Making his debut as a cinematographer in 1994, Pun is known for his collaborations with director Benny Chan, and he won Best Cinematography in the 42nd Golden Horse Awards for their action film Divergence (2005).

[15] Jay Weissberg of Variety praised Pun's "masterful ease with complicated spatial constructions", noting that he was "clearly enjoying the expansive possibilities of scope".

[26] The same year, Pun returned to shoot the sequel Overheard 2, for which Hugo Ozman of Screen Anarchy praised him for the film's high production value and called the action scenes "wonderful".

[30] Pun collaborated with Chan again on the 2013 crime thriller The White Storm, followed by Mak and Chong's Overheard 3 in 2014,[31][32] earning him nominations in the 33rd and 34th Hong Kong Film Awards.

[38] Clarence Tsui of The Hollywood Reporter praised his camerawork for "getting the best out of [the child actors'] raw performances",[39] while Maggie Lee of Variety noted that Pun effectively captured "the drab New Territories and crumbling school with the plainest of shots".

[44] Clarence Tsui of The Hollywood Reporter lauded Pun for bringing "immaculate special effects" and "impressive production design" vividly to the forefront.

[54] That same year, he also served as cinematographer for Jack Ng's A Guilty Conscience,[56] which currently holds the title of the highest-grossing domestic film in Hong Kong.

[59] Keith Ho, writing for HK01, praised the film's cinematography as "brilliant", crediting Pun for bringing back "the dazzling era of Hong Kong to the big screen".

[61] James Marsh of Deadline Hollywood noted that Pun's dual role ensured "that the unfolding mayhem retains a visual coherence", acknowledging his ability to strike a balance between disastrous scenes and images that resonate with the preceding pandemic and protests, serving as a political satire packaged with "boisterous, breathless" vibes;[7] while Edmund Lee of South China Morning Post also commended Pun for effectively blending "firefighting action, government workplace bureaucracy, nefarious business practices and epic effects sequences", which "vividly picture the city in ruins".