OTF lumens

So I’ve always liked knowing the OTF lumens of my lights but those numbers are not always readily available. What I have found though is most people agree OTF lumens is about 70% of the emitter lumens.

So right now I have a xintd c8 ran at the typical 2.8amps which equates to about 850lm at the emitter. So this, I assume would translate to about 600 OTF?

With my fenix lights, which are ansi rated, I believe those numbers are OTF. So my 860 lumen tk41, is 860 lumens correct?

Considering my slight obsession with accurate values, I might look into building an IS of some sort in the future.

Yup, ANSI lumens are OTF lumens I believe. Measured after a specific time too to accommodate for the output droop due to heating.

70% sounds right, except smooth reflectors will have higher outputs compared to orange peel and AR coated lenses will have slightly higher outputs as well.