volt battery to actually fire the bulbs. Photographs taken in a recent National Geographic of the largest known cavern in the world were done using these antique flashbulbs. The originator of this technique may have been O. Winston Link, who photographed trains at night. In a bizarre story, his wife held him captive in his darkroom and then stole about a million dollars worth of his art prints, which were never recovered. Check it out. What the shutter is doing during all this is, nothing. I will usually lock the shutter open and actually use the lens cap to start, and end, the exposure. The time of the exposure is estimated from either a meter reading or experience with other night shots. However, seldom is overexposure much of an issue. If, in the process of adding flash exposures, or using a flashlight to paint light, you run over your expected exposure time, not to worry! This is where the reciprocity failure is a boon, because the exposure will usually take longer to accumulate than your estimate. For an extreme example of this, click here. However, it is very possible to overexpose with the flash or flashlight, so care must be taken here. The flash exposure is best determined by the distance chart derived from the "guide number." Over the years I've developed a consistent method of painting with a flashlight which aims at giving all areas about a second of exposure. This where experimentation is very necessary. I've gotten a fair share of questions about moonlight exposures, etc. Since I find urban and suburban land/city scapes most interesting, I haven't done much with moonlight. Frankly, the light level is so low that you might just have to shoot on 35 mm where you can find lenses with large apertures. Secondly, a very distracting thing that the moon and stars do is rotate in the sky over time, leaving circular trails in time exposures. I intentionally avoid this by shooting on overcast nights. Some photographers find the effect interesting, but for me it doesn't approximate what the eye sees in the scene. To summarize, approximating that stark beauty of a night scene is the ideal to move towards in night photography. We can't quite get what the eye sees, or the mind remembers, but we can get close. Experimentation and the gut-level knowledge of materials and methods that come with it are the key elements to learning how to capture night scenes. |
often get asked about the specific techniques I use in taking night
photographs. In order to focus the discussion, lets assume we're talking
about night cityscapes, which is probably an apt description of the
majority of the night photos I take. To clarify, these night scenes
are usually lit by streetlights or other point sources and have an
incredibly wide range between the lightest and darkest areas of the
scene. 
