FOOT-CANDLES: Conversion Table

Orchid Doctor

by Robert M. [Bert] Hamilton (Compiler)

Originally published in The Orchid Doctor in 1980 and 1988

Posted by Sys Admin almost 4 years ago.

Article Blog   Article Index
Using a Weston light metre and a sheet of white matte cardboard, take exposure readings and rate them with foot-candles of light 16(6400), 15(3200), 14(1600), 13(800), 12(400), 11(200) etc. down to 4(1.6); the average for orchids is 14(1600); bright daylight with overhead sun is 10,000fc (England). OR-22
Share on Social Media:  
Log in to Add a Comment

More The Orchid Doctor Articles under the Heading Foot-candles

Foot-candles Comments
FOOT-CANDLES: Fc Rating Meaning One foot-candle equals the light emitted by one candle one foot away; expressed ratings are measured at noon Standard Time on a clear day; the maximum amount would be recorded around June 21 and the minimum December 21 in North America; a June 21 reading of 3950 fc. means a range of 2000 0 4000 for the year. A85-332 0
FOOT-CANDLES: Interpretation of the Meaning The recommended foot-candles of light for a species means the direct or incident light. A64-975 0
FOOT-CANDLES: Light Intensity Required by Plants Cattleyas:2500-3500; dendrobiums: 1500-2500; miltonias: 800-1200; odontoglossums:800-1000; phalaenopsis: 800-1200. 0R81-112 0
FOOT-CANDLES: Meaning The amount of light emitted by a burning candle one foot away; 500fc. is about enough to read a newspaper; a clear day in June (in Maine) would be 12,000. A86-814 0
FOOT-CANDLES: Minimum Amount Required to Affect Flowering This has not been determined; it is generally assumed that more than two fc. of light intensity is required to delay flower initiation by orchids; most commercial growers use lOfc. or more. A67-45 0
FOOT-CANDLES: Optimums For cattleyas the range is 2400 to 3600, for phalaenopsis it is 1500 to 1800. A86-815 0
FOOT-CANDLES: Outdoors, in Alberta During the summer there are about ll,000fc.; during winter between 4,500 and 6,000fc. A60-770 0
FOOT-CANDLES READING: By Means of Photographic Light Meter (weston Master) Read the light reflected from the surface of white blotting or type-writing paper without light from any other source; multiply the meter reading by four. A67-415; A74-34; Sekonic meter. A68-431 0
FOOT-CANDLES READING: Gro-lux Fluorescent Tubes Multiply foot-candles by 2.18 for correct fc. reading under Gro-Lux when using photo-exposure meter readings under normal light. OD70-242 0
FOOT-CANDLES READING: Using a Built-in Light Meter in a Camera Set the speed dial at ASA25 and the shutter speed at 1/60; aim camera at center of sheet of paper eight inches by eleven, eight inches distant; the lens opening (f-stop) is adjusted until the meter shows correct exposure; if lens opening is f/2 illumination is about 40fc.; f2.8 is 75fc.; f/4 is 150fc.; f5/6 is 300fc; f/8 is 600fc; f/11 is l,200fc.; f/16 is 2,400fc.; all figures approximate. A78-408 0
FOOT-CANDLES READING: Using Exposure Meter Set ASA at 10 and exposure at 1/100 second; hold the meter pointing at the center of clean white surface as closely as the smallest diameter of the surface(such as paper) casting no shadow and read: f/3.5 is 400fc.; f/4 is 500fc.; f/4.5 is 650fc; f/5 is 800fc; f/5.6 is l,000fc; f6.3 is l,300fc.; f/7 is l,600fc.; f/8 is 2,000fc; f/9 is 2,400; f/11 is 4,000fc. ; f/12.7 is 5,200fc; f/16 is 6,400fc. A62-105+; A69-1003; A75-680 0
FOOT-CANDLES READING: Using Photographic Equipment Use the meter on the camera; point latter at center of sizeable white surface without casting a shadow; set ASA at 10.3 and the shutter at 1/100 second and read: f/3.4 is 400fc.; f/4 is 500fc.; f4.5 is 650fc.; f/5 is 800fc f/5.6 l,OOOfc.; f/6.3 is l,300fc. ; f/8 is 2,000 fc; f/10 is 3,200fc; f/11 is 4,000fc; fl2.7 is 5,200fc; f/16 is 6,400fc; A65-244; A74-896; OR76-360 0
FOOT-CANDLES READING: With Photographic Light Meter Meters can be bought for reading foot-candles; with a Weston photographic meter convert to fc. by measuring light reflected from a piece of white matte paper and multiply the light value by four. A73-1081 0
FOOT-CANDLES: Requirements A sodium vapor lamp illuminated all night 100ft. away from cymbidiums in a greenhouse may not affect their flowering because they are temperature-responders; but plants requiring short days will not flower. A86-815 0
FOOT-CANDLES: Requirements for Main Types Cattleyas/laelias 3,000-3,500; cymbidiums 3,000; dendrobiums 3,000-3,500; odontoglossums 2,000+; oncidiums 2,500+; paphiopedilums 800-1,300; phalaenopsis 1,500-2,000; vandas and allied 3,500-4,000. OR76-360In summer: cattleyas 2,400-3,600; cymbidiums full sun; phalaenopsis 1,200-1,500; in winter: no shade generally for cattleyas and cymbidiums; if winters are partly sunny some shade is required by phalaenopsis and paphiopedilums. A61-734; OD73-198 0
FOOT-CANDLES: Requirements for Some Types Epidendrums like 3,600, and some will stand full sun; laelias like 2,400 to 3,600. A61-982 0

