Thanks so much, were you the one who posted some reviews with that big white ball and the lux meter? or someone else? I saw some reviews done with that in the review section before and those test were quite insane!
Does it matter if the room is pitch black or not when testing these things as well?
How come some test with "ceiling bounce"? what is the difference?
You're very welcome! Unfortunately, I don't have an integrating sphere or a nice lux meter, though there are many members here who have access to one (or have created their own..i.e. Selfbuilt).
Regarding ambient lighting, it is most desired to have as little ambient lighting as possible for the most accurate results, as a little bit of outside light MAY disrupt a reading especially on a homemade integrating sphere.
A ceiling bounce is VERY useful for gauging the true amount of light coming out of the flashlight. When you stare at the hotspot, it's very hard to determine exactly how much light is coming out, because of the varying hotspot sizes/intensities, as well as the spill. Many people don't realize that the spill counts as part of the lumen rating, because many times, the spill isn't noticeable compared to the long throwing hotspot. In a ceiling bounce, you can generally visualize the amount of light coming into the room. (you'd never look directly at a lightbulb in a lamp to see how bright it is, you'd look at the light bouncing around the room and how clearly you can see everything).
**note** you can also use a diffuser to gauge the general light output of a light, but there will be greater lumen loss than with a ceiling bounce as much of the light is trapped in the diffuser. Again with this test, try not to look at the diffuser on a light because it'll pretty much be the same as staring down the barrel of an light in operation.