Hello Steve,
They are completely different cameras based on different approaches.
Your external iSight is a Firewire camera with built-in mic and auto focus.
Built-in iSight is a fixed-focus, USB video camera and no mic. All Macs that currently have built-in iSights also have separate built-in mics, and those mics are used with the built-in iSight when needed.
There are practical differences, too. Built-in iSight does not require connections, cables, mounts, and the attendant clutter and opportunity for problems associated with external cables, mounts, and connections. This seems to me an especially big advantage for mobile Mac users. However, if your built-in iSight fails, your whole computer needs to go to the technician for repairs. Of course, you cannot move a built-in iSight from one Mac to another or easily aim it at a different subject without moving the entire Mac. Moreover, I know of no way to mount accessory lenses. For example, external iSight users can add accessory wide-angle lenses to increase their camera's field of view as explained in
Mounts For Your iSight.
As is normal for different digital cameras, images from the two cameras are very different. Which you like better will likely depend on personal taste and may vary with subject matter and lighting conditions. To remove as many variables as possible, I made the following comparison image showing the same subject in the same location during the same video chat using the two different cameras (internal vs external iSight) on same iNtel iMac Core Duo. You can see some of the differences in color balance, sharpening, and contrast settings used by the two cameras:
Both external and the first built-in iSights were VGA (640x480) resolution cameras, but
this article asserts that some of the newer MacBook Pros offer 1.3 MP cameras as compared to the original 0.3 MP sensors. Depending upon the controls exerted by the
various software applications used to operate your iSight, resolution differences may or may not result in any noticeable difference to the user. If you contemplate using Windows apps on a new iNtel Mac, note that some MSN Messenger for Windows users report that their images are grossly and uncontrollably zoomed-in when using the new MBP built-in iSights with the Windows software.
If you want to continue to use it, your external iSight will work with a new iMac, too.
Please let us know if you need any other info before you can mark your topic "Answered".
EZ
Jim
PowerBook 1.67 GHz Mac OS X (10.4.10) G5 DP 1.8 External iSight
