Photo steam is not on your device, it is synced via iCloud. Sounds like the iPhone hard drive is full, and you would need to delete some of the data you have off of it.
The following items do not count against your iCloud storage space:
- Photo Stream
Photo steam is part of iCloud. For info on what iCloud stores, see this article - http://support.apple.com/kb/HT4847.
Thanks for your response. When I sync photos, I have unchecked "sync photos" but the storage bar still shows 90% of the phone's harddrive is photos. If it's not from photostream or my computer, I suspect the camera roll is responsible - but how do I delete, say, the oldest 500 photos? And will they still be accessible via photostream?
No. If you delete them from the camera roll, they delete from Photo Stream. You need to go to your computer, and save your images from photo stream to your computer.
What type of computer do you have? A mac? or a Windows computer?
On a mac By default, photos from Photo Stream automatically save to the iPhoto or Aperture library. On your PC all of your photos will be imported into C:\Users\<user name>\Pictures\Photo Stream\My Photo Stream.
If you delete them from the camera roll, they delete from Photo Stream.
That is not correct, you can remove photos from Camera Roll with no effect on Photo Stream. Photo Stream holds up to 1000 photos, and only for a period of time (I think 60 days). Also, if you view Photo Stream on your device, the pictures are stored locally so these do count against your device storage.
You need to go to your computer, and save your images from photo stream to your computer.
If the photos are in Camera Roll, that's where they need to be saved to the computer from, not Photo Stream.
The process for the OP would be:
1- Make sure important photos in Camera Roll are transferred to the computer.
2- Delete some (or all) photos in Camera Roll.
3- Optional -- create photo album(s) on the computer of photos to sync back to the iPhone through iTunes.
4- Optional -- delete unwanted photos from Photo Stream to reduce storage on your device.