The new location was down a lane in a residential community on Julu Road. Old residents basked under sunshine, with colorful laundry drying overhead on bamboo poles. There were no more big posters or shop windows, only a small signboard hung at the entrance of the alley.

"Many of our old customers did not know the studio moved and thought it shut down for good," Zhang says.

He reveals that the idea to provide free shoots for its old customers was inspired by a call last year.

"An old woman speaking in Shanghai dialect called and asked whether it was the People's Photo Studio. She asked every detail including the former name and address of the studio and finally believed it was the same one she took photos in decades ago," he recalls.

The woman was a 90-year-old Shanghai native who now lives in the United States, Zhang says. Her family photo, silver and golden wedding anniversary photos were all taken at the People's Photo Studio. In 2012, she returned to Shanghai and wished to take a family photo again at the studio, only to find it was no longer on Huaihai Road.

More than 1,000 old couples have registered for the free-shoot since the promotion was made public.

Among the couples was a pair wanting to mark their golden wedding anniversary.

"They wore Western suits and wedding gowns when they took the photos 50 years ago. But during the 'cultural revolution' (1966-76), the dress was seen as a taboo representing bourgeois lifestyle. They had to destroy the photos. Now they want to regain what they have lost," he says.

For Gong Lianhong and his wife, the opportunity to retake their wedding photos was a surreal family experience. Their 28-year-old son was part of the photo shoot.

"We had planned to take photos here again as this year is our 30th wedding anniversary," he says.

"We took our wedding photo in 1983. I remember there was a barber shop next to the photo studio. My wife permed her hair before we walked into the studio. I was so happy that day, I had a very big smile while taking the photos, which made my eyes look small on the photo. So we came here again for a second shoot," he recalls.

His son is now planning his wedding. Gong hopes his son will also take his wedding photos at the studio.

Zhang the vice-general manager hopes the promotion will trigger more people to think about the meaning of marriage.

"China has seen turbulent days over the past decades. Most old couples experienced hard lives but they overcame difficulties together. That's why they treasure their marriage and have the chance to come back for the photo shoot."