2222 Post Giveaway... Now closed: we have a winner!

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totilde
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i love this kind of crap! thanks a lot

Mooooooo

BLightSam
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I don’t like crap.
Kudos to your 2000+ posts.

juhha
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fatboy
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Ya lux meter

likeaboss
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I LOVE crap!

Candlepower (abbreviated as CP) is a now-obsolete unit which was used to express levels of light intensity.

Candlepowerforums (abbreviated as CPF) a website, also obsolete, drive

Slim Pickens
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I for one support this Yeti-free zone seeing how my clan of Sasquatches has been at war with the Yeti for untold millenia. Drivelousdrivel…I’minthankyoutexaspyro

wikiman
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I don’t have a lux meter so… I like crap!

CheapThrills
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Same here, so I like crap!

Backpacker Light
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I like crap

but

I need a light meter for sure.

The lighter the brighter the better.

ricardo
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I like crap
Anzycpethian
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Meeeeeeeeeeeeeow!

"Do not Weep. I shall draw all Things which perish into myself When I am lifted from the Earth." ~ Begotten (1991)

Megalodon
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I like crap, thanks for this giveaway!
DB Custom
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I like the idea of having a light meter, and am considering purchasing one just on the reasoning that the odds are against me winning this one. But how would I know if it was off, 20% or otherwise? Is that where having a light with a semi-known output comes in handy? For example, the EDC+ Triple XP-G2 was measured in a lumisphere as having 720 lumens out the front. So that would be the benchmark in testing a new lux-meter? How then is lux converted to lumens? And as far as that goes, who knows I COULD win this one, the question still applies as to how to read the lux given in an interpretation of lumens. Is it as simple as dividing the number given as lux by the 720 previously tested on the EDC+ when testing the EDC+ to derive the multiplier?

How is such a device used? Pretty much point-blank? A foot from the sphere? A meter? 10 meters? All these points and an average taken? How do you infer the lumen output of a floody light versus a light with a quite intense hot spot? Obviously those are 2 different beasts, the one with the hot spot will show more lumens at a meter than the floody light will sheerly based on the amount of light that does not hit the meter.

Is it possible to build a lumisphere from a meter such as this one? How difficult is that? I’ve seen builds of lumispheres on here and elsewhere and there are some great idea’s out there. The one using a large kids ball and covering it with paper mache seems like a real winner. One of those 24” or even 30” balls would be killer, making the shelf for the lux meter’s globe to sit on wouldn’t be all that difficult and it’d be great to know exactly what difference a given driver made or an upgrade to a copper star with next level emitter. Heck, even a change in battery brand or chemistry would be noticeable if you could measure the output in a precise manner! So an aperture based opening with 8 or 9 blades would be good to allow lights of different sizes to easily be used, simply dial in the correct opening diameter to allow minimal or no light loss for the diameter of the head being used, this could be in association with a variable height shelf on a slider with a thumb screw so that any light would lay on the shelf and easily be adjusted to center in the aperture. I think this could be pretty darn cool!

And it all starts with the ability to measure the light. Thank you TexasPyro for starting this snowball rolling down the steep slippery slopes of flashaholism! Smile Enough drivel?

ToyKeeper
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DBCstm wrote:
How then is lux converted to lumens? And as far as that goes, who knows I COULD win this one, the question still applies as to how to read the lux given in an interpretation of lumens. Is it as simple as dividing the number given as lux by the 720 previously tested on the EDC+ when testing the EDC+ to derive the multiplier?

How is such a device used? Pretty much point-blank? A foot from the sphere? A meter? 10 meters? All these points and an average taken? How do you infer the lumen output of a floody light versus a light with a quite intense hot spot?


Lux is generally not convertible to lumens; that’s why we need integrating spheres. There is no simple formula to convert between the two, for exactly the reasons you asked about in the second paragraph.

To use it, ideally you’d take a reading exactly one meter from the light, and look for the absolute brightest spot in the beam. However, many throwers still have a donut in their beam at this distance, so you must instead measure from farther away and convert the value back to what it would be at 1 meter by using the inverse square law. Double the distance and the value changes by a factor of four. Triple the distance and it changes by a factor of nine. Etc.

mhanlen
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I love crap!

M78
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I like crap. Lol

DB Custom
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The inverse square law is a constant issue in Photography when flash units need to be used. Difficult to explain to point-n-shoot users with tiny underpowered flash units pulling power from the same power supply as the camera.

Thanks for the help, appreciate it.

mrmatt
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as witnessed by the condition of my basement. Now crap that measures things, that’s as good as gold!

XkennX
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I’m in!! im full of crap lol

Nightbird95
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ToyKeeper wrote:
DBCstm wrote:
How then is lux converted to lumens? And as far as that goes, who knows I COULD win this one, the question still applies as to how to read the lux given in an interpretation of lumens. Is it as simple as dividing the number given as lux by the 720 previously tested on the EDC+ when testing the EDC+ to derive the multiplier?

How is such a device used? Pretty much point-blank? A foot from the sphere? A meter? 10 meters? All these points and an average taken? How do you infer the lumen output of a floody light versus a light with a quite intense hot spot?


