SIX thousand and FIVE hundred lumens !!!!!!!!!!

On Fri, 05 Oct 2018 15:38:49 -0700, wrote:

On Friday, October 5, 2018 at 11:22:00 AM UTC-5, jbeattie wrote:
On Friday, October 5, 2018 at 7:31:57 AM UTC-7, Joerg wrote:

Yet strangely, it jibes with that of our government folks. Why do you
think they mandate DRL on motorcycles?

And yet motorcycles are the one category of MVs in Oregon with
increasing fatality rates. e.g.
http://www.eastoregonian.com/eo/loca...al-motorcycle-
crashes-spiking-this-year

-- Jay Beattie.

But are increasing motorcycle fatalities due to 1. Motorcycles just
being more dangerous, smaller, harder to see, or 2. Stupid, careless,
reckless drivers of motorcycles, or 3. Fatal in crashes because the
drivers are manly men who choose to NOT wear helmets?

And most probably have a strong preference for "cool" black leather
jackets rather than the more visible day-glo orange/yellow/lime that
would improve their visibility.

On Thu, 04 Oct 2018 19:26:11 +0200, Emanuel Berg
wrote:

Jeff Liebermann wrote:

OK, so FL 1 is the "ANSI FL1 Standard" ("FL"
is "flashlight", I take it) and cd is
"candela". I suppose one has to read the
article [1] to learn what sense to make of
the 400cd specification.

[1] http://www.led-resource.com/ansi-fl1-standard/

Maybe reading the definitions of candelas,
lux, and lumens might help

I don't think so

I selected basic, short, simple, easy to understand web pages.
If you can't, or won't, understand those, there is no hope. It
doesn't get much simpler than this:
https://www.jwspeaker.com/blog/lighting-terminology/

https://blog.1000bulbs.com/home/whats-the-difference-between-candela-lux-and-lumens
https://www.knivesandtools.com/en/ct/torches-lux-candela-lumen.htm
There are calculators for converting between
these. Be sure to read about "solid angles".

OK, I read the two web pages! (There is nothing
on solid angles what I could see.)

I was in a rush to leave for a service call and add the solid angle
note without a link because I assumed that you would search for the
term using Google.
http://lmgtfy.com/?q=solid+angle
You'll need to understand solid angles and steradians if you really
want to measure candelas.

What *I think* I understood is that

LUX: lux is describing how bright the object
will be, or how big an area (floor or wall) you
can enlight, by pointing the flashlight at it.

1 lux = 1 lumen per square meter.
If you have a flashlight that produces 1 lumen, and you illuminate a
vertical wall or something similar so that the light spot on the wall
is 1 square meter in area, a light meter will display a luminous
intensity of 1 lux.

LUMEN: lumen is how much light that comes from
the light source, only this doesn't take into
account if and how the light is obstructed or
enforced/directed, e.g. because of the
construction of the lamp, what lens there
is and where, etc.

Yeah, something like that except that you threw in a bunch of
irrelevant rubbish. If you take a light source, ANY light source, and
capture ALL the light it produces, in any direction, you have lumens.

CANDELA: candela takes into account
obstructions (various blockings of the light)

Wrong. Wrong. Obstructions are not involved in any of the
calculations or units of measure.

but also the enforcing of it thru a lens.

Wrong. No lenses are involved in any of the units of measure.

This means that candela is a good unit to
determine how far away the light will actually
be visible, for example if you waive it to the
sea from the beach of a deserted island...

Wrong. All these measurements involve visibility in terms of the
color sensitivity of the human eye, but have nothing to do with the
visitibily of a reflected light (sand or ocean).

Candelas uses the solid angle that I previously recommend that you
study and includes the color sensitivity curve of the human eye. It
would not do for a lamp to be bright at a color that the eye cannot
see. The usual choice of color to make this measurement is 555
nanometers or green, which is where the human eye is most sensitive.
This is a problem for white LED lights, which produce blue and yellow
light, but no green. Same with LED grow lights that produce no green.
In general, candelas have little use in bicycle lighting except by
marketing to confuse the buyers. Stay with lux and lumens.

Candelas are much like lumens, except that candelas are for spot
illuminators like flashlights and bicycle lights that produce a spot.
Lumens are non-directional, while candelas are directional.

For bike applications, it seems for commuting
in a well-lit city with traffic, you'd want
candela, for MTB you'd want lux, and for
touring, you'd want a combination

No. Frank explained the basic requirements quite well. All the
various specs are compromises. You can have a really bright (high
lux) light, but the radiation angle will small and only illuminate a
distant spot. You can have a huge number of lumens, but most of the
light will be wasted blinding the rider, oncoming traffic, and objects
that are not along your riding path. You can have an "focused" light,
that will produce a hot spot that will trash your night vision. What
you really want is an even light intensity across the area that is
illuminated. That's not easy when the road is not flat and you're
using a single point source of LED light.


