Instant Strip Photography
Rochester Institute of Technology
School of Photographic Arts and Sciences
Rochester, NY 14623
Strip photography is a technique in which photographs are
made by a process that falls somewhere between a that used in a motion
picture camera and that used by a regular still camera. As in standard
photography, strip photographs are viewed as 2-dimensional paper prints
or transparencies but unlike regular photographs they resemble motion
pictures because they are made over time. In a very special way, strip
photographs are pictures of time itself. They are reproductions of what
happens over time at a particular location in space.
Strip cameras come in many different shapes and sizes and are
often designed for specific applications. Among the more common cameras
that depend on the strip method to fulfill their objective are certain
panoramic cameras such as the Globuscope, the Hulcherama and the
vintage Cirkut panoramic camera. More specialized are the photofinish
cameras typically used at racetracks and other sports events for
determining the winning order in races involving a close finish. Even
more specialized are synchroballistic cameras and peripheral cameras.
Most strip cameras are quite expensive because they are
specialized. Because of this the potential for applying these cameras
on a more general basis has been slow in gaining popularity. In this
article I will describe how to modify inexpensive Polaroid cameras
(these days probably using Fuji instant pack film) to exploit this
neglected field of
In order to make a strip photograph all that is required is
to move the film past a narrow slit installed just in front of the film
plane while the image of the subject is made to move over the slit.
Generally it is desirable to make the film move under the slit at the
same rate as the image is moving over it.
While 35mm cameras can be adapted to for strip photography by
installing either near the film plane or out in front of the lens a
narrow vertical slit and then rewinding the film while the shutter is
open there is also a way in which one can be more readily experiment
with this process using Polaroid materials.
While I conducted successful experiments with motorized film
ejection cameras the approach that proved much more successful involved
the use of Polaroid film pack type cameras.
The first thing to realize is that a 600 series Polaroid film
pack is designed a very special way. The negative material faces the
lens at the time the exposure is made and then later, when you are
about to process the film and you pull on the film positioning tab,
typically a white tab, you actually pull the negative around a curved
metal edge at the other side of the pack. This eventually brings the
negative face-to-face with the receiver sheet. Therefore, while you
pull on the positioning tab in one direction the negative in the camera
is moving in the opposite direction.
Therefore, to make a Polaroid pack-type camera operate as a
strip camera the first step is to install a stationary mask over the
film pack image gate leaving just a small opening about 1 mm or so wide
near the leading edge of the pack as shown in the illustration. Note
that the leading edge is the one away from the white tabs. I made the
mask out of exposed and developed Kodalith sheet film because it is
thin, quite dense and is easy to cut and install just over the cover
sheet on the pack. The mask is cut so it is slightly larger than the
image gate and slid under the edges. Then it is taped in place so that
when the film underneath it moves it remains firmly anchored to the
plastic edge of the pack.
After the pack is prepared with the mask the pack is inserted
in the camera and the protective cover sheet is removed. The camera is
now set for the first "strip" exposure.
At this time the camera is aimed in the general direction
where some kind of action will be taking place and the shutter is
opened. The shutter must remain open for the length of time that it
will take you to withdraw the white film positioning tab.
This is not too difficult to achieve with most cameras. With
Polaroid cameras equipped with adjustable shutters, the shutter is
simply set to T or B and locked open. With automatically controlled
exposure time Polaroid cameras one solution is to place a piece of
opaque tape over the photocell. The metering systems will be setting an
exposure time that may last as long as 5 to 10 seconds and this should
give you ample time to withdraw the processing tab for most
Since the film must be moving past a slit inside the camera
for a strip exposure to take place, it is obvious that if most of the
image gate of the pack is covered with an opaque mask, the film will
not "see the light of day" until pulling on the white tabs makes the
film pass under the open slit.
When you pull on the white tab the unexposed film passes
under the open slit at the front of the pack where it is briefly
exposed. If the subject was stationary then a bunch of lines should
appear across the print representing the brightness and color
distribution of the subject along the slit during the time it took the
film to pass by the open slit.
For orientation and aiming purposes you should remember that
the "slit" is located at the right edge of the viewfinder frame when
the camera is held normally.
The rate at which the processing tab is pulled out will
determine the exposure time that the film receives. You then adjust the
aperture and/or the lighting level to properly expose the type of film
that you happen to have loaded into the camera.
