Mysterious coloration on Cattleya

[Britton Flash]

This coloration has recently appeared on my Cattleya hybrid. It was outside all summer and did great other than one instance of sunburn. This appeared about two weeks ago; it started minor and increased to about this point and stopped. The temperatures dropped somewhat, nighttimes down to roughly the high fifties (13-15 degreeC), but these temperatures certainly aren't too extreme for this plant(are they?). For the record, all the plants are inside for the season, I just finished setting up for the long winter.

Speaking of, I have been doing some research on lighting, and came across a conversion formula for lumens to footcandles at a given distance involving the lumens, distance, and angle. Does anyone have experience with this formula that can attest to its reliability for T5 and T8 lighting(tested it with a meter)? I am trying to be more precise with the distance I am putting between the source and plant.

Sorry for the regurgitation. Might as well get it all out at once eh?

[dendro king]

this has occured on a few of mine too. it has never seemed to harm them and is basicly like a freckle on a person.

[RosieC]

I got this on mine this year. I assumed it was a sun-tab (rather than sun-burn) as I know other orchids that go red in the sun without burning.

[DavidCampen]

Originally Posted by Britton Flash

... I have been doing some research on lighting, and came across a conversion formula for lumens to footcandles at a given distance involving the lumens, distance, and angle. Does anyone have experience with this formula that can attest to its reliability for T5 and T8 lighting(tested it with a meter)? I am trying to be more precise with the distance I am putting between the source and plant.

The best and most accurate thing to do is buy a light meter so you can make your own footcandle measurements. Here is the one I use, $35 from Amazon:
http://www.amazon.com/Mastech-Digita...ds=light+meter