Night-time long exposure photography can be intimidating, especially when shooting on film where the results are not instantaneous. On digital you simply try an exposure setting and see immediately what those settings accomplished; this makes it easy to adjust for the optimal exposure. Not so with film photography.
"Contact Sheet" from a single roll of 120 night photography.
You only need three things to get started with long exposure photography at night! It's fairly simple:
a camera with a BULB setting or options for 10, 20, 30 second shutter times.
film: 100, 200, or 400 speed are all fine options
With film, I recommend going with black and white first. This way you don't need to worry about the unpredictable colors that street lights often give off, you can focus on gradients and patterns and qualities of light instead; brightness and darkness.
An additional thing you might want, but isn't totally necessary, is a shutter release cable or wire shutter lock. This allows you to not bump your camera by accident when engaging the shutter. A bumped camera can result in an undesired blurry image.
So the sun has gone down and you head out to shoot.
What do you want to capture? Light streaks? Stars? City scenes? Movement? Think about the locations where you can photograph these things: with stars you want as little outside light pollution as possible, with movement you want to find a busy road with lots of cars zooming by. Do you want to highlight lines or shapes or architecture? Where is the best place for that?
Find your spot, set up your camera and tripod, and get the focus dialed just right.
It's important that you stay safe. Keep an eye on your surroundings. I like to carry pepper spray. Be cautious and smart. When we're shooting we're often zoned in on our viewfinder. Night shooting is a time when you need to be much more aware.
Decide on your exposure.
The Aperture affects two things: 1) how much light reaches the film, and 2) the focus of light reaching the film. At night, on a tripod, you can expose the film for as long as you want, so using aperture to get less or more light isn't a huge concern. I find that my main use of aperture is: do I want a specific area or object in focus (low f-number, wide open aperture), or do I want everything to be in focus (high f-number, small aperture)? Then I adjust the shutter accordingly.
The Shutter affects how long your film is exposed to light. Unless it's super bright, at night you're going to want to keep your shutter open for anywhere from 3 seconds to 1-minute. This is where the fun/guessing game begins. Film basically starts as a black canvas. As the film is exposed to light that black canvas begins to get brighter and brighter and brighter.... and if you leave it exposed too long it goes fully white (over exposed). So your goal with night photography is to make your best possible guess of how long to expose the film to get it bright, but not over bright.
And that's the process!
Thankfully I have found that night photography is pretty forgiving. The "correct exposure" is subjective and an image can look great in its own way through a multitude of brightnesses.
Show Me Examples!!!
Now you're asking, "Okay Steven, can you just tell me what settings to use?!"
Because I want you to learn, I'll give you some examples and approximate settings, so you can understand the thought process and reason for various settings:
Busy highway. A tiny bit of twilight on the horizon.
Film ISO 100, Aperture f2.8, Shutter about 10 seconds
Very dark area. Not much light around. No lights in the windows.
Film ISO 100, Aperture f4.0, Shutter about 60 seconds
Parking garage. Lights all around. Wanted tight focus on this arrow.
Film ISO 100, Aperture f2.8, Shutter about 3 seconds
Busy highway. Shooting through a fence. Wanted more in focus.
Film ISO 100, Aperture f11, Shutter about 30 seconds
Go forth and shoot!
The best thing to do is just go out and TRY! I recommend bringing a notebook and jotting down what settings you use for each shot so you can learn from it. You may even want to try the same shot with different settings to see what happens (for example: f2.8 for 10 seconds, f2.8 for 20 seconds, f2.8 for 30 seconds or mix it up another way). You likely will have a few shots underexposed or overexposed. But as I said earlier, long exposure night photography is pretty forgiving, and you'll learn as you go.
I hope this little guide was helpful! Now go forth and shoot!
A Note on Reciprocity Failure
Another challenge when shooting long exposures with film is something called "reciprocity failure." In his book "Mastering Film Photography" Chris Gatcum explains,"When exposure times become very long, the film effectively becomes less sensitive, because of the small amount of light reaching it. And when this happens the exposure required increases exponentially."
So what does that mean? With long exposures on film, you generally need to expose it longer than you would a digital shot for the same affect. I honestly don't think it's necessary, at least when you're first getting into this, to know how to adjust for reciprocity failure. But if you really care, you can use denisoliver.com/long-exposure-calculator/en/ as a good source for figuring out how to adjust your exposure properly. The problem I've found is that "the exposure required" isn't entirely definable. If you hold a light meter up, it doesn't know it's nighttime or what affect you're after. It just knows "do this setting for balanced light," which during the daylight is pretty reasonable, but at night can be something very different. Anyway, that's just my two cents.