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Night photography for dummiesin Tutorials |
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By pgauthier/Philippe (1,792) 
on May 13, 2002 4:29:42 PM CDT
The equipment you'll need The equipment you'll needTo make night pictures, you need a camera, a tripod and a cable release (or some equivalent device). Any camera with a B (bulb) setting will do fine. The tripod must not be too flimsy, as you'll need to keep your camera perfectly still for several seconds, often in difficult (strong wind) conditions. The cable released is used to fire the shutter without actually touching the camera. This is essential to avoid vibrations, a cause of unsharp pictures.The film I recommend is ISO 100 negative film (B&W or color). Some photographers use very fast film (ISO 800, 1600 or 3200) to shoot hand held under dark conditions. This can be done, but it requires a very good exposure (fast film has less latitude) and the results are quite grainy. You could also use slide film with excellent results, but exposure can be tricky and I'm trying to keep things simple for beginers. Digital cameras have some limitations, especially the cheaper ones. They sometimes have no B settings and long exposures can be limited to 10 or 30 seconds. Long exposures also generate quite a lot of noise, unless you have an expensive model. This restricts the useful of digital cameras in night photography, but they can be used with success under most conditions.
Exposure basicsSetting up the tripod is the same trouble whether you shoot for a 1 second or a 45 minutes exposure. My philosophy is therefore to get the most out of each shot by choosing grainless ISO 100 film and the aperture that is the best on any lens, f8.Therefore, in what follows, the aperture is always expected to be f8 and film rating to be ISO 100. Only the length of the exposure changes. Under these conditions, night exposures are LONG. Your eyes get used to dim light, but film doesn't. What appears bright is actually quite dark. If a tiny fraction of a second is enough light in daytime, you need several seconds at night.
Reciprocity failure compensationThere are two reasons why you can't usually trust your built in camera meter in night shots. The first one is that most can't handle dim light very well; readings tend to be unreliable. The second one is reciprocity failure.What's reciprocity failure? Usually, it doesn't matter if you shoot 1/125 @ f/8 or 1/250 @ f/11 or 1/60 @ f/11: in all three scenarios, the film gets the same amount of light. This is known as the Reciprocity law. Unfortunately, reciprocity fails when the light is dim. Few photons hit the film and chances are that the silver halide crystals won't receive enough energy to be sensitized during the normal exposure duration. Reciprocity failure means that you must increase the actual exposure time, a process called reciprocity failure compensation. If you don't compensate, your pictures will suffer from wild color shifts, severe underexposure or both. All films require some reciprocity failure compensation for exposure times longer than half a second. How much compensation? It depends on the film you're using, which makes things rather complicated. As a general guideline, though:
Adding one stop means that the exposure time is doubled, ie, 10 seconds becomes 20 seconds; Adding two stops means that exposure time is doubled twice, ie, 10 seconds becomes 40 seconds. You can get the correct reciprocity failure compensation time for your favorite film on the manufacturer's web site. Check for what is known as the "Technical data sheet".
Final notesBracket! The approximative exposure method I suggest gives satisfying results most of the time. Some exposure could be off nonetheless. For critical shots, I suggest that you bracket 1.5 stops in both directions. If you do this with print film, you get at least one perfect shot almost 100% of the time. Guranteed.For those who don't know what bracketing by 1.5 stops means, there it is: You shoot once with the normal exposure. Then you shoot again, for about 35% of the normal time. Then you shoot again, for about 250% of the normal time. If your normal exposure was 10 seconds, you would have three shots, one at 4 seconds, the other at 10 seconds and a final one at 25 seconds. Don't use filters! They tend to create flare. Watch from strong light sources falling directly on your lens: they also create flare. Lens shades are very useful in night photography: use them! Beware of contrast! If you mix bright spots and powerful light sources with dark areas, some parts of your picture will ba badly overexposed and the rest, completely lost in shadows. Compose to include subjects as evenly lit as possible.
Examples of exposure calculationIn short, my "meterless method" computes the exposure time in three simple steps:
1. Estimate the available light Example #1. A tall church is lit from the ground up. There are quite a few powerful lights, but they cover a large area. A good starting point is 15 seconds. The building is middle grey, so I don't correct for brightness. My film need a 0.5 stop reciprocity failure up to 15 seconds, though, so I increase the time by 50%. The correct exposure is 22 seconds (25 would be OK too, a few seconds don't matter much when exposure time is so long). Example #2. A bronze statue is lit by a single spotlight. The light is not very powerful, but it's nearby and the statue is reasonably well lit. I chose 8 seconds as a starting point. But the statue is very dark, so I increase the time by 50%. I'm now up to 12 seconds. My film is FP4 and needs a two stop reciprocity failure compensation at that point. The correct exposure is therefore 48 seconds (make that 50). Example #3. Every column of the city hall is lit from above and from the ground. Other interesting architectural elements are lit by their own spotlight. You could almost think it's daytime. It is so bright it almost hurts my eye. I chose 2 seconds as a starting point. The city hall is made of white marble; I therefore reduce exposure time by 50%, down to 1 second. My film is Delta 100 and I need a one stop exposure comepensation; the correct exposure would be 2 seconds long. If you found this article useful, please rate! I have other subjects in mind and popular support will help me overcome my laziness!
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