Date your old photograph
Below is a list of links to photographic processes, links to sites which, I’ve used over the years to help date my own personal photographs. These maybe helpful to you if you are tracing your family tree, and have old photos of family members you are not sure of.
PHOTOGRAPHIC PROCESSES

Photo Credit –https://commons.wikimedia.org/wiki/File:Harvard_Daguerreotypes_-_sAg_168.70.1.jpg
http://www.phototree.com/id_dag.htm
https://blog.scienceandmediamuseum.org.uk/find-out-when-a-photo-was-taken-identify-daguerreotype-photography/
http://www.graphicsatlas.org/identification/?process_id=366

Photo Credit – https://commons.wikimedia.org/wiki/File:William_Henry_Fox_Talbot,_View_of_the_Boulevards_of_Paris,_1843.jpg
https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/atlas_saltprint.pdf
http://www.graphicsatlas.org/identification/?process_id=269

Photo Credit – https://commons.wikimedia.org/wiki/File:Ambrotype_of_a_baby_with_cuttings_of_hair_under_the_glass_(3588772191).jpg
http://www.phototree.com/id_amb.htm
https://blog.scienceandmediamuseum.org.uk/find-out-when-a-photo-was-taken-identify-collodion-positive-ambrotype/
http://www.graphicsatlas.org/identification/?process_id=283

Photo Credit – https://commons.wikimedia.org/wiki/File:Group_portrait,_family_of_five,_Cased_tintype,_half_plate.jpg
http://www.phototree.com/id_tin.htm
https://blog.scienceandmediamuseum.org.uk/find-out-when-a-photo-was-taken-identify-ferrotype-tintype/
http://www.graphicsatlas.org/identification/?process_id=280

Photo Credit – https://commons.wikimedia.org/wiki/File:Queen_Victoria.jpg
http://www.phototree.com/id_cdv.htm
https://blog.scienceandmediamuseum.org.uk/find-out-when-a-photo-was-taken-identify-a-carte-de-visite/

Photo Credit – https://commons.wikimedia.org/wiki/File:%C3%89tienne_Carjat,_Portrait_of_Charles_Baudelaire,_circa_1862.jpg
http://www.graphicsatlas.org/identification/?process_id=38
https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/atlas_woodburytype.pdf

Photo Credit – https://www.goodfreephotos.com/spain/other-spain/the-library-and-the-chapter-at-the-cathedral-collotype-1889-in-santiago-de-compostela-spain.jpg.php
http://www.graphicsatlas.org/identification/?process_id=26
https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/atlas_collotype.pdf

Photo Credit – https://commons.wikimedia.org/wiki/File:Werner_Haberkorn_-_Via_Anchieta._S._Paulo_a_Santos._panorama_Fotolabor_-_53.jpg
http://www.graphicsatlas.org/identification/?process_id=303

Photo Credit – http://www.graphicsatlas.org/identification/?process_id=104
http://www.graphicsatlas.org/identification/?process_id=104

Photo Credit – https://commons.wikimedia.org/wiki/File:Aubrey_Beardsley_LCCN95500934.jpg
http://www.graphicsatlas.org/identification/?process_id=125

Photo Credit – https://commons.wikimedia.org/wiki/File:Hb_3343412.jpg
http://www.graphicsatlas.org/identification/?process_id=343

Photo Credit – https://commons.wikimedia.org/wiki/File:Andrew_Jackson-Related_Collodion_Print_Photographs,_1897_(4359293217).jpg
http://www.graphicsatlas.org/identification/?process_id=296

Photo Credit – https://commons.wikimedia.org/wiki/File:Emma_Barton_-_The_Awakening.jpg
http://www.graphicsatlas.org/identification/?process_id=306

Photo Credit – https://commons.wikimedia.org/wiki/File:Postcard._Greetings_from_the_dear_Homeland._Wildt_and_Kray,_London,_N.W._Series_no_1819._Printed_in_England._(1910)._(21643308556).jpg
https://blog.scienceandmediamuseum.org.uk/find-out-when-a-photo-was-taken-identify-a-postcard/

Photo Credit – http://loc.gov/pictures/resource/ggbain.03485/
http://www.graphicsatlas.org/identification/?process_id=364

Photo Credit – https://commons.wikimedia.org/wiki/File:Accession_Number-_1982-2070-0002_(2678237668).jpg
http://www.graphicsatlas.org/identification/?process_id=301

Photo Credit – http://www.graphicsatlas.org/identification/?process_id=326
http://www.graphicsatlas.org/identification/?process_id=326
CLUES IN PHOTOGRAPHS
https://blog.findmypast.co.uk/family-photos-what-are-they-wearing-1406240689.html
https://www.worthpoint.com/articles/blog-entry/dating-vintage-photographs-1840-2
https://vintagefashionguild.org
http://www.internet-genealogy.com/Dating%20Old%20Photos.pdf
http://thephotoorganizers.com/dating-identifying-old-family-photographs/
http://www.cartes.freeuk.com/time/time.htm