New Topics

  1. Robert H. Findlay asked question sideways images in category Site Navigation
  2. Khanh tran asked question Arranges Elro in category General Discussion
  3. John Small asked question Which is correct? in category General Discussion
  4. Jean Seymour asked question Can someone give me the name of this orchid? in category Phalaenopsis
  5. Debbie Chase asked question Help to Identify Orchid in category General Discussion

New Comments

  1. Carol Holdren commented on topic "sideways images" by Robert H. Findlay
  2. John Small commented on topic "Which is correct?" by John Small
  3. Mo Chen commented on member plant Holc. kimballianum by Mo Chen
  4. Carol Holdren commented on topic "Arranges Elro" by Khanh tran
  5. Fran Fassman commented on orchid E. Thomas Fennell
  6. Lauren Hutchison commented on topic "Unmatched Oncidium Alliance Orchid" by Colin Campbell
  7. Lauren Hutchison commented on member plant Oip. Celtic Sun 'Maya' by Dex W
  8. Lauren Hutchison commented on member plant Phalaenopsis Tristar by Lauren Hutchison
  9. Lauren Hutchison commented on member plant Phal. OX Golden Apple 'Honeycrisp' by William Gorski
  10. Debbie Chase commented on topic "Help to Identify Orchid " by Debbie Chase
  11. Tien Pham commented on member plant V. Yip Sum Wah 'Flame' by Tanya Lam
  12. Carol Holdren commented on topic "Can someone give me the name of this orchid?" by Jean Seymour
  13. Carol Holdren commented on member plant Spathoglotis plicata (Ground Orchid) by Frances LaVigne
  14. Frances LaVigne commented on member plant Grt. Rosy Jewel var. alba by Frances LaVigne
  15. Barry Mellefont commented on article "ANTS: Nesting Between Osmunda and Bark Slab Requires Control Safe for Visiting Hummingbirds" by Robert M. [Bert] Hamilton (Compiler)
  16. Carol Holdren commented on member plant Bc. Jairak Kiku 'Jairak kiku' by Frances LaVigne
  17. Frances LaVigne commented on member plant C. purpurata var. (flammea x sanguinea) by Carol Holdren
  18. Frances LaVigne commented on member plant Ascda. Kulwadee Fragrance by Frances LaVigne
  19. Melvin Waki commented on member plant Hwra. Lava Burst by Jeanne M Uzar
  20. Carol Holdren commented on member plant Den. Ruth Chun's Gemini by Melvin Waki