Tag Archive for DealExtreme

Wide Angle / Fisheye Lenses

I wanted to expand the field of view of my D-Link DCS-930L cameras, which have a horizontal field of view of 45.3°.  I scoured forums for decent wide angle / fisheye lenses that aren’t too bulky or expensive.  Two top contenders are both available from DealExtreme.

First up, the Jelly Lens Wide Angle/Fish Eye Filter.  This is just a low-quality plastic lens, but as Dan says, never mind the quality, feel the price!  At just $2.63 each, I had to try one out for myself.

I quickly realized that the jelly material was not strong enough to hold the lens for long.  I wanted a more permanent adhesive, but didn’t want to risk damaging the surface of my cameras.  So, I punched a hole in the middle of a piece of 1.88 inch wide clear tape cut to 1.25 inches long, and positioned it over the lens area of a DCS-930L in landscape orientation so it didn’t block the microphone hole.  I then removed the lanyard and jelly from the lens, thoroughly cleaned it, positioned it over the camera’s lens area, and used hot glue to secure it to the tape.  It held firmly, but it can still be removed quickly and cleanly.

Even though the DCS-930L is only 640×480 resolution, there is a noticeable degradation in image quality with the lens in place, especially in the corners.  Still, for surveillance areas such as the dog house, I think it’s worth it to get the wider field of view (approximately 60° horizontal).  For more important areas, a better lens is in order.

Enter the 15mm Detachable 180-Degree Wide Angle Fish Eye Lens, also marked as an “FE-12.”  This is a surprisingly high quality glass lens for $16.75.  The metal casing has a built-in magnet at the base, and two metal rings with adhesive on one side are included with each lens.  The idea is that you stick a ring to a camera permanently, but only stick the lens to the ring when it’s needed.

Like the jelly on the jelly lens, the adhesive on the rings proved too weak to hold the heavy lens long-term.  A ring and lens stuck to the front of a DCS-930L slowly slid downwards over the course of a few days.  I once again made a rectangle out of tape and punched a hole in the middle, but this time I just stuck it over the ring to give it more support.  Even though this created a gap between the magnet and the ring, it did not seriously affect the holding strength.

A DCS-930L’s horizontal field of view increased to an impressive 90° with the FE-12 lens (no, not the claimed 180°).  This is the perfect angle for a corner-mounted camera, since minimal resolution is wasted on the walls.  Compared to the jelly lens, only a very slight decrease in image quality was apparent in the middle.  However, the corners were a bit worse, probably due to the more aggressive curvature of the lens.

The FE-12 lenses are conveniently skinny enough at the base to fit through the center of an Infrared 35-LED Illuminator Board Plate for 6mm Lens CCTV Security Camera mentioned here, allowing for a compact lens-board-camera sandwich.

Update (11/26/2011): DealExtreme now carries a Detachable 185-Degree Wide Angle Fish Eye Lens for Cell Phones and Digital Cameras, also marked as an “FE-18.”  The price is a fair bit steeper than the FE-12 lens at $24.30, but it brings the DCS-930L’s horizontal field of view to 117°.

I now have 3 jelly lenses, 6 FE-12 lenses, and 1 FE-18 lens.

Infrared LED Assemblies

My old composite video surveillance cameras have 6 IR LEDs built in.  The LEDs are small, and are only useful up to a few feet away from the cameras.  One particularly shoddy camera would overheat and shut down after being plugged in for a few minutes, so I had to disable its LEDs altogether.  Eventually, I decided to explore stand-alone IR LED assemblies.

My first purchase was a weatherproof, pod-shaped InfraRed Illumination Light for Night Vision (DC 12V 500mA)pod with 48 LEDs from DealExtreme.  All the LEDs are mounted directly perpendicular to the PCB, and right up against it, so the pod acts like a spotlight.  That’s not very useful for illuminating a large area.  Repositioning the LEDs isn’t a great option because of how recessed they are within the pod.  So, I unscrewed the front of the pod and secured a piece of wax paper to the inside of the glass cover to act as a diffuser.  This works fairly well, but is still not ideal.  The pod gets quite warm to the touch, so warm that the wax paper has melted onto the glass.  I keep an old computer fan pointed at the pod in an attempt to extend its lifespan a bit.

For more freedom to reposition the LEDs, I decided to try a bare IR LED assembly next.  I chose an Infrared 35-LED Illuminator Board Plate for 6mm Lens CCTV Security Camera from DealExtreme for a mere $3.84.  It is sold as a replacement for inside a security camera housing, but I intended to just stick it to the front of one of my cameras with foam tape.  Thus, I only had to worry about the size of the inner circular cutout, which is listed as 18 mm.  A word of warning: it’s actually 16.3 mm, so it does not fit my two oldest cameras.

To power the board, I got an AC to DC 12V 1A Power Adaptor with 5.4mm DC Plug – US Type (110~240V) from DealExtreme for $4.31.  It came with a barrel connector, but the LED assembly had a small header.  So, I cut off the barrel connector, unsoldered the header, and soldered the wires directly to the pads on the LED assembly.

Stock, the IR LED assembly had a beam much like the weatherproof pod.  However, I was able to wet the solder on the LEDs’ legs, raise them off the PCB a bit, and bend them outward.  I bent the 21 LEDs in the outer ring to approximately 20°, and 7 of the 14 LEDs in the inner ring to approximately 10° (I kept 7 in their original places to maintain good coverage directly to the front).  Now the beam is a little over 45° wide, which works well for my old composite video cameras, and my new D-Link DCS-930L cameras after a modification.