Syncing iPhone 4S music only
From Apple's Web site:

To delete synced photos and videos
In iTunes, select the device icon in the Devices list on the left. Click the Photos tab in the resulting window.
Choose &quot;Sync photos from.&quot;
On a Mac, choose iPhoto or Aperture from the pop-up menu.
On a Windows PC, choose Photoshop Album or Photoshop Elements from the pop-up menu.
Choose &quot;Selected albums&quot; and deselect the albums or collections you want to delete.
Click Apply.

So, the albums you want to KEEP should be selected. They will sync with your iTunes account.
However, I prefer to store my photos directly to Dropbox. Dropbox can be set up to automatically sync photos to it using their Camera Upload feature.
Additionally, if you like the file system method, you can use an app like Phoneview to move photos manually into a directory of your choice.