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Roger N. Clark (change username to rnclark)
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Scott W wrote:

> Mike Fields wrote:
> > Be careful pointing anything that is an IR source at an aircraft -

>>especially things like police helicopters where their IR cameras
>>will see yours. They may perceive you as a threat of some sort
>>since your IR source will be obvious on their cameras. Personally,
>>I would rather not have them considering me a possible threat !!

> The IR camera on police helicopters are mostly thermal, the IR an LED
> puts out is much shorter in wavelength.
> Scott

That's a good point. Thermal infrared cameras will work
predominantly in the 8 to 12 micron range. Visible light
is about .4 to .7 micron. IR LEDs put out light near
1 micron. Incandescent bulbs peak output between 1 and 2
microns. (By the way, for those interested, the reason
why fluorescent lights are so efficient is that most
of their energy goes into the visible band, whereas with
incandescent bulbs put out most of their energy in the
near-infrared.) (We need some infrared here: another snow
storm is starting to bury Denver again.)

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Kevin McMurtrie
Posts: n/a
In article <pan.2006. .org>,
JamesDorset <(E-Mail Removed)> wrote:

> Sony has a "nightshot" feature on some of their cameras and video-cameras.
> They advertise zero lux capability.
> Besides turning on one or more infrared LEDs, do these cameras put an
> infrared filter in front of the lens? Since the range of the IR LEDs is
> very limited, would "nightshot" give you an edge on recording aircraft and
> visible satellites at night?
> For shooting aircraft and visible satellites at night, could a Canon
> videocam simulate nightshot mode by putting an infrared lens in front of
> the lens? What would be the best video camera/lens combo for this type of
> filming?
> I really appreciate any info.....

The IR LEDs are just a hair beyond the red color; near IR. Some IR LEDs
are can be seen in total darkness as a colorless light. Some IR LEDs
and lasers look red but that's often actual red light from accidental or
intentional impurities.

Whether or not the camera's IR sensitivity is deep enough for astronomy
is something you'd have to test. I doubt it. IR sensitivity is usually
undesirable because it alters the image in ways that a natural eye does
not see. The Oly C2000Z tended to produce cyan halos with dimmed
incandescent lighting. It ruined many of my photos.
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