The actual exposure time can be calculated by multiplying the
width of the slit in the pack by the time you will take to withdraw the
white processing tab and dividing their product by the length of the
tab that you withdraw. Assuming that you are working with 3 1/4 x 4 1/4
size pack film and the slit you left in the pack is about 1mm in size,
and it takes you 5 seconds to pull the white tab out completely and it
is 4.5 inches or about 100 mm long, the exposure time would be 1mm x
5sec / 100mm or about 1/20 second.
If you place the camera on a tripod or hold the camera steady
and ask a person to run quickly in front of the camera while you pull
the film past the slit your camera operates as a photofinish camera.
Remember that the image must move in the same direction as the _film_
and at approximately the same speed.
To photograph a runner, for example, your subject must run
from left to right and it will be recorded as it passes the right side
of your viewfinder.
To determine approximately how fast you should withdraw the
white tab estimate the number of seconds it takes your subject to cross
your viewfinder. That is approximately how long it should take to pull
the white tab out of the camera.
If you ask your
subject to sit on a rotating stool and turn quickly while you aim the
"slit" at the rotating figure your camera will be behaving like a
peripheral camera. You should make sure that you are aiming the right
edge of your viewfinder towards your subject. Determining the time it
should take you to pull the white tab out of the camera is a bit more
difficult for this application but a simple test will tell you if you
are going too fast or too slow.
If you hold the camera in your hand or "pan" it on a tripod
turning the camera counterclockwise while pulling on the tab and making
the exposure, your camera will be behaving like a panoramic camera. The
old "Cirkut" panoramic cameras made wide angle pictures that covered
360 degrees this way. Since the actual length of a panorama is governed
by the focal length of the lens you will only be able to include an
angle that basically matches the normal angle of view of the Polaroid
camera's lens. However, you will probably have much more fun taking a
scanned wide angle panorama than a simple "straight" shot of a scene.
Besides, once you are scanning a scene it is easy to introduce
interesting alterations to the image.
slight drawback to using standard automatic Polaroid pack cameras
for this purpose is that you have to remember to point the camera at an
angle in order to place the sensitive slit on your subject. To correct
for this I cut the plastic snout off the front of my Polaroid
Color-Pack camera and moved cone over so that the lens now sat directly
on front of the slit. Now I knew that the slit in the camera was aimed
at a line that exactly cut my viewfinder in half.
In the process of moving the lens assembly over in my Color
Pack camera I also decided that the lack of an adjustable diaphragm in
the camera was somewhat of a limitation. So I disassembled the shutter
assembly, removed the shutter and installed a diaphragm between the
lens elements. I still have not calibrated the settings on the
diaphragm. Since I operate mostly by test anyway having the possibility
to adjust the light level by altering the aperture instead of having to
use ND filters was a great advantage.
Removing the shutter is advisable but not required. I did it
because since exposure takes place by moving the film past the slit,
the shutter is actually superfluous while making pictures because it
has to be open all the time anyway.
As shown in the illustration, if the manual pull approach is
too crude for your taste, the system can be motorized fairly easily as
shown in the accompanying illustration. Some means for tightly clamping
the white tab needs to be devised. This clamp could be a small "C"
clamp. The clamp is connected via a flexible steel cable (I have used
leader wire from fishing rigs) to the shaft of a small, high torque, DC
gearhead motor. The motor itself has to be held in a fitting that
locates it far enough away from the edge of the pack to allow the full
length of the white tab to be pulled out of the camera. I have powered
my motors with batteries or with a stepwise variable DC transformer
that puts out 3, 4.5, 6, 9 and 12 volts DC. The variable voltages
provide variable speeds which in turn are matched to the speed a
variety of subjects demands.
Obviously, it is not easy to bring a system like this under
as tight a control as is possible with other cameras, such as possibly
a 35mm camera, at least this approach to making panoramic, photofinish
and peripheral can be investigated. In general the system is most
applicable to learning the principles involved in strip photography
rather than being one of absolute technical perfection. Experimenting
with this technique should also provide you with a new vision which
truly incorporates _time_ into your photographs.
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If you would like to discuss this article or strip photography in
general you can write to me at
Andrew Davidhazy, email@example.com