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

Jeff Liebermann wrote:

I selected basic, short, simple, easy to
understand web pages. If you can't, or won't,
understand those, there is no hope.
It doesn't get much simpler than this:
https://www.jwspeaker.com/blog/lighting-terminology/

OK, so lux is how bright an object or surface
will be if you use the given light source to
illuminate the object or surface. Specifically,
1 lux is the amount of light distributed over
1 square meter if you stand 1 meter away with
1 light source of 1 lumen.

Lumen is how much light is produced in all
directions. It is "measured using a photometric
testing device".

Candela is how much light is produced in one
direction. Specifically, it is the intensity of
the light that travels from the light source at
555 nanometers, which is green, and into the
human eye.

Did I ace it this time?

--
underground experts united
http://user.it.uu.se/~embe8573

Jeff Liebermann wrote:

I was in a rush to leave for a service call
and add the solid angle note without a link
because I assumed that you would search for
the term using Google.
http://lmgtfy.com/?q=solid+angle

Jeff, did you ever considered a career as
a teacher? Your class could be called "teach
your profession and be frustrated when people
don't immediately understand it".

--
underground experts united
http://user.it.uu.se/~embe8573

On 2018-10-05 08:33, Radey Shouman wrote:
Joerg writes:

On 2018-10-04 18:13, Radey Shouman wrote:
Joerg writes:

On 2018-10-04 14:43, Radey Shouman wrote:
Frank Krygowski writes:

On 10/4/2018 2:12 PM, Joerg wrote:
On 2018-10-04 10:40, Frank Krygowski wrote:
On 10/4/2018 11:02 AM, Joerg wrote:
On 2018-10-01 15:14, wrote:
http://reviews.mtbr.com/magicshine-l...2018-interbike

The beloved Magicshine brings us what we finally need in bike lights.
Thanks to all the gods. 6500 lumens! I think you can have either
5000 or 1500 or all 6500 lumens. Thankfully now we will not only be
able to blind everyone else on the road or trail, but we can now
cause their eyeballs to burst into flames and maybe hopefully their
heads will also explode. Yeah!!!!!!


This one for their rear light is weird, quote "A sleep mode is
triggered after one minute of inaction to save power, any vibration
will immediately re-activate the unit".

So the light will go out while waiting at an intersection? Really?
Nobody raised their hand during the design review? Was there even a
design review?

First, their definition of "sleep mode" may not be "goes out." It could,
I suppose, just become much dimmer. In any case, it would be easy enough
to jiggle the bike a bit to turn it back on.


Not very smart on the part of the design engineers.


But it's probably not necessary. Ohio law specifically permits lights
that go out when the bike is stationary, ...


Not a smart decision by the lawmakers.


... and there's never been a report
of a death or serious injury caused by that feature.


Grandpa drove without a seat belt all his life and never go hurt, so ...

Grandpa also rode his bicycle without a six foot tall safety flag, a
siren, a bell constantly and automatically ringing every time he
moved, pads on his knees, pads on his elbows, body armor protecting
his spine. Why are you not using all those measures?

(Actually, maybe you are. With you, we never know.)



BTW, it even happens from the front, even by police officers:

https://fox2now.com/2018/07/30/polic...hone-in-video/


Nothing can replace bright light other than even brighter
lights. Which both of my bikes have.

Joerg, you're the master of the worldwide search for the vanishingly
rare exception. That is NOT a common crash type, as any dispassionate
search of the literature would shoe. And you have no evidence that
your daytime headlight would have prevented it.

Looks like the video has been taken down, at least fox2now.com can't
find it.


Works fine here.

Works for me now, no more "video unavailable".


... The accident happened in broad daylight, no vehicles save the
cop SUV and the cyclist visible for miles, cyclist waiting at an
intersection, I think for a stop sign. Total f*up on the part of the
cop, who was more or less apologetic. A daytime running light would not
have helped.


Not true. I clearly found that drivers notice me much better with
bright lights. Even in the corner of their eyes is enough because it
"distracts" them in a good way. All it takes is noticing a cyclist a
second or two earlier and a collision can be avoided.

Seriously? The cop would have looked up from his phone if only the
cyclist had had a light? Sounds like magic.


Easy to try. While distracted with some chore in your home, have
someone walk towards you pointing a bright but not blinding LED
flashlight. It works. A human eye is not insensitive in the directions
where one does not look, just less sensitive. The "muffling effect"
needs to be overcome and intense light is just about the only method
to achieve that.

This wasn't inside, it was outside in bright daylight, looked like
hardly a cloud in the sky.


Try this in daylight. It works.


... A really bright light is required to make much difference
in that case.


