You can use common format drive.. although unfortunately about the only one available is FAT32 which is not at all a great format.
Using network shares is much better way to go.
You can plug the drive with all the pictures into a computer, a PC in this case of course, and share that drive with the network. The Mac can then access the drive, read and write files to it, over the network. FIle sharing on the network is offered with a few different protocols, but both Mac and PC can talk windows SMB type.
Same btw with a disk formatted on the Mac to native Mac standard HFS+ and plugged into the Mac and shared with the network. A PC and read and write files to it via SMB sharing. Simply because it is shared on the network.
Now a Time Capsule is a wireless router with a hard disk in it. The file sharing side is handled in SMB windows type and AFP which is a Apple Filing Protocol.. see http://en.wikipedia.org/wiki/Apple_Filing_Protocol
The Mac can talk both AFP and SMB to the TC.
The Windows computer can talk SMB to the TC. So they have a common method to access files.
You can then plug a USB drive into the TC.. but it should be Mac formatted, HFS+ (in the mac disk utility this is called
Format : Mac OS Extended (Journaled)
The TC can handle FAT32, but that is still to be avoided.. it cannot read or write files to NTFS.
So the other aspect of this might be remote access.
If you need access to the TC away from home this is possible via the Apple Back to My Mac and iCloud system.
Read up about that.
http://support.apple.com/kb/ht3486
And the whole icloud thing.
http://www.apple.com/au/icloud/
You must use AFP for remote access into the TC.. this is a bit confusing but SMB is not offered to WAN side. It is too risky for one thing. And most ISP block it anyway. AFP is a much more secure protocol.
That means you cannot access the TC from windows machine.. not that I know of at least remotely.
Now none of this is impossible without a standard NAS from QNAP or Synology. Just google for those brands.. they are the most popular brands for this task on the market. They both can do Time Machine and talk to Apple computers without trouble.. they also of course talk to PC and you can share files.
It is going to cost more than a TC.. but it has the following improvements.
TC is designed primarily as a back up target for Time Machine. It has no way to back itself up. If you store files on the TC it can be difficult to back them up. Especially from the Mac side because TM can NOT read network drives.. only write to them.
Every NAS made has some method of continually backing itself up as well as raid system to handle disk failure. TC has none.
NAS will not offer btmm and icloud but will offer FTP SFTP and HTTP and HTTPS access to the WEB for remote connection. None are offered by the TC.
So there is some rambling. In response to yours.
Main point.
In Mac + Win world.. formats of disks are a problem. Neither can speak natively the one the other uses.
But Networks are the answer. Anything you wish to move or copy or share between Mac and Win is easy over a network, because they are then forced to talk the same language.
