We put these two cameras through their paces with noise tests shot at the same time, same lens, same tripod and same subject.
Comparison using our low complexity subject for daylight shooting
100ISO
350D
400D
At 100ISO there is not much in it, though the 400D is softer and has lower contrast.
200ISO
350D
400D
Pretty much the same as at 100ISO
400ISO
350D
400D
Same as at 100ISO and 200ISO. Perhaps slightly higher noise for the 400D, but not by much.
800ISO
350D
400D
If anything, slightly less noise than the 350D.
1600ISO
350D
400D
There is slightly less noise on the 400D than on the 350D, however if you boost the contrast on the 400D image to match the 350D’s, the noise would be a little more noticable.
Test continues in Part 4 with the night test and final conclusions.