Many know the late Chinese artist Wu Guanzhong for his renowned ink and oil paintings. But few have had the chance to glimpse the man behind the canvas.

Now, they can do that at an Arts House exhibition that showcases more than 50 photos. These photos were taken by acclaimed Singaporean photographer and gallerist Chua Soo Bin of Wu, his friend, often in rare, unguarded moments.

The exhibition Light Within Ink, which opened last Saturday and will run till Sept 19, is the first solo show in Singapore in more than 11 years for Chua, who received the Cultural Medallion for photography in 1988.

"I don't consider these works to be of great artistic quality," says the 85-year-old in Mandarin. He took the photos of Wu over about 20 years. "Rather, it is a precious record of our friendship."

Wu, who was born in Jiangsu, China, and is considered to be one of the greatest contemporary Chinese painters, died in 2010 at age 90.

Chua, the founder of gallery Soobin Art Int'l, befriended Wu in the 1980s and has sold more than 100 of his works.

Unlike the careful deliberation of the 1988 Legends series, for which Chua photographed 14 Chinese ink master painters, the photos of Wu are more informal and spontaneous.

In a triptych of shots taken in Wu's studio, the painter rips up works that he is dissatisfied with in a flurry of displeasure.

In another at Jurong Bird Park, Wu sits bedecked with parrots, which he was painting for his 1998 work Parrot Haven. "This one is very cute," says Chua. "He was so amused at how they could talk back to him like humans."

Chua captures Wu in a variety of locales, from The British Museum in 1992, when Wu became the first living Chinese artist to have a solo show there, to the floating markets of Thailand, which Wu was drawn to because he came from a water town.

The photos are in black and white with one exception: a portrait taken in Chua's Oxley Road studio, where he had Wu paint in the air with torch lights in different colours and photographed him using a long exposure. The whole process took two hours and the final product has the effect of Wu standing in the dark, conducting many-hued swirls of light.

"To truly understand a person in your photography takes time," says Chua, who is married with three sons. "It is like shooting scenery - you wait for dawn, you wait for the sun to come up, you wait for the perfect moment. People are like that too."

Chua shot his final portrait of Wu in 2008 during a visit to Wu's home in Beijing as part of a Singapore delegation conferring the Distinguished Patron of Heritage Award on him for his generous donation of paintings to Singapore museums.

That year, Wu donated his largest collection of 113 ink and oil paintings, valued at $73.7 million, to the Singapore Art Museum.

The room was packed with dignitaries, so Chua crawled under a table and, from that angle, captured his friend's face for what would turn out to be the last time.

He describes Wu as "not at all proud, a person who would always speak his mind".

"When he died, I was sad. He was a truly good friend."

He is in talks to take the exhibition on tour; two locations - Zhejiang Art Museum and China Art Museum - are already confirmed.

"I would like artists especially to come see this exhibition," says Chua. "It will help them understand the other side of a great artist."