Time-Lapse Notes on Growing Plants
The Time-Lapse FAQ

By  Ted Kinsman

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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.
















 

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ekinsman@rochester.rr.com

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