On 20/01/2017 19:48, Scott wrote:
On Fri, 20 Jan 2017 19:45:17 +0000, dennis@home
wrote:

On 20/01/2017 19:38, Scott wrote:
On Fri, 20 Jan 2017 15:26:48 +0000, dennis@home
wrote:

On 20/01/2017 14:44, Brian Gaff wrote:
I don't like halogen. gives me a headache even though I cannot see. I get
this spreading green yellow flashing haze when I go near Halogen lighting.
Goes to prove I guess that even blind eyes can give strange effects.
Brian


The only difference between halogen and tungsten lights is the
temperature they run at.

Surely the temperature directly influences the frequency of the light
output?


It moves the peak of the curve slightly to the blue.
It doesn't make them emit any visible light that wasn't already visible.

'Visible' is a not entirely relevant concept for someone who is blind.
If Brian is experiencing headaches with these particular lights could
it not be related to the colour temperature.


I can't see why it should be.

The outlier is the conventional filament bulb. Halogen light is slightly
*more* like natural sunlight. You could get blue coated filament bulbs
to fakte 6000K daylight for photography in the old days.

Before modern auto white balance digital cameras film was very tetchy
about colour temperature with fluorescents being a green cast disaster.

--
Regards,
Martin Brown