Q: Is there anyway to hook up a separate iSight camera which has firewire to another type of connection such as usb?

No, the Firewire and USB protocols are not compatible.

Not to USB, but if the "another type of connection" is Thunderbolt, you can use a Thunderbolt to FireWire Adapter

Message was edited by: EZ Jim

Mac OSX 10.10.4

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P.S.  michael -- You will also need either a Firewire 400 (six pin) - 800 (nine pin) cable or a 400-800 adapter to connect your old FW400 iSight to your Thunderbolt adapter or FW800 Mac.  Many other brands are available.  See your computer or electronics retailer for locally available choices.

Message was edited by: EZ Jim

Mac OSX 10.10.4