Latest update 99-6-2     

Astronomical use of the "Blaster Webcam II" PC video camera.


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In November 1998, I bought a "Blaster Webcam II" PC video camera intended for use in internet video conferences. There are now several cameras like this one available on the market I bought the Webcam II just because it was the cheapest available in the shops nearby. The Webcam cost here in European in November 98 about $110. An other well know PC video camera used successfully behind a telescope is the QuickCam. These type of digital video camera have no video connection but are directly connected to the parallel port of the PC. There are also USB port version cameras are on the market. Even with compression technics the number of frames is limited and only at the lowest resolution real time video is achieved. For the higher resolution it is too slow. However they are very interesting for astronomical purposes. The size of the camera is about 7 x 7 x 7 cm or 3 x 3 x3 inch.

The 5 volt power supply for the camera is coming through the keyboard connection. For this an additional cable is connected between the PC and the keyboard. The video is directly transferred to the PC using the parallel port.

Here are the Webcam specifications:

Resolution: 352 x 288 maximum (Others are software enhanced)
Colour and for low resolution 176 x 144 up till  30 frames a second.
Sensitivity:  15 Lux @ 7.5 fps
Cable length 2 meters.
Windows 95 software.
The size of the camera is about 7 x 7 x 7 cm or 2,5 x 2,5 x 2,5 inch.

Before the camera can be used, the wide field lens should be removed. Under two of the four rubber legs are small screws hidden. After removing these screws, the bottom can be shifted and removed. After opening the camera the camera the lens can be screwed out completely and taken away.

The CMOS chip is like all CCD cameras small. Something like 3 x 4 mm. Mounted behind my ETX telescope (Focal length 1250 mm) the result is a field of view of about 7 arc-minutes. The field of view you will get when looking through a plössl of about 6.5 mm. So very small. I was able to fit it behind the #64 camera adapter for the ETX by using the thread intended for a camera standard, a piece of metal and two tie-raps. See drawing:


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With a Shapely lens screwed between the two parts of the #64 adapter, I was able to increase the viewing field till about 15 minutes. 15 Minutes is half of the diameter of the Moon.

The field of view is very small. A normal photographic film of 24 x 35 mm has a much larger filed then the tiny chip of about 3 x 4 mm. I had great difficulties finding the planets Jupiter and Saturn. I also have the impression that the light sensitivity is not enough for Saturn but managed to get enough light with the converting Shapely lens. The Sun and Moon are a much easier target.

I tried to get a picture of M42 but the sensitivity is just too low. So only pictures of the Sun, Moon and the planets can be taken.


Saturn. The camera was just sensitive enough to get Saturn. Select minimum contrast and maximum intensity:

This shot was made through an open window of my house, close to my heavy tower model computer. (In fact the ETX was standing half outside window frame) It was freezing cold, a few degrees below zero and the temperature in the room was about zero. The sky was very clear and due to the equilibrium between the room and the outside air temperature, the conditions where very good.


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Jupiter:


jup-9811.jpg


Some nice examples of a sun spots:


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Here is a picture of the moon. Very low, just above the horizon:


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Here some other moon pictures:


moo98112.jpg


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Here is a picture of Mars made with the LX10. It is the best result of a few clear days. The biggest problem is to have a stable atmosphere. Most days, the atmosphere/air is just to unstable. During the bad days, you I could recognize that mars is a planet and not a point source, but it looked like somebody was holding a candle just below the front of mine telescope:

Here is the best ETX picture of Mars using the webcam video camera. Compare it with the LX10 result above.