On Wednesday, February 21, 2018 at 4:14:21 PM UTC, Jeff Liebermann wrote:
On Wed, 21 Feb 2018 01:30:26 -0800 (PST), Andre Jute
wrote:

On Wednesday, February 21, 2018 at 8:21:42 AM UTC, Jeff Liebermann wrote:
On Tue, 20 Feb 2018 20:31:59 -0800 (PST), Andre Jute
wrote:

Sigh. I see that you haven't been reading my rants. That's the exact
model that I've recommended in at least three of my previous rants on
the topic. Also available on eBay and Amazon.
https://www.ebay.com/itm/222318701790
or search for "lux meter".

The more sources the better, then.

I have 2 other Lux meters. Both have removable sensor "pucks" which
allegedly make measurements easier. I've compared readings between
the three meters and find that they are all fairly close to each
other. I don't have a calibrated source, so I can't determine their
accuracy. The UNI-T UT383 above is the most useful because it's the
only one that has a peak reading feature. I mark the diameter of my
one square meter circle on the wall, turn on the test flashlight or
headlight, and walk towards the wall until the spot has the same
diameter. I then turn off the light, and the highest reading remains
on the display. Very handy for doing measurements without an
assistant.

If you want better accuracy, measure the hot spot in the center and
the brightness at the edges. I usually give it 33% above the edge
value, although 50% is probably close enough.

I like your DIY calibration test, though.

You might want to measure your various lights and headlights and see
how they compare with the published specs. If enough people do that,
maybe we can see an end to inflated lumens specs. I measured about 15
assorted lights and flashlights, but nobody seemed interested.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Even at such an attractive price, I'm not buying the meter, Jeff. For health reasons, I no longer go for those middle watches of the night rides, as no one will go with me and it's stupid for me to ride alone on totally empty lanes. So I have nothing to measure for.

In any event, by subjective measurement a la Roger's post, I judge I already have what on balance I consider BUMM's best lamp, the first series Cyo R (I also have reflectorless version but it isn't as good in lanes as the R, and I have the Fly-E with supposedly the same optics but with a very nasty hotspot), so I'm not even in the market for new lamps.

Andre Jute
It's a dull life if you can't even think of a tool you want