Long Exposures

Long exposures are any exposure over about a second or so. They can be a little tricky to pull off, especially with the Holga's lack of controls. Luckily, there is one main control you need, and that's Bulb mode. Most of you will have encountered this mode, probably at the expense of your first roll of film. This mode allows the shutter to stay open for as long as you hold the shutter button, which is perfect for capturing low light. Without wishing to go any further off-topic, here is a list of vital equipment you will need:

• A Holga set to bulb mode
• A cable release
• A tripod (or solid surface)
• An exposure guide, or digital camera

So, firstly, set your Holga to bulb mode. You might want to tape a note on the back to remind yourself to switch it back after you have finished experimenting with long exposures. Next, you will need a way to keep the shutter open without holding it. A cable release will do nicely. Now attach your Holga to a tripod, which should allow your pictures to still be sharp. If you don't have a tripod then you can either put your Holga on a wall, or the floor. Or you could even try making your own bottle cap tripod. Finally, you will need a way of calculating your exposure. You can either use an exposure guide or a digital camera. Using a digital camera is preferable as you get to see what the final picture should look like. You can only use digital cameras that display aperture and shutter speed on screen. Ideally you should be able to set the digital cameras aperture to f/13 (or what ever you've modified your Holga to be).

What to shoot...

Now you will need to decide what to take a picture of. If you are looking for inspiration, then there is plenty on flickr. The most common, and visually appealing subject seems to either be cars on a busy road or water. Think about shooting subjects that are in motion, for example: cars, water, people, carnival rides. Moving subjects seem to take on a soft and ghostly appearance when captured with slow shutter speeds. Here are a few nice examples of long exposures:

Exposure

Figuring out exposure times can be tricky at the best of times, but night time photography is much harder. Nailing exposures at night is equal parts experience, and good luck. In order to increase your chances of getting a decent image, first find out what your exposure time should be. You can do this one of two ways; use a digital camera with aperture priority mode (labelled as A mode), set to f/13 and then read the shutter speed from the cameras display, or use an exposure calculator. The exposure calculator should give you a rough idea of where to start. If you are unsure about the exposure, you should take 2 pictures; 1 taken at what you think the exposure should be, and 1 for twice as long. This is a common technique called exposure bracketing.

Bear in mind that for long exposures, you have a much greater margin of error with long exposures. If your indicated exposure time is 2 minutes, you would have to expose the film for a further 2 minutes (4 minutes in total) for it to be only 1-stop overexposed. Note that negative films are very tolerant of overexposure. In fact I know a certain photographer who has managed to get beautiful images from film overexposed by a whopping 10-stops! One thing that will drastically affect your exposure time is reciprocity failure.

Reciprocity failure

Reciprocity failure is where the sensitivity of a film changes over time. Basically this means when shooting long exposures, you need to allow more time than a light meter would tell you. Each manufacturer tells you how much extra time to allow in their data sheets for their film. Not all manufacturers have good data sheets; Fujifilm and Ilford seem to be nice and detailed, whereas Kodak doesn't really help much.

Chris Hoge has created a fantastic calculator to help people realise how to expose images, accounting for reciprocity. To use the calculator, set the "Actual f stop" to 13, and set your "Meter f stop" to whatever aperture you are using on your meter (or exposure calculator). That should give you a rough guide. Let's create an example: we are using Ilford HP5+ 400 ISO film and taking a picture of a street, where the only light are street lights (EV 3). The meter says we need a shutter speed of 4 seconds for an aperture of f/11. For our aperture of f/13, that would be an exposure time of 6 seconds. Taking reciprocity into account, it would end up being 13 seconds.

Most data sheets will let you know when you start giving extra time. Here are a few examples:

• Ilford HP5+ - 1/2 second or longer
• Fujifilm Acros - 2 minutes or longer
• Kodak Portra 400VC - 10 seconds or longer
• Fujifilm Superia Reala - 4 seconds or longer
• Fujifilm Velvia 100F - 2 minutes or longer

Recommended films

As strange as it seems, slower speed film (e.g. 100 ISO) seems to suffer less from reciprocity failure. That is not to say that faster films are too awkward to use for long exposures, but you may have to allow more time. From my research, it seems like the easiest film to use is either Fujifilm Acros (100 ISO, black and white film), or Fujifilm Velvia 100F (100 ISO, slide film), as they require very little in the way of reciprocity failure compensation. If you have any recommendations, please let me know!

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