Re: Without intending offense

On Mon, 20 Feb 2006 19:21:27 +0200 Ioannis <morpheus@xxxxxxxxxxxx> wrote:
| <phil-news-nospam@xxxxxxxx> wrote in message
| news:dtcguq0d2v@xxxxxxxxxxxxxxxxxxxx
| [snip]
|
|> I am definitely very nearsighted. I forget the exact amount or the
|> presciption of my glasses. However, without my glasses, I do not see
|> much separation of red and blue.
|
| That's to be expected. Without the glasses point and extended sources become
| always extended, so the spectrum colors blur together, except at the edges.
| To see the difference at the edges, you have to have a source whose lines of
| emission have at least some minimum separation. Magenta LEDs are a good
| source to test this. They were discussed in another thread here sometime
| ago. Also HPM blacklights.

I also see exaggeration of this through automobile windshield tinting.


|> With the glasses (one single glass
|> element so no chromatic correction at all) the separation of red and
|> blue is quite significant.
|
| This separation again requires some minimum difference between spectral
| lines. Empirically I have found that it is quite visible with the Na/Th
| lines on MH's and with the Eu+/Tb+ lines on regular triphosphors. This is
| most pronounced when the rest of the spectrum is relatively empty. For
| sources whose spectrum contains additional stuff between the separation
| candidates, the effect is less pronounced. It doesn't happen with typical
| American type Na/Sc MH's for example, like the MetalArc, because their
| spectrum is relatively rich.

Maybe I should check out one of these to see what it looks like to my eyes.
But where to find one. Virtually all the MH type lights I see in places
like parking lots are of the "bad" variety for me.

There is a car dealer lot downtown that has a mix of MH and HPS lights in
separate fixtures. It makes for some interesting orange/blue shadows
where the lamps illuminate from different angles. Their MH's are all
"bad" but the HPS's are OK to my eyes.

I'd like to find out more about specific products and their spectral lines.
I've seen many sites selling bulbs online, but they give no technical
details, assuming you already know what you want (or more likely, know what
your fixture can accept).

I'm considering some kind of HID lighting for outdoor security illumination.
I'd like to explore the options. Although such lighting would not normally
be used for any kind of task lighting, and therefore shouldn't really be a
problem regardless of what I choose, at least knowing the options could let
me choose something that makes more sense for me.


| You can avoid triphosphors, but regular halophosphate fluoros are going to
| be gentler on this. Try the older warmer halophosphate fluorescents with a
| temperature of 3,000-3,500 K. These contain lots of continuous emissions and
| the blue mercury line (which stands at a great distance from the green and
| yellow lines) is highly suppressed. I don't notice any intense spectra
| around them, although again, if I look at the lamp through the edges of my
| glasses I do see the spectrum.

How do I identify these in a store (such as a home improvement box store or
an electrical/lighting supply store)?


| In retrospect it has nothing to do with arbitrary differences between
| spectral lines. It has to do with your glasses' pseudo-resolving power when
| they act as a spectroscope. So it basically depends on your prescription. A
| person with -20 diopters in each eye and glasses is bound to see spectra all
| around him no matter what, simply because the pseudo-resolving power of the
| lens edges acting as prisms is going to be so much greater than my
| average -4.50 diopter prescription.

I vaguely recall I have about -4.5 on one lens and -5.25 on the other.
I've lost the original prescription ***. Probably time to go back,
anyway.

My biggest concern for all this, though, is the possible spread of the
kind of rules now being imposed in Kalifornia that require a certain amount
of "high efficiency" (read: not incandescent) lighting in homes, especially
in a kitchen (where one would normaly have a significant amount of
lighting). For in my home, I can't accept anything but incandescent that I
have seen so far (aside from monochromatic stuff like the red step lights I
plan to put in which will probably be LED). Fortunately I don't live in
Kalifornia (and plan to never do so).

--
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| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
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