Hello, 

I am trying to identify this sans serif that was used on Saul Leiter's letterhead in the 60s in New York.

It's a scan from an original document, that's why it looks so distressed.

I have found a few close matches, but not a 100% one (Century Gothic, Wes FY Reg being the closest). Any other suggestion?

 

Hard to be sure with so few letters in the sample, but Vogue seems a likely candidate.

 

Here is some history of the face. Intervogue Light would be a good modern interpretation.