The high-res camera on the iPhone 4S is a blessing and a curse. Its high-resolution sensor lets you capture crisp, clear images, which then motivates you to snap more photos. The downside is this collection of high-res photos begins to eat at your iPhone's available storage. Enter Cloud Photos (99 cents), a camera app that saves photos to your Dropbox account, freeing up space on your iPhone for apps, music, and other content.
After you launch the app, you'll be greeted with two buttons: one allows the app access to your Camera Roll and the other connects you to your Dropbox account. After you have made the requisite connections, you'll be asked whether you'd like to copy all of your Camera Roll pictures to Dropbox. It's a convenient way to back up your library or step 1 in the process of culling an overgrown collection of photos. If you don't take this step now, you can always copy the entirety of your Camera Roll to Dropbox later.
The home screen of the Cloud Photos app shows your Dropbox folders and local folders (Camera Roll, Photo Stream, and any local albums you have created). Cloud Photos creates a Photos folder in Dropbox, and you can create new Dropbox folders by tapping the button in the lower-left corner.
To snap a picture, tap the camera-icon button at the bottom of the app. In the top left-corner, you get controls to switch between the front- and rear-facing cameras and control the flash, plus advanced controls for white balance, focus, exposure, and showing grid lines. The folder where the photo will be saved is listed in the lower-left corner; tap on this button to change folders.
If you have a Dropbox folder selected, a photo will be uploaded to Dropbox and will not show up in your Camera Roll. You can use the app, however, to browse the photos stored in Dropbox folders; the app saves a large thumbnail that looks indistinguishable from locally saved photos when viewed at full screen. Syrp, the developer of Cloud Photos, claims these thumbnails take up 1/40th the space as an original photo.
You can easily move and copy photos and entire folders, making it easy to transfer photos from Dropbox to your iPhone and vice versa. Tap the share button in the top-right corner and move, copy, share, and delete buttons appear along the bottom of the app. You can also swipe on an album on the list to reveal the move, copy, share, and delete buttons.
The app also features a Private Share function, but you'll need to access Dropbox via the Web to set up a shared folder and send invites to friends. You can't set up the Photos folder as a shared folder, but you can share any subfolder in the Photos folder. Then when you snap photos with Cloud Photos to that folder, the friends you invited to share that folder will be able to see them. And any photos they add to the folder, you'll be able to see using the app.
Lastly, in settings, you can set the app to upload via 3G or only Wi-Fi. You can also set it to open to the camera view instead of the folders view, decreasing the odds of missing your next photo opp.
For other photo-transferring apps, I kindly direct you to my previous coverage ofand .