Authentic vintage posters can be difficult to find - just as authentic art is much more difficult to find than recreated prints. Fortunately, where authentic art will only have 1 original copy, authentic vintage posters are likely to have multiple prints in circulation. When you refer to authentic vintage posters, you refer to the original poster passed out by the manufacturer of the poster. While it is easier to get your hands on one of these than an original piece of art, there are other problems that can crop up with posters.
First is the quality of the print. People tend to tag posters to their walls, or even tape them - inevitably when they are taken down, at worst the tape will be torn off, sometimes tearing the poster itself. You also face the issue of wear and tear - posters are printed on paper, which doesn't necassarily stand up to the test of time as well as a canvas would. You might get lucky and find a poster that's been handled with care, possibly framed, but you could just was well find one thats been rolled up or folded for years, causing damage that cannot be repaired.
