UPDATE, May 2017.
I have been commissioned to make another of the items described below. This one will involve a table-top box, on which the TV will sit, and to which the arm holding the video camera will be attached. The precise design will depend on the details of the video camera I have ordered, which might not arrive until mid-July. Details will be published on this blog in due course.
Introduction: two projects to help the visually impaired
This is the second of two posts on projects to help the visually impaired, motivated by the desire to assist an elderly relative with macular degeneration who is not computer-literate. Anything to help her had to be simple to operate and not involve computers. A further restriction was that it should not be too expensive. (You can find the first post here:
Audio books for the visually impaired: cheap alternative to special MP3-player.)
Project Two: a cheap way of achieving huge magnification
Background: TVs and video cameras
Many people these days have TVs with AV input sockets which accept jacks from video devices, and many video cameras come with cables and jacks which fit. When such cameras are plugged in, to the AV1 or AV2 sockets, the appropriate input source is selected on the TV, and the camera is switched on, the TV screen effectively becomes the camera’s viewfinder, showing whatever the camera is pointing at.
However, most inexpensive video cameras do not have macro capability, i.e. they cannot focus on objects near the lens, which means they are not of much use for reading newsprint and the like.
Even if one has a video camera which can focus on objects a few centimetres away, the least movement renders the image unstable and/or out of focus, and therefore impossible to read. Given that people will sometimes want to read very large items with small print, such as newspapers, any means of mechanically supporting a camera must not get in the way of such items, or make it difficult to move them.
The solutions: attaching magnifying glasses to the camera and attaching the camera to a fold-down boom
I found a cheap video camera through Gumtree. It was a Telefunken TVC-500 5 MP, almost brand new, but going for less than a sixth of its new price, possibly because the manual was missing – what a bargain! This camera has a 4x zoom.
I then looked for good magnifying glasses, and found this one in a local discount store (Game in South Africa, the country I was visiting at the time):
I then played around with this and other old magnifying glasses and found that by holding the one I had bought and a smaller one tightly together in front of the camera’s lens I could get the camera to focus on objects less than 20 cm away, making significant magnification possible.
Next, I wound tape around the handles of the magnifying glasses, and then used wire and an old hose clamp that happened to be handy to attach the lenses to each other:
The next step was to attach this magnifying glass unit to the camera. I found that the best focus was obtained with the lens of the large magnifying glass virtually touching the front lens of the video camera.
First I mounted the camera on a piece of hardboard, attaching it to the hardboard by drilling a hole and then bolting it on using the hole on the camera meant for a tripod. (Fortunately I found an old bolt of the right diameter and threading parameters. It was a bit long however, so I put several washers on it, including a rubber one to give the attachment a bit of resilience.)
Then I made a little rectangular frame from a strip of wood with a square cross-section of sides of about 15 mm. This was attached to the ‘front’ end of the hardboard, around the camera’s lens, such that it sat virtually flush with the front of this lens. I used both glue and small screws for this, drilling pilot holes for the screws so that the wood would not split. I then attached the magnifying glass unit to this frame. In order to do this, I played around with pieces of cardboard, cutting various shapes until I had fashioned two odd-looking shapes which would hold the frame of the large magnifying glass flush against the wooden frame around the camera lens when screwed to this frame. I used these pieces of cardboard as templates to trace out their designs onto the thin plastic of the lid of an old ice cream container. I then cut out the shapes from his ice cream container and screwed them into place. They held the magnifying glass unit in place very well.
The next thing I wanted to do was to attach the camera unit to a boom (made of the same 15 x 15 mm square cross-section wood I had already used), such that it could be held in place the perfect distance above a small table on which reading material could be put. (Of course, it also needed to be such a length that the camera would remain within the length of the connecting cable from the TV, when plugged in.) While most reading material would be thin, I wanted to allow for the reading of thicker items, such as telephone directories and food packets. I found an empty box, which could be put on the small table to raise thin items and removed when thick items were to be viewed.
I then attached the boom to the camera, in the way that can be seen in the photographs, and attached the boom to a bookshelf next to the TV. The camera can be rotated slightly thanks to a wingnut arrangement. It’s easier for you to understand this from the photographs than for me to explain it in text!
I drilled a hole about 20 cm from the bookshelf end of the boom such that it would fit loosely around a screw I drove into the side of the bookshelf. The boom then rotated around the screw and could be lowered into position such that the camera was above the reading table. In order to hold it in the right position, I screwed a small piece of wood to the bookshelf to act as a stopper for the boom.
The next step was to tie a small piece of cord to another bookshelf so that it could be looped around the protruding wingnut and hold the camera out of the way when not is use.
The final set-up works perfectly. Without the camera zoom it gives 12x magnification. When the zoom is fully activated (4x) it gives 48x magnification.
My visually impaired relative can now easily read small print. All she has to do (if she is not using the zoom) is switch the camera and TV on (assuming the TV is left switched to AV1), position the table and what she is reading, and lower the boom.
The total cost of this (as I had tools, scrap wood, and other materials to hand, and the TV was already there) was R350 for the camera + R99 for the new magnifying glass, which is less than £30.