Bingo! Now you know why I have bright lights on my bikes. I experienced
it again yesterday. I had to ride through city streets for many miles,
partially at max speed. With the light fully on nobody cut into my path.
Without lights that is different.


Other clue: You are driving a car, looking ahead into traffic as you
are supposed to do. The dashboard becomes largely unnoticed except for
the occasional glance at the speedometer. However, when the yellow
check engine light, the red oil pressure light, the overtemp light or
the low fuel light comes on it is immediately noticed. Same if someone
behind you flashes their headlights even while you aren't looking into
the rear view mirror.

That only happens if you have the habit, perhaps not completely
conscious, of scanning the dashboard. How do you know it's "immediate"?
You notice it when you notice it, and if it's 10 seconds after the event
that's not a big problem, unlike the case for traffic on the road.


If bright enough or if a less bright light in flashing mode I see that
immediately. An airline pilot could even lose his license if he didn't.


Yet another one: Think about the reason why approaching emergency
vehicles have very bright flashing lights.

In my world they usually turn on their sirens when approaching busy
intersections, especially if they intend to blow the light.


When they approach from far up front or behind I am pulled over to the
shoulder and stopped before they even get there, as is required by our
law. Same for the drivers in front and behind me. The siren is only
heard way later and often too late.

IMHO if someone only notices an approaching fast police cruiser when
they hear the siren they should not have a driver's license.


There is a reason why DRL have been mandatory on US motorcycles for a
long time.



--
Regards, Joerg

http://www.analogconsultants.com/

On 2018-10-05 09:51, jbeattie wrote:
On Friday, October 5, 2018 at 7:28:43 AM UTC-7, Joerg wrote:
On 2018-10-04 18:13, Radey Shouman wrote:
Joerg writes:

On 2018-10-04 14:43, Radey Shouman wrote:

[...]


... The accident happened in broad daylight, no vehicles save
the cop SUV and the cyclist visible for miles, cyclist
waiting at an intersection, I think for a stop sign. Total
f*up on the part of the cop, who was more or less apologetic.
A daytime running light would not have helped.


Not true. I clearly found that drivers notice me much better
with bright lights. Even in the corner of their eyes is enough
because it "distracts" them in a good way. All it takes is
noticing a cyclist a second or two earlier and a collision can
be avoided.

Seriously? The cop would have looked up from his phone if only
the cyclist had had a light? Sounds like magic.


Easy to try. While distracted with some chore in your home, have
someone walk towards you pointing a bright but not blinding LED
flashlight. It works. A human eye is not insensitive in the
directions where one does not look, just less sensitive. The
"muffling effect" needs to be overcome and intense light is just
about the only method to achieve that.

Other clue: You are driving a car, looking ahead into traffic as
you are supposed to do. The dashboard becomes largely unnoticed
except for the occasional glance at the speedometer. However, when
the yellow check engine light, the red oil pressure light, the
overtemp light or the low fuel light comes on it is immediately
noticed. Same if someone behind you flashes their headlights even
while you aren't looking into the rear view mirror.

Yet another one: Think about the reason why approaching emergency
vehicles have very bright flashing lights.

Now imagine all of these riders with lights and sirens:
https://d3n8a8pro7vhmx.cloudfront.ne...png?1428427634

This is the daily commuter traffic into downtown. Now put all those
people on the two-way cycle track on my way into work.
https://bikeportland.org/wp-content/...ansit-bend.jpg
Now live with that.


As I've written several times, bright lights are not needed on bike
paths. I turn them off there during the day. They are also not needed
when there are lots of cyclists (safety in numbers). It's different out
here, this is not Portland, Amsterdam or Copenhagen.


Solid white lights in bright sunshine are almost universally
irrelevant and annoying to other cyclists and drivers.


No, they are not. Why do you think motorcycles have mandatory DRL? Just
for fun?


... I see jerseys
and body shape long before I register the light.


That is totally contrary to my experience and that of just about anyone
I know.


... And BTW, having
driven ambulance for six years, I spent plenty of time sitting behind
cars with my deafening Federal Q2B pegged before the dopey driver
turned down the music and realized I was sitting there -- and then he
freaks out, hits the gas, goes into the intersection and gets
whacked. It can be a sh** show. Whatever giant light, siren,
calliope, marching band you claim will save your life can only make a
marginal improvement and proving that margin is hard if not
impossible, and a blinding light can cause accidents or at least
upset.


That driver shouldn't have a license.


What will really reduce accidents is being a good rider and knowing
how to ride in traffic and with entering or exiting traffic.


That's the problem. A lot of car drivers do not fall into that category
and that is beyond my influence. What I can influence is how my ship is
lit, so I do that.


... A DRL
may help, but it is certainly not magical and is irrelevant in many
situations. Lights are critical at night, obviously -- but mega
lights are totally unnecessary on city streets in dry weather. What
is "enough" at night varies depending on terrain, conditions, etc.,
but whatever is enough, it can't be blinding people.


