Incandescent IR power
nicks...@ece.villanova.edu
WVC200 webcam. The data sheet says it can work at 2 lux and it has an IR
filter (what does that do?) The vet says it's not a good idea to keep
the 10'x20' stall lit and the horse awake all night.
Amazon sells $50 low-power IR LED arrays, with mixed reviews.
Would a 100 W incandescent bulb run at low voltage work as well?
With some sort of IR filter (exposed film?) over the bulb?
So far, Linksys hasn't been helpful. When I asked on the phone about
spectral sensitivity, the Indian-accented person asked me what OS
I was using :-)
Nick
JB
<nicks...@ece.villanova.edu> wrote in message
news:fncj3b$e...@acadia.ece.villanova.edu...
Your webcam is not sensitive to IR due to the filter (usually built onto the
actual imaging sensor itself) so an IR illumination source would be no use.
Only monochrome CMOS or CCD cameras 'see' into the NIR where you could use
~800-900nm LEDs successfully for 'illuminaton'.
If you do actually need a colour camera, you typically need >2Lux of visible
illumination. If you can accept monochrome images, buy an appropriate mono
camera and use IR leds.
JB
mrob...@worldnet.att.net
In sci.engr.lighting nicks...@ece.villanova.edu wrote:
> I want to put a picture of a pregnant horse on a website using a
> Linksys WVC200 webcam.
I've played around just a little with webcams and IR LEDs and IMHO the
best way to figure out if a particular webcam will work is to try it and
see. If you guess right the first or second time it can be an
inexpensive way to get an IR camera; if not you end up paying a lot of
shipping charges or spending a lot of time at the store doing exchanges.
If you move up into cameras that are sold as security cameras,
especially black-and-white ones that are sold for low-light use, IMHO
your luck gets a lot better. On the other hand, these cameras are more
expensive, and they usually have just a composite video output, so you
will need a video capture card of some kind. If you can tolerate lower-
quality images, run the security camera to a standard TV monitor, and
point a webcam at the TV monitor. (If you are writing a grant, call
this a "single-conversion superheterodyne lightwave reciever" instead.
Sounds much more fundable than "pointing a webcam at a TV set". :) )
Another option might be a "board" camera. These don't have nice
packages but can be inexpensive.
http://gargravarr.cc.utexas.edu/owl/2006/box/ is an example (with specs
for the camera used) of using an IR camera and IR LEDs to observe
animals, albeit in a much smaller space than a horse stall. Again,
these will probably only have a composite video output, so you'll need
extra hardware to get the video signal into the computer.
> The vet says it's not a good idea to keep the 10'x20' stall lit and
> the horse awake all night.
Something to check is whether horses can see IR or not.
http://www.journalofvision.org/1/2/2/Carroll-2001-jov-1-2-2.pdf (linked
from http://www.journalofvision.org/1/2/2/ ) suggests they're not too
good at it, so using IR for light that's "invisible" to a horse may be
OK.
> Amazon sells $50 low-power IR LED arrays, with mixed reviews.
If you don't mind doing the work, you can probably make something just
as good with a fistful of IR LEDs and a power supply from Mouser or
Digi-Key. It might also be useful to spread the LEDs around the stall a
bit, instead of having them all in one place.
> Would a 100 W incandescent bulb run at low voltage work as well?
This is what was used in the paper linked to above. They had a fancy
tunable filter, though.
If you can accept a succession of still images, rather than video, using
a digital still camera might be another way to go. If you can find some
cameras old enough to be cheap, you might use more than one to get
different angles or shorter times between pictures. (This will be
easier to do with USB cameras but is probably possible with older
cameras that only had a serial port.) Googling finds
http://www.wrotniak.net/photo/infrared/ on using digital still cameras
in IR and there are probably many other sites.
Of course, all this stuff needs to get installed up high or behind glass
or otherwise protected from the horse. She might get annoyed and smash
the camera if she finds out she's not getting a cut of the click-throughs.
:)
Matt Roberds
phil-new...@ipal.net
| I want to put a picture of a pregnant horse on a website using a Linksys
| WVC200 webcam. The data sheet says it can work at 2 lux and it has an IR
| filter (what does that do?) The vet says it's not a good idea to keep
| the 10'x20' stall lit and the horse awake all night.
CCDs are inherintly sensitive to some of the IR band. That's actually a
bad thing for usual visual band usage. So a filter is added to _block_
IR from reaching the CCD layer. It's often integrated with the CCD. So
this won't accomplish what you want.
