Re: Rick Trent laser kits
Even if the lens focus ring were to reduce output (very unlikely as the beam is already collimated) it wouldn't reduce it by 500 mW...So I doubt that has any real relevance, restricting the beam before the lens however would be much more of an issue!
@awillis You could mark the position for the metering, just to be a little more accurate with the distance and angle, and try to make sure the dot on the sensor has an identical size with each lens. Also Daguin said, let the laser reach thermal equilibrium before each measurement, but again the run times you had wouldn't necessarily warrant that.
Anyway nice test and thanks for checking the lens for us! +1