Yes, it is indeed possible that 47s is overly conservative, just as it is possible ZL is overly exaggerating. I do mention the scale difference, and triangulation to SB in the above linked thread. But even adjusting for the scale difference doesn’t account for all the exaggeration.
So which is the correct scale (which I find around ~30% different)? I’ll borrow a quote from Selfbuilt’s review site:
“In any case, I still make no claim to the accurate lumen estimate accuracy. But the runtime graphs remain a well-calibrated and internally-consistent relative set of results from my testing, using only new batteries properly examined for relative performance.”
From my perspective, as a moonlight mode collector, I have lights from 47s, ET, TN and ZL and the first three manufacturers all calibrate spot on to the same lumen scale, while ZL is out in left field. And this triangulates with Selfbuilt - his reviews of the QAA2X, D25 Clicky series, and TN Neutron 1A, all show these lights to be ~100 lumens “under-rated.” There are plenty of other manufacturers on either side of these scales.
Now, if I were in Selfbuilt’s shoes, I would absolutely adopt a liberal lumen scale, since it is far, far easier to deliver good news, and great news, than it is to deliver any bad news.
The important point is that the SC52 is not nearly twice as bright, or twice as efficient, as a comparison of the listed specs suggest, especially among the direct sub-lumen competitors, partly because of the lumen scale difference, and partly for “other” reasons.
