This page describes the way in which a Philips Toucam Pro (aka Toucam 740) webcam was modified for use a telephoto webcam. The procedure also works for the Toucam Pro II (aka Toucam 840), which has an apparently identical PCB. In this example, the modified camera is fitted with a 50mm lens, giving approximately 7x magnification.
This method involves removing the Toucam PCB from its plastic case and installing it in a larger aluminium case, which has room inside for filters. The Toucam PCB seems to be quite robust, but there is a risk of destroying it during these modifications - proceed at your own risk.
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Completed camera
With lens removed
Note filter-holder and use of black insulating tape
With filter-holder removed.
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- Carefully dismantle your Toucam and extract the PCB. Optionally, remove the onboard red LED. This is located at the opposite end of the board from the microphone. Light from the LED will degrade low-light performance. The LED may be removed with a soldering iron or a sharp knife.
- Find a suitable aluminium box. The box used here is a "Bimbox 5007/17", which is available from Maplin Electronics as product DCM5007. This box is deep enough (56mm internal) to encompass the focal plane of 35mm lenses. Also, the lid is 2-3mm thick, which is a good match for the mounting ring of the Pentax K-mount lens used. Lenses with other mounts may require different boxes.
- The first machining task is to cut the hole for the lens in the lid of the box. This can be done with a small power drill and a hand-file as the material is quite soft.
- Once this has been done, put a few layers of dark-coloured insulating tape on the inside of the lid to remove any play between the lens and box.
- Drill an exit hole for the USB cable and protect the cable with a grommet
- The completed camera will be quite heavy, so adding a tripod mount is a good idea. This can be made by fixing a 1/4" BSW steel nut to the inside of the box with some aluminium plates, and drilling a 7mm hole through the case for the tripod screw. In the photographs on the left, a Slik quick-release platform has been attached, to reduce wear-and-tear on the tripod mount.
- Obtain some plastic sheet, preferably in a range of thicknesses from 2-7mm. Synthetic kitchen chopping boards are a good source, and much cheaper than sheets of engineering plastic.
- Cut a recess in the plastic sheet to accommodate the PCB, and drill some small holes for the tiny PCB mounting screws. Attach the PCB to the plastic sheet.
- Drill holes in the base of the box for M5 (or similar) bolts, and also through the plastic sheet. Try to position the holes so that the CCD sensor is as close as possible to the centreline of the lens - this is where the image quality will be at a maximum.
- Assemble the camera and attach to the computer. Try to focus the lens on an object at an approximately known distance. The distance indicated on the lens' focussing ring will probably not match reality, or it may be impossible to obtain focus. To correct this, add spacers of 1-3mm plastic behind the main plastic sheet until an acceptable focussing range is achieved.
- If you want to image visible light, you should fit an IR-cut filter (shown) just in front of the CCD for optimum image quality. For near-IR or near-UV imaging, IR-pass or UV-pass filters may be used. These filters are quite expensive, costing nearly as much as the Toucam - it may be possible to recover suitable filters from old camcorders or similar devices. In any case, it will be necessary to fabricate a filter holder out of bits of plastic.
- Covering the inside of the box with matt-black tape or paint may improve image quality. Masking the area around the filter may also help.
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