It was normal for professional wedding photographers to finish taking their photographs after the start of the reception.
Then they rushed back to their studios to produce proofs of what they had taken, code them and mount them for display. The mounted proofs were then rushed back to the reception where they were displayed for everyone to look at and place their orders.
The extreme haste was quite a feat because the photographs were on film that had to be developed and printed in a dedicated darkroom. Digital cameras were of course decades away.
The display of the proofs at the reception meant that guests were more inclined to order copies in the euphoria of the moment than they might have been later, which of course made financial sense to the photographers. They then sent out the completed orders later by post.
The immediate family and the bride and groom generally bought albums from the photographers. These came in white leather or simulated leather covers, embossed in silver lettering with appropriate words, and containing the printed photographs of their choice. These photographs were always black and white. Bound with each photo was a protective page of tissue paper.
(I am writing this as it contrasts so much with what I understand to be common practice nowadays where photographers sell a CD of their photographs along with the copyright to reproduce them. Presumably this must make more financial sense in a digital age.)
Of course guests always took their own photographs on their own cameras.
At my wedding, some of the guests of my age had colour slides film in their cameras.