I've been asked this question many times. So in an attempt to be helpful (which is not in my DNA, but I'm in a good mood today), here's the list I use to determine a poster's release date.
A lot of French posters have been reissued over the years. The only way to know if you have an original or a re-release is to look at the printer's name at the bottom of the poster. For instance, "For a Few Dollars More" was originally printed by St. Martin, Paris. However, there is an identical print that states St. Martin, Asnieres. It is because the printer moved from Paris to Asnieres (in the suburbs of Paris) and the movie was re-released in the late 70s. "The Deer Hunter" was originally printed by SE Lalande. Then the movie was re-released in the mid 80s and the printer reads SA Lalande. Again, same poster, one is original, the other is a re-release.
Here's the list:
CINEMATOGRAPHIE FRANCAISE
1925-1950
CINEMATO
1950-1964
Note: Both companies seem to overlap between 1947 and 1955. The oldest Cinemato I have seen is from 1947, the last Cinematographie is 1955.
ICP
Ends in 1960
RICHIER-LAUGIER
1927-1978 (much less after 1962)
BEDOS
Ends in 1962
HENON
Ends in 1964
LA LITHOTYP
Ends in 1965
AFFICHES ET PUBLICITE
Ends in 1969
GAILLARD
Ends in 1969
LALANDE
1956-1969 = Ateliers Lalande
1969-1971 = Lalande-Courbet
1971-1976 = Ste Exp Ets Lalande Courbet
1977-1982 = S.E. Lalande Courbet
1983-1986 = S.A. Lalande Courbet
ST MARTIN
1955-1975 = Paris
1975-1977 = Asnieres
CINE POSTERS (REPRINTS)
Cine Poster = 1980s;
SONIS
Sonis is not a printer but a distributor of posters from the late 60s on, which means that you will find Sonis' name on a poster along with St. Martin or Lalande. It doesn't mean you have a reprint. What's most important is the printer's name. If it corresponds to the movie's year of release, you're in the clear. But if it's a 70s movie without the printer's name and only Sonis, you have a reprint. Sonis was legit until the end of the 80s, at which time they decided to make extra dough by reprinting posters, but without the original printer's name. They reproduced some of the most successful movies, along with Cine Posters. They also reproduced US OS close to their original size, along with Zig-Zag.
In the late 80s, Sonis replaced Lalande as the official printer/distributor of French posters.
Hopefully, this list will help some of you.
T