From Longman Dictionary of Contemporary Englishphoto finishˌphoto ˈfinish noun [countable] DSthe end of a race in which the leading runners finish so close together that a photograph of it has to be examined to decide which is the winner
Examples from the Corpus
photo finish• Latest polls suggest Sunday's election will be a photo finish.• Here the officials checked your number and gave you your side number, for the photo finish. 