Wednesday, June 9, 2010

Does it really have to cost so much: Custom building an electronic magnifier.

By Luke Hsieh, Assistive Technology Advocate, Community Access Center, Riverside

When my supervisor saw the 13-year-old webcam that I have lying around my office, he asked me if I could turn it into an electronic magnifier using a Windows computer and USB port. The technology involved really isn't rocket science. Bierley is selling a USB based MonoMouse magnifier for approximately $200, so my response to him was, "Besides optical zooming and autofocus, the rest is just software." That statement effectively commenced the experimental project codenamed Webcam. (I told you it wasn't rocket science!)

My choice of webcam fell on the Logitech Webcam Pro 900, one of the higher end webcams that has a 4x optical zooming capacity and autofocus. It even comes with a Carl Zeiss lens and a built-in microphone. They sell for around $70 each.

The prototype was designed so the webcam would hang on a stand to be used as a CCTV. The problem with the prototype was that 4x optical zooming simply wasn't enough for it to function as a CCTV Magnifier and purchasing a battery powered digital camera with higher optical zooming capacity would cost $250.00 or more. (Merlin costs $2700.00 for a reason.)

I knew I wanted autofocus for a reason! All I had to do was bring the camera closer to the paper by wedging the camera into a circular lunchbox and poking a hole on the other side for the USB cable to go through. The prototype mimicked the Bierly Monomouse instead of the CCTV.

The next question was which software to use for color inversion. After trying out more than several trial versions, demo versions, and free versions of video software, I chose Debut Video Capture made by NCH Software, an Australian company, which costs approximately $39.

So the end bill for this exercise is $70 for the camera, $39 for the software and $2 for the lunchbox. Of course, if one has the money, it's better to buy professionally designed video magnifiers like Merlin, Jordy, Ruby, etc. However, this exercise does show how people with limited resources can build their own electronic magnifier with color inversion for a little more than $100.00.

Have you built your own assistive technology? Whether you have built a high- or low-tech device, we want to hear about it. Please share any of your tips or tricks in the comment section below.


  1. This should be called to the attention of the Lions Clubs. They might prefer using their members skills and labor in making CCTVs to raising funds to buy the expensive kind.

  2. I had considered this myself for my grandmother. I felt the computer was too big a hurdle, and used a wireless "spy" camera purchased from e-bay for ~$30 to build a low-cost TV based magnification setup. The camera has a threaded barrel for focus adjustment, and can be used to set the relative zoom. I mounted the camera to a wooden block with legs made from coat hanger wire to hold the camera a fixed distance from the page. It was a bit awkward at first to keep straight, and needed quite a bit of light. I see there are some now with LED's built in. PS, cover the microphone with tape for privacy.