回复：请教行家: 新买的CANON SD870IS拍出的照片清晰度不够 (图)

For photos: possible cause - out of focus, dirt on lens or camera shake.

For video: it's fix pixels at the widest view (say 640x480 on my A710). The zoom is actually digital zoom on video only... so if the video just on the wide end is too small, get a camcorder...

Hope that helps.