[Jan-Erik Skata] recently had to perform surgery on his Canon 300D since the secondary mirror would not raise up (and if manually locked wouldn’t autofocus). His repair guide is good; you may remember his focus screen replacement. The thing I found really interesting was the site he referenced for his disassembly: Gary Honis’s Canon Digital Rebel (300D) Modification. Gary removes the IR cut glass from inside the camera and replaces it with a piece of clear glass. He then shows how to setup color correction and confirm that autofocus is still working correctly. He’s even got a mockup for how to add peltier cooling to the CMOS chip.