In order to create a long exposure with The Impossible Project’s (or old Polaroid) pack film the easiest camera to use is either the any of the classic SX-70 line or the newer SLR-680/690 cameras (which I use). The main technique is as follows:
1. Set up the camera on a tripod
2. Aim, focus, and trip the shutter
3. Reach along the right side of the camera and drop the film door as if you were going to change the film (important: Do not actually change the film pack)
4. Time your exposure
5. Close the film door
6. Trip the shutter again
7. Collect your image when it comes out
The explanation here is simple. The film pack also contains a six-volt battery. Depending on the model this battery powers the flash, the sonar focus, the electronic eye for exposure, the roller motor, and, most importantly, the solenoid that opens and closes the shutter. By opening the film door the battery circuit is cut and the camera cannot close the shutter without that battery power.
When the film door is closed at the end of the shot the solenoid then closes the shutter. However, the film pack has not passed through the rollers that break open the chemicals and actually develop the negative. That is what the second shutter button press is for. Depending on the model it may do up to a 7-14 second long exposure (you can hold your hand over the lens if you are concerned about a double exposure) and then push the film through the rollers.
As Polaroid is out of business, The Impossible Project is the only manufacturer of film that has not reached its sell-by date. They have three main types depending on your camera: the SX-70, 600 series, and Spectra cameras. Within those one can choose either monochrome (called Silver Shade) or color. Depending on what they are making at the time, options for different frames.
If I’m using the monochrome film I vastly prefer the black frame, as I find the white to throw off the contrast of the actual image. Their new color formula is also greatly improved over their initial foray into the medium, but the opacity layer (the dark layer that prevents the film from getting light when it comes out of the camera) takes a very long time to dry to its clear state, about ten minutes. This is very useful on sunny days however, as your images will no longer be overexposed.
When out shooting at night I also bring along a digital camera for use as a low-level light meter. I set the ISO to 640 (again, I’m using the SLR-680, SX-70 cameras will want to use ISO 100), use f8 (both camera types have an f8 lens), and determine what the correct exposure time is. Reciprocity failure only starts to be a factor in exposures over 10-15 seconds, so anything less and there should be something on the film. From 15-30 seconds I add a stop. For anything over 30 seconds it becomes at 2-1/2 stops. I have not finished experiments into the 10 minute or longer measured exposures, but hope to finalize those general numbers in the near future.
The other main element in my bag is a small LED flashlight capable of an array of intensities from 9 lumens to almost nine hundred, the Fenix TK35. This allows me to add my own light painting to the scene as I deem necessary. If it is an overly complex lighting idea in darkness that involves a lot of flashlight movement or coming from several directions (such as “Anchor Chain” or “The SX-70”) I will use my digital camera to work out intensity levels and determine the lighting composition. Working this way allows me to instantly see what is working and what isn’t without having to spend $3 on film and wait ten minutes for the opacity layer to clear.
If I know I will be planning on a lot of light painting with color film I will bring along a set of gels with me to give myself the flexibility to use that color. “Rainbow Steps” is an example of this taken at the New York Impossible Project space. The One-Step has a small vibrant rainbow detail at the front and seeing a wall of these models gave me the idea of lining them up and coloring them with light to echo the sticker.
I still find the process to be experimental as The Impossible Project works out their film and I work out what I am shooting under various conditions. I also find that sometimes you just let the camera use its electronic eye and see what happens. “Lo-Fi Sci-Fi” came out much better this way than when I tried several timed long exposures, so with a little ingenuity in conditions Edwin Land never considered even after thirty years these cameras are still capable of capturing what photographers are trying to share.