How long a USB2 cable dare i run for a USB camera?

[Basil]

I have a basic USB2 camera from Microsoft, the sort of thing one might use on Skype. How long a USB cable dare i run, and if it were over say 20 feet does it need powering at the camera end? I want to use it temporarily to watch outside through a window about 25 feet or so from the PC, which runs Windows 7 64 bit OS. I see on Ebay powered USB cables up to 25 meters, but they mainly say PRINTER extension powered cables, can I use one of those? Thanks!

 

[samuria]

Between 3 to 5 meters is the limit depending on speed and power

 

[LMiller7]

The USB specs are 5 meters or about 16 feet for USB 2. That assumes good quality cables. To exceed 5 meters you can use powered hubs between cables but be sure that no cable run exceeds 5 meters.