Minimum test for throw

Does your flashlight throw? Of course lasers are good for putting a very small amount of light on a subject at a distance. However my definition of throw amounts to putting a usable amount of light on a subject at distance. Once you answer the initial question of whether a light will throw or not, then you can get into how well does it throw.

My test covers both parts of the question - does it throw or not, and how well does it throw. I have a very easy pass/fail test. Will it turn off a street light or not. If it will, then it throws. Now we can get into the question of how well it throws.

From a short distance, how many seconds does it take to turn off the light (Mag 2c with Pilas and a 6v halogen bulb, and Ultra Stinger - 8 to 10 seconds; X990 - 1 second). Throw test part 2 - how far away from the the street light can you be and still turn off the light (X990 about half a block).

Given the fact that not all street light sensors are created equal, YMMV.

I'm confused by your test - you can easily turn off a streetlight with a green laser pointer. I do this all the time. It's great fun! When you hit the sensor, it's more or less instant.

I stand corrected. I just went outside and tried the green laser. You were right, but it is a pain in the butt trying to hit that sensor with a laser if your hands are as shakey as mine. It is also hard to type this with a large red dot where ever I look.

Okay lets limit the test to non-laser devices (i.e semi-white lights).

i wouldn't reccomend throwing your lights. it could eventually cause irreversible damage to the unit.

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just kidding. (haha?)

i don't think that's an accurate test for a couple reasons. 1) incandescent lights have an advantage over LED's when it comes to overcoming light pollution. it might only be a borderline difference in actual testing (around the zone where the incandescent hits the sensor, but the LED of equal lux gets washed out b4 it gets there), but it can make a difference.

2) your test is only an indication that it can throw as far as the sensor. if it takes 1000 lux minimum hitting the sensor to turn it off, then hey, your light throws 1000 lux. but that means any light with 1000 or more lux @ beam center will pass your test without giving an accurate image of how far the light actually throws. you might say "Well, it hit the sensor, she's good to go." but when you get out into the field, you might actually find yourself wishing you had more throw when you hear noises acrossed the clearing on the opposite tree-line.

3) it's based largely on opinion. i don't think a light with 1000 lux @ beam center is a particularly far throwing beam. move up to 1500-2000 lux @ beam center and you're getting somewhere.

so while the 1000 lux that turns the sensor off in your street light makes you happy, someone else might think that's not even half-way there.

if i really wanna test the throw on a light, i sneak onto the golf course to test my lights. nothing beats big signs with reflective tape in the corners in 25-yard increments, starting @ 25 yards. /ubbthreads/images/graemlins/grinser2.gif (don't tell anyone tho!)

i've tried to get my pops to loan me his 500 foot measuring tape, but he wont let me use it.

i'd like to make my own scaled-version of the golf course method @ a park down the street. in 25 FOOT increments instead of yards.

Hmmm, I think our street lights are controlled in another way, block by block.
I'm clueless as to where the main sensor is that turns on all blocks simultaniously (That's what happens here AFAIK), or, if there even is one... /ubbthreads/images/graemlins/icon3.gif It can just as well be a timer for all I know.
There is no way you can turn off a street light here with a lightsource.

Same here Bart, i believe they turn on by timer.

Streetlights 101: Multiple Choice Thanksgiving Quiz.

Question 1:

Where is the sensor on most streetlights?

1) On top of the pole.
2) At the bottom of the pole.
3) In the pole hole.
4) At the North Pole.
5) None of the above.

Where is the sensor, please??

[ QUOTE ]
BlindedByTheLite said:
1) incandescent lights have an advantage over LED's when it comes to overcoming light pollution. it might only be a borderline difference in actual testing (around the zone where the incandescent hits the sensor, but the LED of equal lux gets washed out b4 it gets there), but it can make a difference.


[/ QUOTE ]

There may be a difference to the human eye as far as incandescent versus LED beams go--particularly in the presence of ambient light--but there is no external physical phenomenon corresponding to "washing out." If a mechanical sensor is sensitive to lux only (independent of wavelength distribution), then an LED beam will be just as effective as an incandescent beam.

This assumes that the lux values are actually the same, though. More often than not, the incandescent beam will have a higher lux and will perform better outdoors for that reason.

[ QUOTE ]
sotto said:
Streetlights 101: Multiple Choice Thanksgiving Quiz.

Question 1:

Where is the sensor on most streetlights?

1) On top of the pole.
2) At the bottom of the pole.
3) In the pole hole.
4) At the North Pole.
5) None of the above.

Where is the sensor, please??

[/ QUOTE ]

Around here, I say the answer is either 1) depending on how you interpret that or 5) - the sensor is on top of the light fixture itself. You have to hit the sensor for a second or two. Not all of them seem to have sensors, or maybe I'm just a lousy shot...

