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Sunday, 15 June 2014

Ltl Acorn 850nm, 940nm, 24 and 44 Infra Red (IR) LED arrays compared.

Fig 1:  5210A with 24 IR LED Array
Following on from my previous post which compared the FOV of the new Ltl Acorn 5310 standard and wide angle lens models, this post illustrates the differences in appearance and performance between the old and new infra-red (IR) LED arrays.

Up to now all the Ltl Acorn camera models have used a 24 LED IR light source as shown in figures 1, 2 and 3. Figure 1 shows the 5210A with 24 blue LEDs which emit light in the 940nm wavelength. These LEDs are covert and do not glow when operating.

Figures 2 and 3 show the 24 LED 850nm and 940nm versions. The white LEDs emit light in the 850nm ( nanometer ) wavelength and can be seen to glow red when viewed straight on during operation. They are visible up to 10 plus meters distance and although the IR light emission has double the range of the 940nm version they are not suitable for use in situations where the camera may be vulnerable if observed, such as security applications.

Acorn have now released their 5310 series cameras using their newly developed 44 LED array which doubles the night time light

Fig 2:  24 LED array at 850nm
Fig 3:  24 LED array at 940nm
range for covert use and figures 5,6,7 and 8 below illustrate this by comparing the results from each of the LED arrays.

Figure 4 shows the new Ltl Acorn 5310A 940nm version with the standard lens and the new 44 IR LED array

Fig 4:  Ltl Acorn 5310A
with the new 44 IR LED array.
The night time infrared images below show a significant improvement in both illumination distance and image quality when using the larger 44 LED array.

The images were taken at 12 MP and have been reduced in size to 1000 x 750 pixels using bicubic resampling. Otherwise they are straight from the camera and if you view them full size you can clearly see the improvement in image quality provided by the 44 IR LED array.

The range is looking down a fence line with two fences at 90 degrees to it. The near fence is at 8 feet ( 2.4 meters ) the bush near left is 15 feet ( 4.6 meters  ) and the far fence is at 55 feet ( 16.8 meters ). In figure 7 the bush to the left of the main fence line in the far distance is at about 70 feet ( 21.3 meters )

Figures 5 and 7 give a direct comparison between the 24 and 44 LED arrays

Fig 5:  Ltl Acorn 5210A ( 52 degrees - standard lens ) using the 24 IR LED 940nm array.

Fig 6:  Ltl Acorn 5210A ( 52 degrees - standard lens ) using the 24 IR LED 850nm array.

Fig 7:  Ltl Acorn 5310A ( 52 degrees - standard lens ) using the 44 IR LED 940nm array.
Fig 8:  Ltl Acorn 5310WA ( 100 degrees - wide angle lens ) using the 44 IR LED 940nm array.

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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.