It is over two years since I published my results concerning the breakthrough modifications to a SC long exposure toucam webcam which finally cured all the problems relating to amp glow.....

Direct bias amp off modification for long exposure webcams

This was an interesting period. Steve chambers was showing off some rather fine dark frames from the then new Artemis 424 camera. This got me thinking... and asking a lot of questions from Steve.

All CCD chips that we use in astrophotography have varying amounts of electrical gubbins alongside the imaging chip. Most of these are to do with amplification of the charge stored on the CCD chip. Now, due to some effect, these components glow very slightly. You can see it on any DSLR. Put the lens cap on and take a 5 minute exposure at ISO 800. You'll see red bits down the side. This is glow from the on-chip electronics. In webcam astrophotography we called it "amp glow".

This "amp glow" limited the faintness of targets for our long exposure webcams . In fact, it was more an issue than light pollution was - at least for me.

We already had some rudimentary methods for reducing this glow. This were based around lowering the supply voltage to the CCD during exposures. Whilst this reduced the amp glow, it still left and uncomfortable amount of residual glow. Proper astrophotography CCD cameras didn't have this problem, so clearly they were doing something we weren't.

This "something" was supplying the bias voltage to the chip separately. The details in are my main direct bias amp off article but in the end I made it work.

Over the last couple of years or so since then I've always had a steady trickle of people enquiring about the mod - but because it came towards the end of the great astrophotography camera revolution, takeup of the mod wasn't very high.

These days it is very easy and cheap to acquire a fairly decent astrophotography camera, such as the ATIK 16IC designed by Steve Chamber. The need to modify a webcam to get a cheap foothold in the ccd camera market is no longer a requirement. Mind you, a black and white chipped long exposure webcam still makes a stunning guidecamera.

philips toucam circuit board