a brody wrote: ... Can I use the iSight camera of another iMac via networking that can only update to 10.7 in some manner in 10.10 or 10.7? ...
Not in any general way. While you could use Old Mac's iSight via iChat ➔ Messages for one way video to New Mac inside your LAN via Bonjour, I know of no way to use Old Mac's camera as New Mac video recording source for QuickTime, Photo Booth, iMovie, etc., software on New Mac.
Because you are an experienced Mac user, you might be able to use Apple Remote Desktop to control Old Mac's camera from New Mac, but you would need to be using Old Mac's software to control its iSight.
Unless you have the time and interest in developing such workarounds, I think Boomer's Mac-Compatible external webcam alternative is a much better option.
Regards,
EZ Jim
Message was edited by: EZ Jim
Mac OSX 10.11