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Photons and true light of the stars... basic question

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#51 Freezout

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Posted 25 February 2024 - 02:04 PM

Thanks guys, extremely interesting to read! I wasn’t expecting that much. I am happy I started this thread.
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#52 moefuzz

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Posted 26 February 2024 - 08:44 PM

Thanks guys, extremely interesting to read! I wasn’t expecting that much. I am happy I started this thread.

I agree, there's more to the photon than meets the eye.

 

 

 

 As for coated lenses in eyepieces, I'm never quite sure what they do, never read up on it, although I very much doubt that they are passive image intensifiers as no wiring exists from them to your optical nerves.

 

 

Coatings block light.  Multiple coating can be used to tune light by utilizing certain/several colours while leaving a certain range untouched.

 

The popular and fair expensive OIII nebula filters utilize multiple coatings in which certain coatings block light up to the allowed bandwidth while other coatings block light above the allowed bandwidth.

 

This is why nebulae filters appear to darken the sky but still allow the nebulosity.

In essence and thru tricking the mindseye,  most perceive the nebulae as being somewhat brighter but in actuality, all you've done is make the nebulae stand out via filtering the 'excess' light that surrounds it (including light as close as your atmosphere or street lights) so in tricking the mindseye to think that the nebulae is brighter and/or more defined.

 

An analogy;

Many cities around the world have switched to "white" LED street lights.

Over time the heat of the LED may burn the coating off the LED destroying the filter that makes it appear white.

Once the coating is burned off the actual LEDs surface, what is left for us to see is the original spectrum of the actual LED before it was filtered.

 

Heat effected 'white' LED streetlights will then show their true colour which is quite a nice blue.

-All the odd blue street lights you see have more or less cooked the coating thus allowing all the previously filtered light to pass.

 

In actuality, the white spectrum of the light is still there and may be just as intense but now the rest of the spectrum is allowed to pass thus fooling the mindseye into thinking that it may or may not be dimmer in retrospect to the white street lights down the street.

 

So for the most part those odd pretty blue street lights may seem dimmer but in essence they are actually emitting more light as the filter has been removed.

 

This is a manufacturing defect and the heads for LED streetlights are not cheap.

Certain cities allow these blue street lights to stay in place as in reality they are still emitting the original white light (plus a few more photons).

 

Personally I wouldn't mind if our entire town turned blue.

The only problem with that is there *may* be a marked increase in crime in and around a blue street light as the criminals perceive it to be darker and thus safer to commit offences. But the research is still out on this effect.

 

cheers,

moe of the north


Edited by moefuzz, 27 February 2024 - 12:14 AM.

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#53 PKDfan

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Posted 26 February 2024 - 09:50 PM

Nope, there is no absolute time and space so the photons are not around million years old photons, they are actually quite young (ignoring the time before they reached the photosphere of their source star/object and only counting the post-photosphere time). We may be seeing the Andromeda Galaxy as it was millions of years ago but the photons aren't that old.


Nope !!

CS

#54 KBHornblower

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Posted 26 February 2024 - 11:13 PM

My remarks inserted in boldface. 

I agree, there's more to the photon than meets the eye.

 

 

 

 

 

Coatings block light.  Multiple coating can be used to tune light by utilizing certain/several colours while leaving a certain range untouched.

 

Coatings on lens surfaces increase the throughput by preventing reflection from the surface.  That is a far cry from blocking the light. I saw the explanation in a college physics course about the electromagnetic wave nature of light.  I must admit that I did not understand it completely.  Perhaps someone else could help.

 

The popular and fair expensive OIII nebula filters utilize multiple coatings in which certain coatings block light up to the allowed bandwidth while other coatings block light above the allowed bandwidth.

 

This is why nebulae filters appear to darken the sky but still allow the nebulosity.

In essence and thru tricking the mindseye,  most perceive the nebulae as being somewhat brighter but in actuality, all you've done is make the nebulae stand out via filtering the 'excess' light that surrounds it (including light as close as your atmosphere or street lights) so in tricking the mindseye to think that the nebulae is brighter and/or more defined.

 

...snip...


Edited by KBHornblower, 26 February 2024 - 11:14 PM.


#55 moefuzz

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Posted 26 February 2024 - 11:36 PM

Coatings on lens surfaces increase the throughput by preventing reflection from the surface.  That is a far cry from blocking the light. I saw the explanation in a college physics course about the electromagnetic wave nature of light.  I must admit that I did not understand it completely.  Perhaps someone else could help.

 

 

 

I think they were referring to anti glare coatings on lenses and not coatings for OIII nebula filters and or coatings on LED streetlights. Two different concepts but the same principles still apply.

 

The concept is still that coatings block specific wavelengths of light and in the case of Coated Lenses, you want to block reflections at both the perimeter and the multiple faces of the glass itself

as opposed to filters which are engineered to allow very specific bandwidths to pass thru all facets with the exception of the perimeter which may also be coated to block all reflected light..

 

Generally, the outside perimeter anti glare coating is black (paint) which effectively blocks all reflected light from sneaking in from the side facet of the lens or the filter as opposed to the face coatings which are bandwidth specif thus passing some frequencies while blocking others..

 

And there's a reason that things like the OIII nebula filters are hugely expensive as it takes serious engineering and a mix(ture) of different coatings to come up with the ->exact< formula to allow the very narrow intermediate bandwidth to pass thru almost unaffected,

 

You can learn more about it at websites like Edmund scientific who are masters of glass with much of what they do headed to space and or the military/industrial

 

https://www.edmundop...l-filters/610/#

 

cheers,

moe of the north

 

fig-4-cbf.gif


Edited by moefuzz, 27 February 2024 - 12:08 AM.

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