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Thursday, 7 June 2012

Infra Red Night Image Quality and Illumination Range

Fig 1. 6210MC - Daylight reference image at ford
River Ford Site.
I chose this site to illustrate image contrast because of the temperature range it represents from very cold water (black) to the badger's body heat.

The tree to the right of the waterfall has retained a fair amount of heat whereas the rock face to the left is much cooler.

Figures 2 to 2b show the difference an equal change less (2a) and more (2b) in contrast makes. Less contrast equals more information within the limits of the technology.

Fig 2.  Badger drinking at ford. Normal contrast straight from camera.
The badger is 14 feet ( 4.3 metres ) from the camera and the tree bole is about 20 feet ( 6 metres )
Fig 2a.  Less contrast equals more visible information, digital noise accepted.

Fig 2b.  More contrast looks prettier but loses information.

Fig 3. 6210MM - Daylight reference image at badger sett
The next two image sets illustrate practical night range up to about 20 feet (6 metres) with these 940 nano meter infra red arrays. You can almost double the distance with the 850nm array which shows a red glow, visible when you look directly at the camera.

Badger Sett.
The badger's nose is pointing down into one of the sett entrance holes which is about 11 feet
( 3.4 metres ) from the camera. The trees behind the badger are about 20 feet ( 6 metres ) from the camera.

Fig 4.  6210MM - Night image at badger sett. This image may be soft and noisy but it also contains a lot of information.

Fig 5.  5210A - Daylight reference image at badger latrine.
Badger Latrine.
Fig 6.  5210A - Badger using latrine.
The badger in Fig 6. is 9 feet ( 2.7 metres )
The tree far left is about 19 feet ( 5.8 metres)
Fence posts fading away into the distance are faintly visible up to about 50 feet ( 15.2 metres )

I always try for a camera to subject distance of around 10 to 15 feet with small to medium sized animals although it's good to get closer when I can make it work. Much further away makes identification progressively more difficult, not entirely because of lack of illumination; but also because of the short focal length of the lens.

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This web site is about the wildlife, particularly the mammals, of the Glen Affric National Nature Reserve area in the north west Highlands of Scotland, UK; and the equipment I use to search for them, which is chiefly trail cameras.

I provide a technical support and parts service for the Ltl Acorn range of cameras and the income from this provides for the upkeep of this site and the purchase of cameras for my own surveying.

I hope you find the site useful and informative; and please contact me if you have any questions that I haven't already covered.