Lights. Is bigger better?

[joel0407]

I don't want this thread to get carried away with brands, styles (flood or spot) or types (Hallogen - HID). Some of you know I have some pretty strong view on that stuff and other on here also have their own views on that stuff.

This is just a question of the refector design. I have raised this question with myself from some reading about projector lights.

Before I get too much into projectors lights. If a reflector is bigger, will the light output be any greater?

I mean the light source puts out X amount of light. No matter whether you have a 300mm round reflector or a 100mm round reflector, you cant make anymore more light. All you can do is relfect the light that is generated by the source. I suspect providing the reflector is of good reflective quality then the light output will be the same.

If what I suspect is right, then why do we have big lights? I am suspecting the answer to this one will be simply a cost of production. I mean it must be easier to produce the right curve of the relfector with a bigger light as the tolerance would be far greater.

Now on to projectors. There is a HID forum with these guys seem more interested in style than light output. Performance to them is more about sharpness of the cut off line when on low beam and the colours at the cut off line. No one seems concerned about how bright they are.

Projectors lights have a very small refector that just reflects the light straight forward then the lens determins the beam patern and a shutter creates the cut off for low beam.

I'm wondering why no one produces projector driving lights. Many of the guys on the HID forum get their projectors second hand from the wreckers. Unfortunatly for me in Darwin there are not too many wreckers and then even less vehicles that would have projectors in them so they are expensive for me.

It makes sense to me to reduce wind drag that we get with big driving lights and the air flow we restrict to our radiators with big lights, why not have small ones.

One advantage I can see from big lights that if you get a bug on a large light you may one block 1% of the light output but get a bug on a light with a frontal area no bigger than a tennis ball and you could cut 10% of light output.

I'm keen for others thoughts.

Happy Days.

[Aaron IIA]

The bigger the diameter of the reflector, the greater the amount of light captured and reflected. I can't remember if it is a direct ratio, squared ratio, or factor of pi ratio. Think about the large reflectors that old ethyne burning headlights had. They really needed to maximise their small output. Also think of the fortress searchlights. They have a five foot diameter mirror for a reason.

Aaron

[Xtreme]

Disregarding light output. bigger is not better in regard to possible stone chip damage. So as with everything, you may need to reach a compromise between too big and too small. :D

[joel0407]

The bigger the diameter of the reflector, the greater the amount of light captured and reflected. I can't remember if it is a direct ratio, squared ratio, or factor of pi ratio. Think about the large reflectors that old ethyne burning headlights had. They really needed to maximise their small output. Also think of the fortress searchlights. They have a five foot diameter mirror for a reason.

Aaron

But did they have big relfectors becasue they had poor reflective reflector or did they just think bigger was better in the old days.

My theory is the the further you get from the bulb the less intense the light is. The light reflected in 1 square CM of relfector very close to the bulb would be far more intense than 10cm2 of reflector furhter away from the bulb (Light source).

At this stage i'm not interested in heat or anything else, just how much light will go forward. We all know smaller will get less stone chips and block less air and be lighter and all the other benifits of being small but the question is in theory should they put out the same light?

Happy Days

[joel0407]

The bigger the diameter of the reflector, the greater the amount of light captured and reflected.

Aaron

Further more this might be correct if we were relfecting light from the sun or something but or light source is only small.

Big or small we only capture the light at the rear of the light source. the back 180 degrees.

Happy Days

[superquag]

Its easier from a production and quality control viewpoint, to have a larger, (within reason!) 99% accurate reflector, than a tiny, 110% perfect one.

Best way to see this, and the benefit of 'larger diameter/depth' is to draw a deep parabola. The focus will be quite close to the inside of the apex.
ANY ray of light that comes from the focus, will bounce off the inside surface and end up parallel to the axis line, so all rays of light will be going in the same direction.

So, the deeper/wider is the reflector, the more rays are captured or controlled...and head off in the same direction. - Frontwards

Go the ridiculous, and cut the reflector right down to the same height as the globe.... see how many rays of light are.... escaping.

IF you make the reflector stupidly deep, then nearly every 'bit' of light that leaves the luminous source will end up going where it's needed... straight ahead. Depends on what you want or need or can pay for.

