How can I use a camera light meter to guestimate lumens?

[fire-stick]

OK, I have digital SLR camera and I want to use it to guestimate lumens of one of my spotlights...

I have a P3D that has pretty good regulation at a steady 125 lumens.

If my camera says my spotlight reads 3 stops brighter than my P3D would it be safe to say that my spotlight is 1000 lumens; (or 8 times brighter?)

Thank you

Scott

 

[TedTheLed]

all factors being measured equally, then yes.

 

[gadget_lover]

This sort of works, but be aware that lumens = ALL the light that's emitted, not just the hot spot. An integration sphere tries to reflect all the light back to a single point AND it avoids a direct view of the light source.

A closer approximation is to point the light at a white wall 3 feet or so from the light, take the reading, then place the second light in exactly the same spot and do it again. It still won't be accurate, and still has to take into account the possibility that your meter is taking a spot reading, but it would give you a relative measurement.

Daniel