A simple hardware modification allows the modest web camera to detect faint targets like galaxies and nebula by using a computer to externally control the camera’s exposure time. It involves severing some electrical connections and then soldering wires onto the camera’s circuit board in an attempt to bypass the web camera’s internal clock and image processor. This modification allows the web camera to take full advantage of its far more sensitive sensor — a CCD — to be used as an imaging camera, or as a dedicated guide camera for autoguiding purposes. In this article, I will describe how a Logitech Pro 4000/Logitech Pro 3000 can be modified for use in long-exposure and deep-sky photography.
Below is a comparison between two images taken before and after the modification. An unmodified webcam (see left image) can only be exposed for a maximum of 1/5 of a second, too short to register an image in an extremely low-light situation (e.g., a room with the moonlight shining through a window as the only light source). A modified camera however (see right image), may be exposed for as long as desired (in this case, for about 60 seconds), and thus capable of collecting enough light to reveal ample amount of details. This newly-added feature is very useful for deep-sky photography where exposure of a few minutes or more is not uncommon.