There's your answer.

Only interesting bits are... balancing cost of large reflector and LENS, the body, mounting, wind-blocking of radiator, weight. market expectations, hoon-factor....

6" or 150mm seems to be the lower end of sensible-sized 'small' spotties. whereas 8"+ is the preserve of someone with deep pockets and space to mount them.
3" - 4" are usually built down to an available hole...

I dislike projectors, due to lack of precise control, waste of potential light, glare, cost, and other .... 'reasons'...:eek: . just don't like 'em. Don't think they're particularly efficient or good, for the cost that's sunk into them.

[bee utey]

A big reflector is generally deeper than a small one so catches more of the light if the focus point is well back from the front edge. You don't want a small diameter reflector too close to a halogen filament unless its in a vacuum, otherwise it will discolour from the heat. The old Cibie Super Oscar is an excellent light because of this depth, along with the quality of the reflective surface. Hella used to make a long range high beam insert for dual headlamp systems that was a great light as it was about 1" deeper than their regular high beam inserts. Some of the LED lamp manufacturers have realised this as well and now make their light bars with deep reflectors to get more distance out of them.

[Vern]

Its all about the parabolics:)

[Blknight.aus]

you can only get out as much light as you put in.

the size and shape of your reflector dictates the cost accuracy and life of the reflector (a lot less relevant for LED based stuff)

older reflectors were larger to deal with heat and ease of manufacture especially when you start talking lighthouse size lenses in the day to get the required amount of light you made a lot of heat which if you put it too close to the light source would deform and loose beam coherency.


Generally a larger reflector will allow you to place the light source deeper inside the reflector giving you the ability to more tightly focus the projected light "beam" and reduce light "splash" which is exactly what you want for a spot light, less so for a flood light. A more focused light also appears to be brighter. than the same amount of light with "splash" around it, easy enough to demonstrate, shine a torch on the wall with the lights on and then turn the lights off. Now do the same thing and put a spot light meter in the point of the beam and repeat, same numbers different visual result.

[JDNSW]

In theory, the size of the reflector does not change the brightness of the beam from it, provided that the reflector covers the same solid angle for each size.

However, if we look at some of the assumptions in this theory, the result is not so clear.

Firstly, the theory assumes a point source - a filament is not a point source, and the smaller the reflector, the further this is from reality - the beam will be more accurate from the larger reflector.

Secondly, the smaller the reflector, the more important become the inevitable imperfections, both in the reflector and the lens, and the insects etc on the lens, as each imperfection affects a larger proportion of the reflector.

Thirdly, the smaller the reflector, the larger the proportion of it is effectively masked by the bulb mounting.

Fourthly, as mentioned above, a small reflector is likely to place the hot bulb close to the reflector and lens, causing deterioration of them both.

So overall, the larger the reflector, the more light in the beam, although as with many situations you have diminishing returns. (Projector systems usually waste a lot of the light generated, but this is compensated for, at least for low beam, by being able to provide a very accurate beam.)

John

[Eevo]

is light a wave or a particle?

[87County]

is light a wave or a particle?

Tricky question......😊

[Blknight.aus]

both depending on which light you look at it in.

[JDNSW]

is light a wave or a particle?
Yes.

John

[carjunkieanon]

is light a wave or a particle?

Let me get a box and a cat :)

[Eevo]

Let me get a box and a cat :)

lol
wrong experiment.

[carjunkieanon]

lol
wrong experiment.

Hah :) Not the way I set it up :)

[joel0407]

A big reflector is generally deeper than a small one .

I can't say I could agree with this.

A flater dinner plate shape relfector will give a spot beam where a deep breaky bowl shape reflector will give a wider flood beam. Irrelevant of the size.

[joel0407]

Its all about the parabolics:)

As per my above post. I suspect parabolics determines the focus of the light, not how much light is reflected.

Happy Days.

[Blknight.aus]

I can't say I could agree with this.

A flater dinner plate shape relfector will give a spot beam where a deep breaky bowl shape reflector will give a wider flood beam. Irrelevant of the size.


As per my above post. I suspect parabolics determines the focus of the light, not how much light is reflected.

