Thanks to everyone who responded to my email for help. I used several of the websites and was able to gain some new information as to the dating of the photos. There is no information about working with tintypes so I assume the only option is a digitized image. I will not bother with getting that done as these are sadly 3 unidentified men. One I have a suspicion but will never know for certain. So there is no justification for the expense at this point in time. Thank you again to everyone for their suggestions of websites - what a wealth of information. Jo Hogle