Angraecum leonis

Sunday, May 12, 2013

Whats Light Got To Do With It? Part Two

     The presentation titled "Whats Light Got To Do With It" was given to the Boca Raton Orchid Society just a few days ago for the first time.  It was accepted very well by the members that were in attendance.  This post is a review of a post dated back in July 2012 and also a few bits of new information as well.
     I think it is imperative to understand the basic explanations of light when an experienced grower gives a hobbyist (especially a beginner) the light parameters for a plant to grow and eventually bloom.  I have witnessed to often a hobbyist nodding their head and walking away not really understanding what the grower has said.
     At any of the presentations that I give, I thoroughly explain to the audience to take a few moments and research the plant they have purchased.  The are numerous websites, forums and blogs that can supply specific data regarding just about any orchid in our collections. 
     Specializing in the Angraecum Alliance, I have reviewed many of the specific requirements for well over 600 species.  The light requirements will range from deep shade to bright sun light through various parts of the day. 
     It is very common to see a plants light requirements be given in the measurement of footcandles (fc).  Below are several different ways to measure the intensity of light so that you can determine where to place your plants (any type of orchid or plant) so that they can thrive and bloom as they should.

Measuring light levels with a Digital SLR camera:
     Set the ASA or ISO to 100
     Place a piece of white paper in the area you want to measure
     Fill the view finder of the camera with the white paper and be sure that your shadow does not
          interfere with the white paper (it is not necessary to focus)
     Take a meter reading, the following shutter speeds and fstops represent the following:
          1000 fc - 1/2000 @ f2.8
          1000 fc - 1/1000 @ f4
          1000 fc - 1/500 @ f5.6
          1000 fc - 1/250 @ f8
          1000 fc - 1/125 @ f11
          2000 fc - 1/2000 @ f4
          2000 fc - 1/1000 @ f5.6
          2000 fc - 1/500 @ f8
          2000 fc - 1/250 @ f11
          2000 tc - 1/125 @ f16
          4000 fc - 1/2000 @ f5.6
          4000 fc - 1/1000 @ f8
          4000 fc - 1/500 @ f11
          4000 fc - 1/250 @ f16
          4000 fc - 1/125 @ f22
          8000 fc - 1/2000 @ f8
          8000 fc - 1/1000 @ f11
          8000 fc - 1/500 @ f16
          8000 fc - 1/250 @ f22
     If your camera does not set lower than an ISO 200, set it to the 200 and double the footcandles.

Using a photographers hand held light meter:
     Set the light meter to an ASA or ISO to 100
     Make sure the the white cap is covering the meter for ambient light only
     Have the meter pointing up toward the light source and then take the reading
     Once the accurate reading is set, the EV numbers will indicate the footcandles equivilent:
          EV 10 - 168 fc
          EV 10.5 - 336 fc
          EV 11 - 478 fc
          EV 11.5 - 673 fc
          EV 12 - 951 fc
          EV 12.5 - 1345 fc
          EV 13 - 1903 fc
          EV 13.5 - 2601 fc
          EV 14 - 3805 fc
          EV 14.5 - 5382 fc
          EV 15 - 7611 fc
          EV 15.5 - 10763 fc

Your light source, your hand and a sheet of white paper:
     Place a sheet of white paper in the area that you wish to place a plant
     Place your hand twelve inches above the white paper with the light source above
     Looking at what happens to the shadow will determine the type of light you have:
          A very distinctive shadow exists with sharp edges: Vandaceous type light (5500 - 8000 fc)
          The shadow has softened greatly, edges are soft: Cattleya type light (1200 - 5500 fc)
          There is NO shadow at all, appears overall muddy: Phalaenopsis light (150 - 1200 fc)

Be sure to keep an eye on the seasonal position of the sun.  It is highest in the sky with short shadows during the summer (June 21st the longest day) while the sun is lowest in the sky with extremely long shadows during the winter (December 21st the shortest day).    


1 comment:

  1. Hi,

    For those with iPhones, there are some light meter apps, for example Pocket Light Meter, which is free from iTunes:




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