For many high end cameras, mostly digital SLRs, there are companies that
will modify the camera to pick up IR. They can replace the filter with
one that only partially blocks IR, or lets it all in. And they can even
block the visual band (black filter), if desired. But I don't know if
anyone does this with webcams.
| Amazon sells $50 low-power IR LED arrays, with mixed reviews.
| Would a 100 W incandescent bulb run at low voltage work as well?
Not really. You have to be rather low in voltage to avoid too much
visual, and the power is way reduced that way.
| With some sort of IR filter (exposed film?) over the bulb?
A "black" IR-pass-only filter would be used. They are, however, expensive.
| So far, Linksys hasn't been helpful. When I asked on the phone about
| spectral sensitivity, the Indian-accented person asked me what OS
| I was using :-)
Almost certainly it will be sensitive only in the visual band.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-200...@ipal.net |
|------------------------------------/-------------------------------------|
Jeff
That's the way to go. Frys.com has an assortment of surveilance
cameras with built in IR arrays.
As far as the dim bulb goes, you'll find that cameras and lenses
sensitive to long wave IR are expensive. The IR LEDs are shorter wavelength.
On a related note. Camera conversion to IR sensitive are getting
popular. They remove the IR filter and do some mumbo jumbo with the
internals. They don't tend to be very sensitive, but give all the cool
IR effects such as dark skies and bright foliage.
Jeff
> JB
>
>
Thomas Paterson
An easier approach would be to uplight the ceiling with a saturated
blue at VERY low intensity. Even basic skyglow gives illumination to
the 2 lux range. Horses may or may not be disturbed. I asked my
partner, who is a vet, she says they generally see well in reds and
something like green, as well as total intensity. She's referred me
to a specialist horse opthamologist friend of ours, who can tell us.
Before I do, I'd like to know for what purpose you're doing this - I
trust it's not some kinky www.funwithhorses.com type of idea. I think
we'd all be hesitant to help on that one.
Thomas.
nicks...@ece.villanova.edu
>An easier approach would be to uplight the ceiling with a saturated
>blue at VERY low intensity.
Hmm. A string of little blue Christmas bulbs?
>... I'd like to know for what purpose you're doing this
The mare's owner lives about 5 miles away and would like to know when
the baby's coming so she can be here and help if needed. So far, she's
been sleeping on a cot in the barn. It might also be nice to watch
the mommy and baby together later.
No luck so far getting any IR sensitivity info from Linksys, nor
any answer as to whether the filter can be removed.
Nick
nicks...@ece.villanova.edu
>any answer as to whether the filter can be removed.
Then again, maybe it shouldn't be removed. According to this description:
.... The comprehensive video features include an IR filter cut which
allow you to see the images in low or no light environments when an IR
lamp is used.
Nick
Thomas Paterson
I'd suggest that your blue christmas lights might be a very practical
idea. Put them on a shelf lighting upwards and see if that is enough
for visible light. Paint the shelf white to make sure you squeeze
some light out of it. If not, you can always go with blue LED
ropelight - start with a long piece and cut down until you're
approaching the limits of the camera.
Remember - the lights need to be indirect, the horse can't see them.
Thomas Paterson
> WVC200 webcam. The data sheet says it can work at 2 lux and it has an IR
> filter (what does that do?) The vet says it's not a good idea to keep
> the 10'x20' stall lit and the horse awake all night.
It's probably too late to be useful, but I had dinner the other day
with a horse ophthalmologist (they do exist). The answer is that
horses don't really see red, so indirect red light at very low level
should be fine - just enough for the camera to work. Probably best to
replace the LED ropelight/christmas lights noted in my post of January
31 with red versions if still relevant.
Horses (I'm told) generally give birth between 2 and 4am, certainly
always at night. It's an evolutionary thing - horses are prey animals
and don't want to be seen when they are vulnerable. That means that
it's important that they're unaware of the observation.
I hope everything went well, we'd love to see photos.
Thomas.
redbelly
Here is how to remove the IR-blocking filter in one type of camera.
If you're mechanically inclined, you may be able to adapt this method
to your own camera model.
http://www.abe.msstate.edu/~jwooten/camera/lense.html
Note that, in addition to removing the filter, a piece of clear glass
is substituted for it. Otherwise the camera could no longer focus the
image onto the sensor array.
Regards,
Mark
Terryc
> On Jan 25, 6:01 am, nicksans...@ece.villanova.edu wrote:
>
>>I want to put a picture of a pregnant horse on a website using a Linksys
>>WVC200 webcam. The data sheet says it can work at 2 lux and it has an IR
>>filter (what does that do?) The vet says it's not a good idea to keep
>>the 10'x20' stall lit and the horse awake all night.
Light with infrared glass covering so the scence is only lit with IR.
most of the cams I've played with are sensitive into the IR range and so
will give you a good image.