Lux is generally not convertible to lumens; that’s why we need integrating spheres. There is no simple formula to convert between the two, for exactly the reasons you asked about in the second paragraph.

To use it, ideally you’d take a reading exactly one meter from the light, and look for the absolute brightest spot in the beam. However, many throwers still have a donut in their beam at this distance, so you must instead measure from farther away and convert the value back to what it would be at 1 meter by using the inverse square law. Double the distance and the value changes by a factor of four. Triple the distance and it changes by a factor of nine. Etc.

Thanx for this info. I have no idea how to get the lumen reading either. Smile

ToyKeeper
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Nightbird95 wrote:
Thanx for this info. I have no idea how to get the lumen reading either. Smile

Are you familiar with how to integrate the area under a curve via calculus? Measuring lumens is kind of like that, except instead of measuring each point under the curve we try to flatten the curve out first then measure only one point.

The easiest way to estimate it is to do a ceiling bounce test. Shine a light at a white ceiling, put a lux meter somewhere else in the room, and read the value. Calibrate by using lights with known outputs and developing a function to convert ceiling bounce values into ANSI lumen values. It’s not very accurate, but at least it’s easy and requires very little special equipment.

The next best way is to build a large white sphere with two holes in it… one for a flashlight to point into, and one fitted tightly for a lux meter. This is similar to the ceiling bounce in that it assumes the light will be fairly evenly dispersed and only measures one point, but it’s better at dispersing the light evenly and retains more energy so there’s more to measure. This is probably as complex as almost anyone on BLF cares to attempt.

The proper way, the way we’re trying to emulate, is to measure the output at every point in the beam and add the values together. Much like measuring the height of a curve at every point and adding the values together as the width of each sample approaches zero, we’re trying to take the integral of the 3D beam pattern function. This is prohibitively expensive though, and requires lots of relatively complex hardware.

Realistically, you could probably do fairly well with a cheap lux meter, a styrofoam cooler, and a lot of calibration. Or papier mache around a beach ball. Or a milk carton. That’s how selfbuilt does it. It was based on this design.

33696933
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2222

Nightbird95
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ToyKeeper wrote:
Nightbird95 wrote:
Thanx for this info. I have no idea how to get the lumen reading either. Smile

Are you familiar with how to integrate the area under a curve via calculus? Measuring lumens is kind of like that, except instead of measuring each point under the curve we try to flatten the curve out first then measure only one point.

The easiest way to estimate it is to do a ceiling bounce test. Shine a light at a white ceiling, put a lux meter somewhere else in the room, and read the value. Calibrate by using lights with known outputs and developing a function to convert ceiling bounce values into ANSI lumen values. It’s not very accurate, but at least it’s easy and requires very little special equipment.

The next best way is to build a large white sphere with two holes in it… one for a flashlight to point into, and one fitted tightly for a lux meter. This is similar to the ceiling bounce in that it assumes the light will be fairly evenly dispersed and only measures one point, but it’s better at dispersing the light evenly and retains more energy so there’s more to measure. This is probably as complex as almost anyone on BLF cares to attempt.

The proper way, the way we’re trying to emulate, is to measure the output at every point in the beam and add the values together. Much like measuring the height of a curve at every point and adding the values together as the width of each sample approaches zero, we’re trying to take the integral of the 3D beam pattern function. This is prohibitively expensive though, and requires lots of relatively complex hardware.

Realistically, you could probably do fairly well with a cheap lux meter, a styrofoam cooler, and a lot of calibration. Or papier mache around a beach ball. Or a milk carton. That’s how selfbuilt does it. It was based on this design.

Whoa! Shocked

This information will keep me ‘busy’ during off hours for a few days once I get the lux meter I ordered as I’ll be building my own light meter. I think a sphere light box distributes light better than a cube light box. The only problem would be finding a sphere styrofoam cooler. :~

I love to improvise and I’m looking forward to completing my very own light box soon.

Thank you very much ToyKeeper! :bigsmile:

texaspyro
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Nightbird95 wrote:
The only problem would be finding a sphere styrofoam cooler.

http://www.smoothfoam.com/product/10073.html

The top of the inside domes has a flat spot. You can leave it as is or, even better, sand it to match the contour of the sphere.

Pinetreebbs
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Especially light crap.

Thank You.

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im in

One Mode High
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If I had a LUX Meter, I’d measure all my lights. I’d measure the sun on a cloudy day, I’d measure street lights and house lamps, and fluorescents and LED’s. I’d figure out a way to convert it to Lumens to compare to the manufacturer’s claims. I’d measure the output of different battery chemistries and find out just how much more intensity I’d get from 10440’s versus AAA’s, or even 14500’s vs AA’s.

Nightbird95
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texaspyro wrote:
Nightbird95 wrote:
The only problem would be finding a sphere styrofoam cooler.

http://www.smoothfoam.com/product/10073.html

The top of the inside domes has a flat spot. You can leave it as is or, even better, sand it to match the contour of the sphere.

Oh! Cash

Thanx texaspyro!

ledoman
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It can be usable crap, I think. I’m in, thanks!

gerald_clark
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I like crap.
Actually, most of my lights are crap too.

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