Since the Canon Rebel is the most common camera used between enthusiastic astrophotographers I’ll try to suggest some good links of step-by-step tutorials which guide you thought the process.

1. Canon Digital Rebel (300D) Modification
   Good tutorial with sample images before and after modification. For Rebel (300D).
2. ash’s Modified Digital Rebel XT Page
   Very nice tutorial for modification of Rebel XT (350D). I have done modification of my Rebel XT with this guide and he survived the operation!
3. Canon Digital Rebel XSi (450D) Modification
   Good guide with pictures and everything well explained for Rebel XSi (450D).
4. Canon Digital Rebel (300D) Peltier Modification
   Guide how attach Peltier cooling element into Rebel. Works good for long-exposure astrophotography.
5. Another Digital Rebel XT (350D) Modification
   Just another Digital Rebel XT mod. Maybe someone finds it useful.

For the end I am presenting one of my images after the modification. The Veil Nebula, NGC 6992:

The Veil nebula (NGC 6992) @ Primož Cigler

Only 10 years ago we’d found astrophotography as pretty expensive. The reason is that the cameras for serious work costed a fortune! Anyway, it was Canon 300D which completely changed everything in 2003. Now it’s only 6 years from that and we all are using DSLRs for astrophotography. Let’s take a look at it:

Canon 300D was the first very good DSLR. It’s price wasn’t too high and the picture quality was great comparing to other cameras. Firstly became very popular for daylight photography but very soon some astrophotographers figured out that it’s possible to get very nice picture with it. The main advantages are that we can set the high ISO level without suffering too much noise, we can always check the focus on LCD screen, we get digital images which we can post-processed with the computer and many more.

But that wasn’t enough for some of astrophotographers. If we take long exposures (above 1 min) that means that the sensor is on all the time and the temperature increase. And when the temperature increase the noise becomes annoying on pictures. This problem can be solved with cooling and some astrophotographers started to modify their Rebels to improve the image quality.

It’s not only the temperature which makes 300D worse that it could be. There is also a filter in front of the CMOS sensor which blocks almost all the light in H-α part of spectrum. That’s the problem because almost all the nebulas in the space consists of this element and when we are capturing we loose almost all the light we want. It’s like looking at Andromeda’s galaxy with sunglasses.
This problem can be solved also. All we have to do is to remove the filter in front of CMOS and replace it with some other or clear-glass. The only way to do this is to disassembly our camera or let someone do that.
For example, the Hutech is the company that produces replacement filters, they can replace filter instead of you, and what is more, you can buy the modified camera at them.
However, Teleskop-Service offers the same in Europe.

On the end I’m presenting you one picture that was captured with “the king of DSLRs in astrophotography”, Canon Rebel/300D/Kiss.
It’s picture of Veil nebula which is located in Cygnus. The exposure was 12 times 5 minutes post-processed in Photoshop and Iris. The telescope was Takahashi FSQ-106 and mount Celestron CGE. I’m sure you like it!

Veil Nebula @ Marjan Žagar & Primož Cigler