我不能完全同意二位的意見。我同意就一台固定的數碼相機來說，它的信噪比是固定的我們沒法改變它。但是通過downsize from 8mp to 5mp，我可以同時減少信號和噪音（因為信噪比固定麼）。我不care減少一些details，5mp is more than enough，我覺得噪音也會有相應的減少,which I'd be very happy to see.

我正在考慮拿下Canon S5 IS(new Costco price is irresistable)，noise is a big concern. How I hope S5 would stay with the original 6mp on S3 or even 5mp on S2! But I guess Canon is too smart to realize that there are consumers like me who'd care about the actual IQ more than the boasting of useless high MP, sigh...

我拿到S5以後會自己比較一下8mp和5mp或3mp的噪音水平。謝謝二位的inputs.