Some guys in our astronomy club put their lasers on a tripod, with a constant on switch to keep nearby streetlights off while they are using their scopes. /ubbthreads/images/graemlins/grin.gif

[ QUOTE ]
BlindedByTheLite said:

2) your test is only an indication that it can throw as far as the sensor. if it takes 1000 lux minimum hitting the sensor to turn it off, then hey, your light throws 1000 lux. but that means any light with 1000 or more lux @ beam center will pass your test without giving an accurate image of how far the light actually throws. you might say "Well, it hit the sensor, she's good to go." but when you get out into the field, you might actually find yourself wishing you had more throw when you hear noises acrossed the clearing on the opposite tree-line.



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You failed to read part 2 of the test - "How far away from the street light can you be and still turn it off. Also the title of this thread is "minimum" test for throw. If the light won't even turn off a street light then it is not a thrower at all IMHO.

In answer to sotto's question - in my neighborhood the sensor is mounted on top of the actual light fixture.

JimH:

Thanks!

and MrBenchmark:

How long do the streetlights stay off? Would a red laser beam also work to shut the light off?

Unless you're in a rural area isn't it a dangerous practice?

Brightnorm

Brightnorm:

It's flashaholic self-defense IMHO. Around my house, it's getting so you can get a suntan at 2 a.m. /ubbthreads/images/graemlins/cool.gif

[ QUOTE ]
sotto said:
Brightnorm:

It's flashaholic self-defense IMHO. Around my house, it's getting so you can get a suntan at 2 a.m. /ubbthreads/images/graemlins/cool.gif

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Here, here !!! /ubbthreads/images/graemlins/Christo_pull_hair.gif

Yep I was just outside with my son and we were using Red lasers....2AA batts, Wavelength 670nm Max output <5 mW

Lights stay out for about 1 minute or so.

Its cool /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

A-hah! Law-scoffing agitators, are we???

[ QUOTE ]
asdalton said:
There may be a difference to the human eye as far as incandescent versus LED beams go--particularly in the presence of ambient light--but there is no external physical phenomenon corresponding to "washing out." If a mechanical sensor is sensitive to lux only (independent of wavelength distribution), then an LED beam will be just as effective as an incandescent beam.

This assumes that the lux values are actually the same, though. More often than not, the incandescent beam will have a higher lux and will perform better outdoors for that reason.

[/ QUOTE ]

Note that >80% of the energy emitted by an incandescent light is in the infra-red spectrum and that LEDs emit no IR. If the sensor is sensitive to IR, and I suspect that it is, this would explain why incandescents work better.

[ QUOTE ]
MR Bulk said:
A-hah! Law-scoffing agitators, are we???

[/ QUOTE ]

Oops..... /ubbthreads/images/graemlins/blush.gif Just wanted to see if it would work....don't plan to make a habit of it.

The laser is really for the dog...he loves to chase it around the house and yard at night.

Aloha,
Bill

[ QUOTE ]
Heath said:
[ QUOTE ]
asdalton said:
There may be a difference to the human eye as far as incandescent versus LED beams go--particularly in the presence of ambient light--but there is no external physical phenomenon corresponding to "washing out." If a mechanical sensor is sensitive to lux only (independent of wavelength distribution), then an LED beam will be just as effective as an incandescent beam.

This assumes that the lux values are actually the same, though. More often than not, the incandescent beam will have a higher lux and will perform better outdoors for that reason.

[/ QUOTE ]

Note that >80% of the energy emitted by an incandescent light is in the infra-red spectrum and that LEDs emit no IR. If the sensor is sensitive to IR, and I suspect that it is, this would explain why incandescents work better.

[/ QUOTE ]

True. Also, there is a physical phenomenon corresponding to this washing out, or there can be, and it also has to do with the differential output spectra of incan vs LED.

As Heath said, incans put out a lot more IR; they also are generally red-heavy, as we all know. LEDs tend to be blue heavy. Blue photons scatter off of fog, particulates, thermals, and pretty much any other kind of boundary much more easily than the red photons (which do more ray-like bending than particle-like scattering), and this is causing the washing out. This phenomenon is responsible for the blue sky, red sunsets, and the glare from a snowfield (glare is generally scattered non-directional blue).

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brightnorm said:
Unless you're in a rural area isn't it a dangerous practice?

Brightnorm

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Not really. I wouldn't do this near a freeway entrance / exit ramp, nor a busy intersection, but most other places are so massively overlit as to be ridiculous. Plus, cars have headlights... /ubbthreads/images/graemlins/wink.gif

Actually, sometimes the stray lighting from all the streetlights is what is dangerous. Consider how much of it is directed as glare into your eyes, and how much of it is directed upwards. The light directed upwards is completely wasted, and a real hazard to astronomers. The light directed into your eyes is hazardous to drivers - it does not help you see the roadway, it reduces your ability to see the roadway.

The light dome over the city of Dallas, where I live, is so large that I have to drive for about 100 miles to get someplace dark enough to actually see the stars. So, no, I don't think turning out a streetlight every now and then is all that dangerous - there's plenty of light around here, trust me!