OK guys, so I was asked a very good question:

Why does the 400D exibit more noise than the 350D?

Here is my answer tell me who agrees and who doesn't... (shooting in RAW)

You'll see noise much more in the blue and green tones of an image, more so than the red. If you look at the images you shoot you should notice more noise in the areas that are very colourful or those that are one bright colour (like a blue sky).

The 350D is better at handling noise than the 400D and the 300D is even better than the 350D.
The reason for this is that as the MP of a sensor increases so does it's ability to fit more detail into the pixels of the sensor. What this means in short is that the same sized pixels on a sensor in a 300D(6MP), 350D(8MP) and 400D(10MP) have to fit more light in and hence more noise is fitted in too.

You should also notice this with cellphone cameras too. If you take an old VGA camera phone (NOKIA) and then take one of their new 2MP camera phone and take the same image and compare them on the PC. You will see that the new image is more 'in focus' because is can fit more detail in as that's how it's programed. But the VGA picture will have much much less noise in it (actually nearly none) as the sensor is the same size in each phone, they've just been programmed differently.

What happens in ISO 100 and ISO 400 the sensor is programmed to read the same amount of light but at different speeds. So if you are shown 20 cards and asked to remember all of them in 2 mins (ISO100), that's easy and you'll do a good job of it. But if you are shown those same 20 cards and asked to memorise them in 30 secs (ISO400) you'll only be able to remember some of the cards. That's why there is more noise at ISO 400 - the camera is trying to 'fill in the blanks'.

Now if you think of the 10MP sensor of the 400D and the 8MP sensor (exactly the same size sensors but prgrammed differently) this is what is happening at each ISO. Let's think in ISO400 seeing as that's what we're talking about.
Using the cards again. Lets say the 8MP is worth 80 cards and the 10MP is worth 100 cards (in detail).
If you use the same settings (shutter and aperture) and apply the same rules as I discussed above, you can understand why the 10MP can pick up more detail than the 8MP.

So what is happening is the 10MP sensor sees 100 cards but can only remember 80 cards - takes a success of 80%.
However the 8MP can see 80 cards and remembers 70 cards - takes a success rate of 87.5%.
The gap is not big but the 10MP sensor has more 'gaps' the remember. So while you get all of the 80 cards that the 8MP can see (think of this as detail - and more detail means bigger prints) it also comes with more forgotten cards (think of this as noise).

I've attached photos in the following replies:

1st pic - 350D sensor seeing detail as 80 cards out of 100.
2nd pic - 400D sensor seeing detail as 100 cards out of 100.
3rd pic - 350D sensor seeing detail as 80 cards but only remembering 70 and 'filling' in pink areas with noise.
4ht pic - 400D sensor seeing detail as 100 cards but only remembering 80 and 'filling' in pink areas with noise.

Does all of this make sense? Or am I just a pathological rebel?

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