Dating old photos

Dating old photos can be a daunting task.  If the photo is labeled with your ancestors name the dating becomes much easier.  However, if the photograph is unlabeled with no photographers mark you have a real dilemma as to when and where the photo was taken.  While doing research for Jewel’s Heirlooms I found this site: Cycleback.  Their information on dating early mounted photographs is the best resource I have found on the web.  I could try to distill all the information on the site here but their information is so well done I thought a link to their site would be more useful.