Canon 350D modification
A standard Canon 350D has a filter over the sensor which absorbs infra red light. Unfortunately for astronomers, the filter removes a substantial amount of the red light that is given out by emission nebulae. It is possible to get the filter removed, and replaced by one with a less drastic cut-off. This webpage shows why it is best to get an expert to do it!

This change will make the camera unusable for ordinary purposes. For this reason, I bought another 350D on Ebay and sent it off to Astronomiser to have a filter change. In less than 48 hours the camera was back, and the two pictures below show the difference between the two filters.

Hopefully the skies will clear soon and I can try it out properly.
Canon filter Baader filter

This spectrum picture (from shows how much more is gained by removing the filter.
If the filter is not replaced by a Baader filter even more deep red light can get to the sensor, but the difference is unlikely to be visible in light polluted regions. The Baader filter also keeps dust from landing on the sensor.

The important wavelength for astronomy is the Hydrogen Alpha line 6563 which is almost completely removed by the Canon filter.
  Unfortunately light pollution is mostly Sodium 5893 which is also going to be boosted. It may be necessary to use a CLS pollution filter...