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

Photo Credit –https://commons.wikimedia.org/wiki/File:Harvard_Daguerreotypes_-_sAg_168.70.1.jpg
More info can be found below.
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
More info can be found below.
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:-Collection_of_British_Calotypes_and_Wood-engravings-_MET_DP70833.jpg
More info can be found below.
https://www.loc.gov/rr/print/coll/589_calotype.html
https://www.gla.ac.uk/myglasgow/specialcollections/collectionsa-z/hilladamson/calotypeprocess/

Photo Credit – https://commons.wikimedia.org/wiki/File:Anna_Atkins_Cystoseira_granulata.jpg
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=319
https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/atlas_cyanotype.pdf

Photo Credit – https://commons.wikimedia.org/wiki/File:Ambrotype_of_a_baby_with_cuttings_of_hair_under_the_glass_(3588772191).jpg
More info can be found below.
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:Early_portrait_of_a_rather_plump_Victorian_gentleman_-_glass_wet_plate_collodion_negative_(5061962270).jpg
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=352

Photo Credit – https://commons.wikimedia.org/wiki/File:Group_portrait,_family_of_five,_Cased_tintype,_half_plate.jpg
More info can be found below.
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
More info can be found below.
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:Arch_of_Titus_by_Romualdo_Moscioni._Albumen_Print.jpg
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=143
https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/atlas_albumen.pdf

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

Photo Credit – https://commons.wikimedia.org/wiki/File:Chester_A_Arthur_Cabinet_Card_by_CM_Bell,_1882.jpg
More info can be found below.
http://www.phototree.com/id_cab.htm
https://blog.scienceandmediamuseum.org.uk/find-out-when-a-photo-was-taken-identify-a-cabinet-card/

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
More info can be found below.
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:Alfred_Stieglitz_-_The_Last_Joke_Bellagio,_1887.jpg
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=271

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

Photo Credit – https://commons.wikimedia.org/wiki/File:Frederick_Douglass_LOC_collodion_c1865-80.jpg
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=222
https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/atlas_collodion.pdf

Photo Credit – http://www.graphicsatlas.org/identification/?process_id=104
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=104

Photo Credit – https://commons.wikimedia.org/wiki/File:Model_in_New_Look_fashion_on_steps_of_the_Public_Library_of_New_South_Wales,_1950__silver_gelatin_photoprint_by_Rob_Hillier_(7785514320).jpg
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=266

Photo Credit – https://commons.wikimedia.org/wiki/File:Aubrey_Beardsley_LCCN95500934.jpg
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=125

Photo Credit – https://commons.wikimedia.org/wiki/File:Hb_3343412.jpg
More info can be found below.
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
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=296

Photo Credit – https://commons.wikimedia.org/wiki/File:Emma_Barton_-_The_Awakening.jpg
More info can be found below.
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
More info can be found below.
https://blog.scienceandmediamuseum.org.uk/find-out-when-a-photo-was-taken-identify-a-postcard/

Photo Credit – http://loc.gov/pictures/resource/ggbain.03485/
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=364

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

Photo Credit –
Alfred Roller (1864–1935) 1909 © Madame d’Ora (1881–1963) Arthur Benda (1885–1969)
More info can be found below.
http://www.graphicsatlas.org/identification/?process_id=347

Photo Credit – More can be found
http://www.graphicsatlas.org/identification/?process_id=326
CLUES IN OLD PHOTOGRAPHS
What Are They Wearing.
https://blog.findmypast.co.uk/family-photos-what-are-they-wearing-1406240689.html
Dating Vintage Photos.
https://www.worthpoint.com/articles/blog-entry/dating-vintage-photographs-1840-2
Vintage Fashion.
https://vintagefashionguild.org
Fashion Expert.
Genealogy.
http://www.internet-genealogy.com/Dating%20Old%20Photos.pdf
Identify Old Family Photos.
http://thephotoorganizers.com/dating-identifying-old-family-photographs/
Old UK Photo.
http://www.cartes.freeuk.com/time/time.htm