[corinne3]

could anyone tell me the difference between optical zoom and digital zoom.as the new canon ixus i has no optical zoom as compare with ixus 400.is it a big deal.it is my first time to buy a DC.which one is better?ixus400 or ixus i? thank advance for your answer!!

[老叟]

Optical zoom:resolution unchanged!!
Digital zoom: resolution changed,quality downgrades!!
Simple as that !!

[fwho2000]

For example,
Considering a 400 M pixel camera,
if using 3 x optical zoom, the resolution will become 400 /9 , about 45M pixel, if you use a 4x optical zoom, it will become 400/16, about 25M pixel.

see ?