Happy Days.

ummm....

the parabola of the reflector with the light source at the focal point gives you a spot. the flatter the reflector the further away the focal point of the lens is from the center of the lens. (I am not getting into offsets) a flatter reflector will only return a spot if the light being projected onto the reflector is already "focused" it ties into the reflection angle and if you're using a reflective backed reflector (like a mirror) deflection (which doesnt apply if your using a reflector with the mirror surface on the front (like a chrome plated plastic headlight reflector)

very roughly.

IF you consider the light source to be a perfect ball of light inside the reflector the wider the angle that you can directly see the light source from without it being blocked by the "rim" of the reflector the more light you loose the ability to focus.



on a side note, Schroedingers experiment is always a valid one. any time you conduct it theres a 50% chance that there will be one less cat around.

[Greatsouthernland]

Depends on where you stand, the focal point can be adjusted and is where the light is 'brightest', so it's subjective...depends on 'where' you want the light to be brightest.

Stimulation and frequency matter too, 'bright' according to who or what and on what background. L A S E R - Light amplification (by the) Stimulated Emission of Radiation... brightness (energy) is also a function of the chosen frequency. I.e. Green = smaller wavelength than Red, therefore through the same medium/atmosphere has more energy/penetration/distance = 'brightness'? ... extrapolate this to Blue & Violet and while 'brighter' / more powerful, in its spectrum, mostly wasted on human eye receptors, but if you were an insect, or utilising electronic means to 'decipher' what you've illuminated at great distance but your human eye can't register (think remote sensing i.e. Landsat) now it's VERY useful light.

So as a wave of particles :angel:, there's a 'perception' as unique as your own eyes or the distance you 'expect' the focus to be on...or how you could electronically use what you've illuminated but can't see...

Hard to truly know what your end goal is and where another point of view can reinforce it, so a real can of glow worms you've opened up there...I've seen some small LASERs that are brighter than the biggest light house...not the size that counts, but how you use it - didn't see that coming did ya?

[joel0407]

ummm....

the parabola of the reflector with the light source at the focal point gives you a spot. the flatter the reflector the further away the focal point of the lens is from the center of the lens. (I am not getting into offsets) a flatter reflector will only return a spot if the light being projected onto the reflector is already "focused" it ties into the reflection angle and if you're using a reflective backed reflector (like a mirror) deflection (which doesnt apply if your using a reflector with the mirror surface on the front (like a chrome plated plastic headlight reflector)

very roughly.

IF you consider the light source to be a perfect ball of light inside the reflector the wider the angle that you can directly see the light source from without it being blocked by the "rim" of the reflector the more light you loose the ability to focus.



Ok so am I right in saying this is all related to focusing the avalible light with relfector shape.

This doesn't mean a bigger diameter refector will reflect more light.

?????

Happy Days

[joel0407]

Depends on where you stand, the focal point can be adjusted and is where the light is 'brightest', so it's subjective...depends on 'where' you want the light to be brightest.

Stimulation and frequency matter too, 'bright' according to who or what and on what background. L A S E R - Light amplification (by the) Stimulated Emission of Radiation... brightness (energy) is also a function of the chosen frequency. I.e. Green = smaller wavelength than Red, therefore through the same medium/atmosphere has more energy/penetration/distance = 'brightness'? ... extrapolate this to Blue & Violet and while 'brighter' / more powerful, in its spectrum, mostly wasted on human eye receptors, but if you were an insect, or utilising electronic means to 'decipher' what you've illuminated at great distance but your human eye can't register (think remote sensing i.e. Landsat) now it's VERY useful light.

So as a wave of particles :angel:, there's a 'perception' as unique as your own eyes or the distance you 'expect' the focus to be on...or how you could electronically use what you've illuminated but can't see...

Hard to truly know what your end goal is and where another point of view can reinforce it, so a real can of glow worms you've opened up there...I've seen some small LASERs that are brighter than the biggest light house...not the size that counts, but how you use it - didn't see that coming did ya?

I think that is sort of my point. Disregarding the light source, whether it is a lazer, HID, Halogen or what ever, a bigger reflector wont make the light going out the front any greater.

Bigger lights might use more material but they are just easier to manufacture due to the ability to have higher tolerances in the reflector shape and quality of reflection.