Again, my experience is very much contrary to that. And my experience
seems to jibe with what national safety boards have found out about
motorcycle lighting.

--
Regards, Joerg

http://www.analogconsultants.com/

On 2018-10-05 08:48, Frank Krygowski wrote:
On 10/5/2018 10:32 AM, Joerg wrote:
On 2018-10-04 20:34, Frank Krygowski wrote:
On 10/4/2018 3:34 PM, Joerg wrote:
On 2018-10-04 12:18, jbeattie wrote:

It takes very little light to be conspicuous at night, and it takes
no additional light to be conspicuous during the day -- assuming
broad daylight without cloud cover or other low-light condition.


My experience is clearly different.

Your experiences are almost always unique, not just different.


Yet strangely, it jibes with that of our government folks. Why do you
think they mandate DRL on motorcycles?

Joerg, you're arguing against yourself (again)!

Please note, the government does NOT mandate daytime running lights on
bicycles!


They do on motorcycles, they don't care much about cyclists as we all know.

--
Regards, Joerg

http://www.analogconsultants.com/

On 2018-10-05 09:21, jbeattie wrote:
On Friday, October 5, 2018 at 7:31:57 AM UTC-7, Joerg wrote:
On 2018-10-04 20:34, Frank Krygowski wrote:
On 10/4/2018 3:34 PM, Joerg wrote:
On 2018-10-04 12:18, jbeattie wrote:

It takes very little light to be conspicuous at night, and it takes
no additional light to be conspicuous during the day -- assuming
broad daylight without cloud cover or other low-light condition.


My experience is clearly different.

Your experiences are almost always unique, not just different.


Yet strangely, it jibes with that of our government folks. Why do you
think they mandate DRL on motorcycles?

And yet motorcycles are the one category of MVs in Oregon with increasing fatality rates. e.g. http://www.eastoregonian.com/eo/loca...king-this-year


You of all people, having been an amulance driver, should know the
reason. The reason is this behavior:

https://www.youtube.com/watch?v=ZkWWVryT1UE

That is the road where I was almost clipped by a motorcyclist. He didn't
anticipate that there could be a mountain bike in a right turn, hugged
the curve at high speed and ... "GAAAH!". I heard his engine screaming
but didn't have anywhere to go because of a wall of rock to my right. He
needed the full oncoming lane to get the situation somewhat under
control. Imagine what would have happened if there'd been oncoming traffic.

--
Regards, Joerg

http://www.analogconsultants.com/

On 10/6/2018 11:11 AM, Joerg wrote:
On 2018-10-05 09:51, jbeattie wrote:

Â*Â*Â* ... I see jerseys
and body shape long before I register the light.


That is totally contrary to my experience and that of just about anyone
I know.

I _very_ much doubt you have examined this impartially.

I've done thousands of miles of driving SAG for invitational bike rides.
I've observed tens of thousands of cyclists. In all but a microscopic
percentage of cases, the cyclist has been visible before a daytime light
is visible.

Since this popped up as the newest "Danger! Danger!" craze a few years
ago, I've been observing cyclists on the road. I can recall only one
time that I saw the light before I saw the daytime cyclist, and that was
a case of an illegal light. A woman cyclist was riding a two-lane
highway and she had some mega-bright white headlight facing backwards.
It _was_ bright enough to be very, very irritating if not blinding. And
it was illegal because white lights to the rear are forbidden in this
state, except for "back up lights."

In every other case, it's been "There's a cyclist." And later "Oh, and
he's got a light on his bike."

And in that woman's case and every other case I've observed, daytime
lights have NOT been significant in preventing a crash or a near miss.

Why on earth does someone riding a two lane highway with no
intersections think they have to have a white light facing forward? It's
a paranoia.

--
- Frank Krygowski

On 10/5/2018 6:38 PM, wrote:
On Friday, October 5, 2018 at 11:22:00 AM UTC-5, jbeattie wrote:
On Friday, October 5, 2018 at 7:31:57 AM UTC-7, Joerg wrote:

Yet strangely, it jibes with that of our government folks. Why do you
think they mandate DRL on motorcycles?

And yet motorcycles are the one category of MVs in Oregon with increasing fatality rates. e.g. http://www.eastoregonian.com/eo/loca...king-this-year

-- Jay Beattie.

But are increasing motorcycle fatalities due to 1. Motorcycles just being more dangerous, smaller, harder to see, or 2. Stupid, careless, reckless drivers of motorcycles, or 3. Fatal in crashes because the drivers are manly men who choose to NOT wear helmets?


If you're going to ascribe increasing motocycle fatalities to any of
those factors, you'll have to show how the relevant factor has increased
over recent time. I don't believe they have.

--
- Frank Krygowski