K3's Software - K3CCDTools
"When I consider your heavens, the work of your fingers, the moon and the stars which You have set in place, what is Man that You are mindful of him?" -- Psalm 8:3,4

How to Connect 2 Webcams to a Single Computer

I usually use two Philips webcams (Vesta 675SC2 and Vesta Pro 680) for astroimaging. Vesta 675SC2 enables to take long exposure frames, Vesta Pro 680 serves as autoguiding camera. They are connected to a single computer with WinME operating system. Both webcams use the same device driver (it is common for Vesta 675-680 series).

Connection is a little bit tricky - because current astronomy video capture programs (including K3CCDTools) use Video for Windows (WfV) API. Newer webcams usually use WDM (Windows Driver Model) drivers. WDM is newer technology than VfW. It provides wider range of possibilities, but on other hand, older devices and PCI video capture cards use standard VfW drivers. Newer WDM devices are implemented to VfW through mapping, which provides backward compatibility for WDM drivers to VfW-based applications.

News! K3CCDTools 2 uses modern WDM video capture interface which enables to directly select required camera from the list.

After connecting 2 webcams to USB port, there is still only one video capture device listed in device list in bottom of Video Capture menu:

This is because both video cameras are mapped into single WDM device to VfW. You can select device no. 1. Then the first webcam found is activated and you can use it. In my case it is usually Vesta 675SC2.

When you wanted to activate the second webcam, run another instance of K3CCDTools. K3CCDTools is knows that it is a second instance, so no videocapture device is activated. When you look at Video Capture menu, you still see only one device. Select this device. Then VfW will try to activate the first webcam found. As it is already activated, VfW interface offers you to select another device, but device selection is "hidden" in Video Source dialog - Capture Source tab.

In video device combo box both webcams should be listed. Select the second webcam (in my case Vesta Pro 680). Activate Preview, Brightness Level Meter and you can work with the second camera.


If you want to change webcams order (e.g. Vesta Pro 680 in the first instance and Vesta 675SC2 in the second instance), you must choose required webcam in Video Source - Capture Source after running the first instance.


When you use 2 webcams at once and one instance of K3CCDTools is running with Long Exposure, then some lost (black) frames may occur. This is caused by higher USB traffic. New version K3CCDTools (from version above) can handle this problem and no frames are lost in Long Exposure mode.

The practical utilization of two webcams you can see here: Homemade GEM1 Autoguiding Setup
Look also at screenshot.

Back to Homemade GEM1 Autoguiding Setup

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Last Update: 03.03.2004