Wuzzat?

Any photographers out there?

I may have a method for using a digital camera as a light meter.

White paper at 70 lux reflects 61% of the incident light.

Set your camera at ISO100 and take a picture of white paper in the incident light level to be measured with your existing lighting in kitchen, family room, whatever.

Convert your shutter speed and f stop of that photo to an exposure value.
http://en.wikipedia.org/wiki/Exposure_value

Convert your exposure value to lux
http://www.intl-lighttech.com/support/calculator

Multiply by 1/0.61.

Upgrade or downgrade your lighting (watts, lumens) to suit.
http://www.personal.psu.edu/users/a/s/asp5045/roomcalclivingroom.htm


Will this work?

speedy petey

Honestly not sure.

I am a hardcore amateur photographer. I have to say, the light meter app on my phone seems like MUCH less work.

Wuzzat?

I don't have a cell phone (or ATM card or credit card).
Where I live many people are addicted to these gadgets. I saw one guy take one bite of his meal, then check his gadget, then another bite. . .



For me I guess the fun is in doing it myself from bits and pieces of what I already have.

My test case will be two floodlights, both ~600 lumens & 120v, one from the market and the other from Grainger that is supposed to last 20,000 hours.
The long life bulb is noticeably dimmer.

I won't even need the white paper, just two photos of two couch cushions that these lights are over.

Then I guess I should check that the beam angle for both bulbs is the same.