Alexg Posted January 19, 2006 Posted January 19, 2006 Looking at a dennard 880 50Watt IR lamp. It has a 715nM filter, how much of a glow will this give off? Thanks.
Guest ALSEC Posted January 19, 2006 Posted January 19, 2006 Looking at a dennard 880 50Watt IR lamp.It has a 715nM filter, how much of a glow will this give off? Thanks. Can't remember which way round it works (haven't done any CCTV for ages!). I seem to remember that 700 range is covert, 800 is in the middle and 900 is overt?
Brian c Posted January 19, 2006 Posted January 19, 2006 Can't remember which way round it works (haven't done any CCTV for ages!). I seem to remember that 700 range is covert, 800 is in the middle and 900 is overt? Yes that's right. 950nm is covert. 715nm will be visible (similar to a traffic light, according to Derwent) If you don't know......ask.
Service Engineer Posted January 19, 2006 Posted January 19, 2006 Wavelengths_for_Colors The above link is a good resource on the subject of what the human eye can see. 715nm - Emits a cherry red glow. Red glow will reflect off a wall to about 5 feet. A cherry red glow can easily be seen when looking at the light.830nm - Emits a dull red glow. No red light visible from reflected light. A dull red glow can be seen when looking at light. 1000nm - When bore-sighting (viewing directly into beam) in a completely dark room from a few feet, you can see a very faint red glow. Otherwise, the light produced is completely invisible to the human eye. Most night vision devices (NVD), can only see to about 880nm. The 1000nm will work but not very well with these devices. When complete covertness is required, the 1000nm is the best option. ........................................................ Dave Partridge (Romec Service Engineer)
Nova-Security Posted January 19, 2006 Posted January 19, 2006 850nm is the start of invisable light. www.nova-security.co.uk www.nsiapproved.co.uk No PMs please unless i know you or you are using this board with your proper name.
Alexg Posted January 20, 2006 Author Posted January 20, 2006 Thanks, Will the majority of B/W cameras work ok with 715? I've currently got a 830 lamp and the camera hardly sees it.
amateurandy Posted January 20, 2006 Posted January 20, 2006 Visible light is normally considered to be from around 400nm (Violet) to around 700nm (Red). Infrared then extends from 700nm to around 1mm where it overlaps into microwaves depending on whose definitions you use.
Andy D Posted January 21, 2006 Posted January 21, 2006 Thanks,Will the majority of B/W cameras work ok with 715? I've currently got a 830 lamp and the camera hardly sees it. It depends if the b+w camera is IR sensitive?,if it can see somthing from th 830nm then it should be better with a 715nm light
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