Clarification for Phalaenopsis Shade Requirements

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There are a lot of used photographic light meters available on eBay. Search on
PHOTOGRAPHIC+LIGHT+METER

Many work on the photoelectric principle. The more photons striking a silicon semiconductor target the more electricity generated, which is translated to light flux. The smaller ones don't need batteries; they operate on the electricity generated from light striking the device.

An engineer friend found some used Gossen Panalux professional light meters on eBay a few years back for $20. You can point this one at the sun without damage.



This was a $3,000 instrument when new. You can still buy one but they're a little more than $20 now. Search eBay for GOSSEN+PANLUX+ELECTRONIC+LUXMETER