Apparently the A2100 has the picture size set to 640x480 (1/3 of a megapixel).
That is fine for emailing but it is bad if you ever plan to print the picture.
The SX210IS is set for maximum size (14.1 megapixel).
That is fine for printing a photo.
It is too big for emailing.
You can set the SX210IS to a smaller picture size but I don't advise it.
For a very good 4 x 6 inch print, you need at least a 3 megapixel image.
For an very good 8 x 10 inch print, you need at least a 7 megapixel image.
Before you ask;
Yes, with software you can resize a 640 x 480 image to a larger size for printing.
But, you will get a poor result.
I suggest you continue to resize your pictures for emailing.
I have two Canon camera's. One is A2100-IS & Two is SX210-IS.
When I take a photo of an object with the A2100-IS and e-mail it, the size is 640 pixels, 640x480 no problem here.
If I take the same photo with the SX210-IS and e-mail it, the size is 4320 pixels, 4320x3240. Much too large for e-mail. Everything on the SX210-IS must be "Re-Sized" before e-mailing.
Any help with this problem?