You also have to take into consideration whether the camera you are using is suitable for the complete invisable 950nm ir. I would buy that 850nm light I posted fro ebay and see how it reacts to the camera you're going to use and then filter it to see also how it reacts.
You mark them with invisible ink.
cunning ...
But how do you know the jar still contains invisible in?
Get out of that one Einstein. ;-)
Easy - you'd be able to find it in your workshop if it didn't.
Talk to a big mil-surplus supplier, like Anchor in Ripley. IR lamps are very old tech now (they were disposed of about 15 years ago), but they might still have something. They certainly had flat glass filters (laminated glass around an IR gel) in brand new cardboard boxes only a couple of years back.
They used to have the old IR searchlights from Chieftains. Now _that_ would have cooked your flytipper where they stood.
At below half voltage the halogen cycle wont run, so you've got a filament lamp like any other filament lamp. No halo cycle means no cleanup of deposits on the glass. OTOH at below even red hot there wont be significant depositing to begin with.
One can drop V until its not visible.
yes
Some LEDs vs a headlamp is a heck of difference in power. I would have thought a 2 or 3 watt lamp would be a closer match.
NT
I think the lower temp more then compensates for lack of recycling - I have a couple of under-run MR16s as bench lights which have lasted many years.
At which point you won't have much light - an IR filter will have a MUCH sharper cutoff than the slope of the sides of the lamps spectrum, so a lamp+filter will give you the best IR to Visible ratio.
There is no point in filtering LEDs as their output is fairly narrowband.
Just recieved an IR 48 led 850nm light,the glow off these is only just barely visable and can only be seen closeup to the light. Will post a pic of the results of its working capability during the dark later on.
Well that was a waste of £13...damn thing only works up about a 12",the beam is directional.
Fuck! it says 15m working distance,nah bloody chance and the leds are 3mm type,might of been better if they were 5mm. The only use it'll have is for a bird box.
Thanks for posting anyway George. I too have continued experimenting. The problem, as was explained in a link someone sent earlier up the thread, it's actually quite difficult to flood an area with IR light and not be seen. Using the filter material Guy sent is interesting, it works very well (with about 4 thicknesses) at quenching visible light from the sidelight of a car and still having the sidelight apparently as visible as its unfiltered opposite number, when viewed through the camera, but it does not noticeably light the surrounding area. Similarly a 12V spotlight has too restricted a field, as you would expect, it only illuminates the spot it is pointed at.
Next stage is to add a light dimmer to an outside floodlight circuit at home and that will have to wait until I next get the ladder out.
AJH
Apparently the guy said it all depends on how sensative the camera is? the resolution on these cams I have is only 380lines and the lux is not entirely good. So I'm gonna see if I can find my B/W camera and give that a shot.
Ureka!! seems the camera plays an important role on the amount of area and distance the IR light emits. Will post a pic tomorrow when I can hook up this camera. ;-)
In message , George wrote
You may find that there is a IR blocking filter fitted between the camera lens and the camera detector.
Was there enough?
I thought about this,but it doesn't have a filter behind the lense...probaby just the camera being poor quality although its fine in daylight. Anyway I now know the IR light is working ok and was worth £13. ;-)
Yes I think so thanks, I'm still experimenting in the garden. As I intend to deploy the camera in a parked car I'll need to get a camera without built in leds, because 1) it's a giveaway and 2) the glare from the screen obliterates any image.
AJH
Can you not cover the leds with blu-tak?
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