Bostock suffered a suspected heart attack outside Spotland Stadium just minutes after the end of last week's Rochdale and Bradford City match.
Colleagues paid tribute to Bostock, who was married with two children and four step-children.
Observer sports editor Richard Partington told his paper that Bostock's photography reflected his great enthusiasm for his work.
He said: "Working for the Observer on a freelance basis gave him an outlet for his passion for photography and the paper benefited greatly from that...
"So impressive was his work that my wife and I asked him to snap our wedding day three years ago, and he did so with his usual panache...
"In decades to come, when people pore over back copies of the Observer, they will see his work brightening the pages, the images he captured so succinctly providing a fitting tribute and a lasting legacy."
His funeral is due to take place at Rochdale crematorium on Wednesday.
Taken from Press Gazette: http://blogs.pressgazette.co.uk/wire/6211.