Ohara is most noted for his series of photographs titled ONE, in which he presents anonymous faces with standard size and tone.
In 1970 while working as an assistant to HIRO and Richard Avedon, he published ONE, which contained more than 500 tight close-ups of anonymous people's faces he shot on the New York streets.
In the last 50 years since then, Ohara has achieved a series of experimental portrait projects in varied formats.
They include self-portraits shot every minute for 24 hours (24 Hours), daily photo journals for the duration of one year (Self-Portrait 365 series), and the portraits of 123 local residents near his studio with whom he shots while opening a camera shutter for exactly 60 minutes (with series).
Ohara's work offers an intense examination of space and time in portraiture and provokes a rethinking of the limits of photographic depiction.