Philips Toucam Pro Models PCVC740K and PCV840K

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The Toucam promised (on the box) 1280 x 960 color resolution and fast USB download with no lockups! The resolution turned out to be interpolated - the CCD was actually a Sony HAD device with 640 x 480 pixels and a size of 3.6 x 2.7 mm. It is a common advertising ploy with webcam manufacturers to claim all manner of resolutions, but it is the resolution of the CCD chip that counts - not the output image resolution. However, it was a major step forward in both operation and image quality.

An essential feature of any webcam is manual control of the exposure settings. Surprisingly some early commercial astronomical video cameras did not have this. The Toucam has manual adjusters for exposure (longest 1/25th second), gain, brightness and saturation. It has an "auto" mode too, which is generally about right for the Sun and Moon.

As with any webcam the first hurdle to overcome is finding a way of connecting it to the focuser. The lens on the Toucam actually screws off so it was relatively simple to make a 1.25-inch adapter (see Figures 3.1 and 3.2). Such has been the explosion in webcam use for astronomy that several manufacturers are now supplying these adapters off the shelf.

Late in 2003, Philips released an upgraded version of the Toucam Pro II (Model PCVC840K), and there was much concern in the webcam fraternity that it would not be as good for astronomy. However, the camera is basically the same but housed in a smarter case. The sensor appears to be identical, i.e., a Sony 640 x 480 CCD and the software is still limited to a 1/25th-second longest exposure. On the downside the USB cable has been reduced to 1.5 meters long - half of what it used

Figure 3.1. Philips Toucam Pro II with 1.25-inch adapter replacing the lens. Note on the rear of the original lens is an infrared block filter.

Figure 3.1. Philips Toucam Pro II with 1.25-inch adapter replacing the lens. Note on the rear of the original lens is an infrared block filter.

Figure 3.2. Toucam Pro II with 1.25-inch adapter. Note that the infrared block filter from the rear of the original lens has been refitted into the adapter.
Figure 3.3. Solar closeup. Taken with a Toucam Pro II on a Celestron C8 at prime focus (2032mm focal length) and a Thousand Oaks solar filter. One of the problems with solar imaging is seeing the computer screen in broad daylight. A black cloth or hood helps.

to be. A USB extender cable will therefore generally be required (see Figure 3.4). The annoying red LED is also there, and the price went up slightly. Otherwise it was business as normal.

For centering and reaching focus it is best to have a wide-field eyepiece and have it approximately parfocal with the webcam. This can be achieved by taping the barrel of the eyepiece so it slides in to the precise common focus. Finding an object is fairly simple using an eyepiece and then switching over to the Toucam without disturbing telescope pointing. This way it will be close enough to focus to generate an image on the computer screen.

Having used an adapter and realized the power of the Toucam, I had more ambitious plans, and a second camera was purchased. My idea was to totally dismantle the camera and mount it on the back of an old SLR camera body. This would provide:

• Viewfinder for easy location and centering of bright objects.

• Visual setting of the approximate focus position.

• Camera lens mount for easy attachment of adapters or lenses.

The camera comprised a single circuit board with the CCD mounted fairly centrally. An old Pentax camera body was available for mounting the circuit board, which just needed the microphone disconnecting as it would have prevented it being mounted near to focus. It was simply spot epoxied into place and sealed

Figure 3.4. Toucam Pro II attached to the visual back of a Celestron C8 - the base of the webcam has been unclipped. Due to a shorter USB cable the laptop PC has to be close to the telescope. If you need to be further away, use a USB extender.

Figure 3.4. Toucam Pro II attached to the visual back of a Celestron C8 - the base of the webcam has been unclipped. Due to a shorter USB cable the laptop PC has to be close to the telescope. If you need to be further away, use a USB extender.

with silicone. After 24 hours it was ready for use (see Figures 3.5 and 3.6). I have subsequently mounted 3 more on the back of SLR cameras for friends. On these later conversions, to get the chip at focus so camera lenses can be used, I have ground recesses into the camera's film rails so the circuit board can sit lower. I

Figure 3.5. "Pentax" Toucam - front view with the camera mirror raised.

Figure 3.5. "Pentax" Toucam - front view with the camera mirror raised.

Figure 3.6. "Pentax" Toucam on 16-inch Newtonian. The CCD could be regarded as "air-cooled," which does improve performance!

aim to get the chip either at focus or fractionally inside focus. This way lenses will always reach infinity focus.

First testing with the Pentax Toucam was a revelation. A camera cable release was needed to raise and lower the flip mirror but everything had gone well - the chip was almost exactly central and near enough the right focus position. The viewfinder works brilliantly, enabling easy centering of objects on the CCD.

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