Group-photo-sharing app Cluster is a worthwhile app, even if you don't envision yourself sharing photos with a group. That's because in addition to letting you easily create group photo albums to which all members can contribute, the app also does an admirable job of organizing the mess that is your iPhone's Camera Roll.
After installing Cluster, you'll need to sign up for an account via Facebook or e-mail. Once you have signed up, you can then create a group album -- a cluster, if you will -- organized by event or topic. Choose event and you'll browse the photos on your iPhone by date, with a handy link to select all photos from a certain date to add to a cluster. If you create a topic-based cluster, you simply get the default view of your Camera Roll (or album on your iPhone) -- a grid of thumbnails as far as the eye can see.
There are four steps required to create a cluster:
1. Pick the photos.
2. Give the cluster a name and choose whether it should be private or public. Anyone can view a public album, but only those invited can add photos to it.
3. Add time and location parameters to the album. These two fields are filled out for you, but you can edit them.
4. Send out invites for others to join. You can have the app send invites or give you an access code that you can disseminate yourself.
For those without the app, you'll get a link that will let you view the photos in Safari with a button to take you to Cluster's page in the App Store. If you share a cluster with someone who already has the app, the cluster will simply appear in his or her feed.
Five navigation buttons run along the top of Cluster. The settings button on the left lets you edit your profile and tweak how and when the app will send notifications. The "+" button on the right lets you create a new cluster. The three buttons in the middle show you the three views. The home button displays your feed of clusters -- shared albums you created or were invited to share. The people button displays a feed of public albums you or your friends created. You'll see a button to join a public album to which you have yet to be invited. The phone button shows you a feed of all of the photos on your phone, neatly organized by date and location. These automatically created groups of photos of your Camera Roll can quickly be turned into a cluster to share amongst friends.
When viewing a cluster, you can tap the upload button in the upper-right corner to add photos to it. Tap the speech-bubble button or just pull down on the cover photo to view the cluster's activity -- who created the cluster, who has joined and added photos, and so on. Double tapping on the cover photo lets you view the details of an album and, if you are the creator of said album, you can edit the details (basically, the title and privacy setting).
Open a cluster and you'll see a grid of thumbnails. Tap the Sort button in the lower-left corner to sort by upload time, time taken, photographer, or favorites, which moves all favorited photos to the top. Tap on a thumbnail to expand the photo. From here, you'll find buttons to comment on the photo or mark it as a favorite. There is also a button to remote the photo from the cluster, save it (download as either a low- or high-resolution shot), set it as the cluster's cover photo, and share it (e-mail, text, Facebook, or Twitter).