????????

[Blknight.aus]

Ok so am I right in saying this is all related to focusing the avalible light with relfector shape.

correct

This doesn't mean a bigger diameter refector will reflect more light.

sound in theory, but I wouldnt go calling that and absolute fact its an apples VS oranges thing

?????

Happy Days




I think that is sort of my point. Disregarding the light source, whether it is a lazer, HID, Halogen or what ever, a bigger reflector wont make the light going out the front any greater.

True, however as the reflector is easier to build better use can be made of the available light

Bigger lights might use more material but they are just easier to manufacture due to the ability to have higher tolerances in the reflector shape and quality of reflection.

Generally true

????????


Fun isnt it..

[kenleyfred]

I got to know the Lighthouse keeper on Great Inagua, (southern most of the Bahama Islands), he showed me around his Lighthouse which is(was) one of the few remaining manned lighthouses. It was very interesting, the rotation of the light was created by the constant pull supplied by weights that hang down the guts of lighthouse and have to be pulled back up every couple of hours. The light source, which from memory, was visible for 20nm was supplied by a single kerosine burner, similar to what you can buy in any camping store. He also had to top up the kerosine every day.
What made that little "candle" visible for 20nm was the biggest thickest lens I have ever seen.
So big lenses can overcome poor light sources.
Kenley

[Greatsouthernland]

I got to know the Lighthouse keeper on Great Inagua, (southern most of the Bahama Islands), he showed me around his Lighthouse which is(was) one of the few remaining manned lighthouses. It was very interesting, the rotation of the light was created by the constant pull supplied by weights that hang down the guts of lighthouse and have to be pulled back up every couple of hours. The light source, which from memory, was visible for 20nm was supplied by a single kerosine burner, similar to what you can buy in any camping store. He also had to top up the kerosine every day.
What made that little "candle" visible for 20nm was the biggest thickest lens I have ever seen.
So big lenses can overcome poor light sources.
Kenley

Focus plus tuning depending on your 'visual' receptor (wavelength/filters). Remember when focusing to a distance, intensity is less concentrated in front of and behind that point. That's why I said it's a perspective thing, probably why it's popular to have narrow and wide beams installed together instead of only a 'pencil' beam reducing peripheral 'scatter', like they do with many LED bars.

[JDNSW]

I got to know the Lighthouse keeper on Great Inagua, (southern most of the Bahama Islands), he showed me around his Lighthouse which is(was) one of the few remaining manned lighthouses. It was very interesting, the rotation of the light was created by the constant pull supplied by weights that hang down the guts of lighthouse and have to be pulled back up every couple of hours. The light source, which from memory, was visible for 20nm was supplied by a single kerosine burner, similar to what you can buy in any camping store. He also had to top up the kerosine every day.
What made that little "candle" visible for 20nm was the biggest thickest lens I have ever seen.
So big lenses can overcome poor light sources.
Kenley

What you have with a lighthouse is a very narrow, accurately focused beam - basically the same as a projector type headlamp.

Unfortunately, what is needed from a headlight is a wide beam, not a narrow one.

John

[Greatsouthernland]

What you have with a lighthouse is a very narrow, accurately focused beam - basically the same as a projector type headlamp.

Unfortunately, what is needed from a headlight is a wide beam, not a narrow one.

John

For close range, yes. But for further ahead, depending on speed and terrain, one or four:angel: narrow beams are nice. I had some aircraft landing lights on the Datto last century :cool:

Something like these should do the trick for extra distance...

https://en.wikipedia.org/wiki/Light_beam#/media/File:Wtc-2004-memorial.jpg

[Pedro_The_Swift]

from another angle,,

these guys have unlimited funds, so whatever they think works best is what they use,,

check out the lights.

and they test their light setups as well as they test the rest of the car.

This years winner took 15 hours to finish at an average speed of 51mph.

https://plus.google.com/+ScoreBaja1000Race/posts/ggB94Koj2zh

its not a great corner but the cars are slow and in focus;)

[R2D2]

If you would like to speak to an engineer on lights, call Fyrlyt in Adelaide and ask for Paul. He will give you all the facts.

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