Time-Lapse Notes on Growing Plants
The Time-Lapse FAQ
By Ted Kinsman
Plants have several requirements needed to make them grow and bloom -
some of these are:
a. Temperature
b. Humidity
c. Light quality
d. Light duration
Of these variables, temperature seems to be the most important. Since I
photograph in a studio that averages 65 degrees in the
winter and 74 in the summer. These average temperatures can be
increased with the use of a variac and a heating pad. The
heating pad is a 35 watt heater used to keep iguanas warm. These
are available from pet suppliers and are a 13 x13 inches
square. These flat heaters can be placed under a pot to supply bottom
heat to the plants. There are also special heaters that are
sold to keep seeds warm for germination. Either heater system works
well.
Morning
lilies 1 min wait time.
Light Duration:
The light duration can be either computer controlled, or a simple house
light timer can be used in series with the computer
controlled relay. Plants will become stressed if lights are left on for
24 hours a day and some will not bloom, or will bloom very
slowly. The duration of lights should be kept close to what the plants
are used to, if plants are collected from the wild, try to
keep the grow lights in phase with the current sunrise and set.
Light Quality / Spectrum
The spectrum of the glow lights can be very important for some
varieties of plants. Morning glories require a spectrum close to
the solar spectrum to insure blooming, the duration of the light is
also very important. The simple act of turning on photo lights
every few minutes can mess up the photo cycle of the plant. Poinsettias
are very particular about having an uninterrupted dark
or "rest" period.
I typically grow plants outside, in a green house, or collect wild
specimens. Recently, I have started collaborating with some of
the professional orchid and water plant growers in the area.
These guys have been a big help in loaning me world class specimens to
photograph, and I have supplied them with some wonderful time-lapse
sequences for their web sites. When a plant is ready to bloom it
is are moved into the photo studio at the
appropriate time to photograph the desired motion. Many plants will
still grow and bloom if a part is cut off and moved into the
photo studio. Things like flowers can be cut, placed in water then
photographed. As long as the action takes less than a few
days the photography can be completed before the plant wilts.
Frequently requested shots like roses take special precautions.
Roses require a thin wire to be wrapped around the stem to insure
proper positioning. Roses will quickly follow a light source.
Roses can also be brought into the studio in potted containers, sprayed
with an insecticide (unless you are trying to photograph
crawling creatures) wired up, and photographed. Of all the flowering
plants, photo editors request roses 10 to 1 over
everything else. The reason is that not many people can film
roses, typically you have to grow your own. Of all the plants
roses are second in difficulty to poppies.
Many plants require special techniques, these process often lead to new
discoveries about the motion of plants. Most plants
have never been time-lapse photographed, so new discoveries are abound.
Many if not most plants exhibit phototropism, that is they follow the
sun. Leaves will rise to meet the light and then bend down
at night. Plants like dandelions will do this on a continuous basis,
while their flowers will follow the sun. This can lead to
problems if the grow light is in a different direction than the
camera's lens. What happens is the plant bends towards the grow
light and away from the camera. A way to control this problem is the
have a large light placed near the camera. This main grow
light keeps the flower, or leaf pointing in the correct direction. Wire
can be used to wrap the stem. This keeps the plant in from
moving.
Datura
Timing:
Timing for plants is best at one shot every three minutes, or a longer
duration is the plant is particularly slow moving. Flowers
that open with the sun such as morning lilies will open completely in
three hours, plan your duration in response to the length of
the final footage. It is often best to test timing and technique for
the specimen before filming.
I believe that most time-lapse sequences should be around 12 seconds.
(many of mine have been digitally edited to a few
seconds) Many times the length of film will be much longer than the
target 12 seconds due to waiting for an event to happen.
An example would be taking a frame every 3 minutes for 4 days, waiting
for a flower bud to open.
In regards to timing, it is always safe to error on the side of taking
frames too fast. Sequences can always be sped up in the
digital editing world. This often happens.
The rule of -thumb is the higher the magnification the shorter the time
between frames.
Grow Lights:
There are many discussions on grow lights that imitate the solar
spectrum. White florescent lights work just as well as the grow
lights for most plants. What is very important is light levels. The
brighter the better. A bank of 6 tubes of florescent lights is very
nice for growing most plants. I grow the plants in a box that is
1meter by 2 meters and 1.5 meters high. the grow lights are the
primary source of heat and lights for the plants. I use an
ultrasonic humidifier to keep the water content of the air fairly high
(at least 75%). The front of the box is clear thermal plastic
that I can cut a small hole for the camera lens. Most of the time
I use flashes for the exposure and these are placed outside the box.
Photo Lights:
There are three ways to deal with this problem.
1. Shoot with fluorescent grow lights on all the - adjust
the color balance for this.
The problem is that many plants will not grow properly
with out special spectrum grow lights. These lights are just
about impossible to get a normal color balance with. If the grow
lights are your photo lights - this also makes lighting
difficult. Keeping the lights on all the time will stress some
species and they will not grow or bloom. The blue morning glory
plant is an example of a species that will not bloom in a lab with out
the correct lighting duration and spectrum. Keep in mind that
many other species of morning glories will grow in the lab just fine.
2. Grow with florescent lights. Cycle them off and on
for proper growth then turn them off and turn on photo lights for every
shot.
The problem with time-lapse photography and lights is the lights have
to turn on and off a large number of times. Fluorescent
lights are designed to do this, but are the wrong color temperature and
spectrum for film photography. Halogen lights that are nicely
color balanced are expensive, hot, stabilize quickly, but must be left
on for a minimum of ten minutes to allow the halogen
chemistry to properly cycle. Although a halogen light will burn full
strength to 75 hours, it will only turn on and off 400 times.
The means that a halogen bulb is a very expensive source of lights, and
fairly unreliable. There is a large probability that the bulb
will burn out during a shoot.
The solution is to use inexpensive incandescent tungsten photo bulbs.
These bulbs are about $2.50 in bulk. These lamps are
balanced for 3200 degrees K and will last for 2500 duty cycles. When
they start to turn brown, I replace them with a fresh
lamp. I keep the used bulbs for photography requiring constant use
lamps. This is the best solution to the lamp problem I have
found so far. This is the best solution for shooting film
cameras, but now is mostly out dated.
3. Grow with cycling florescent lights for best growth, then
use a photo flash to get the exposure.
This option is the best for digital photography, and also the easiest
to set up. The plants are placed in the grow box and lit with
fluorescent lights for the growth cycle. I mostly use two banks
of two lights - these supply quite a bit of heat and keep the
grow area in the low 80's F. The grow lights are on for 14 hours
off for the rest of the day. The grow lights are controlled
independently from the camera by a simple light timer. The camera
is driven by a time-lapse controller and monolights are used for the
exposure. Monolights are stand alone flashes that are now quite
reasonably priced. A simple unit can be found for about $125 in
the US. These flash units can be triggered by a sync cable or an
other flash unit. I use a PC cord to control the flash from the
camera. This connection must be taped down with camera tape,
since during operation the PC connections often loosen and break
contact.
To set the exposure make sure that the camera shutter is set to the
fastest shutter speed that is able to synchronize with all your
flashes. The correct exposure need to be at last 5 exposure stops
above the normal exposure from the grow lights. This set up will
also have the added advantage of taking the shutter variation out of
the camera exposure and the resulting set of images will be much more
consistent.
It is very important to test your set up before a big shoot.
Shake out all the bugs (electrical problems and real bugs too) before
you start a real sequence of images.
Click here to move to Chapter Six of the Time-Lapse Photography FAQ
