I HAD A 50D AND NO ISSUES AND HAVE SINCE GOT THE 7D NO PROBLEMS WITH LONG EXPOSURE.
AS FAR AS CANON SAYING IT WAS NOT DESIGNED FOR ASTRO WORK ,THE CAMERA IS DESIGNED WITH A BULB FUNCTION AND NOISE REDUCTION FOR LONG EXPOSURE AS WELL AS CANON SOFTWARE TO PERFORM THESE FUNCTIONS HOW DOES IT MATTER IF YOU ARE USING IT IN THE DAY OR NIGHT MAKE A DIFFERENCE.
I WOULD BE GOING FURTHER WITH THIS WARRENTY ISSUE.
HAS IT BEEN MODIFIED--I.E. FILTER REMOVED ,THEN KISS YOUR WARRENTY GOOD BUY.
MARK