"I got to know how temperature and air composition can result in different star colors, such as blue and yellow that are shown in the images," he says.
"It is also thrilling when you can see something (in photos) in the great distance like the Andromeda Galaxy."
Dong met with Wu and sought his advice to hone his skills. Dong learned how to take control of elements and color in an image.
"You need to know what you want to express and how to find your own angle," he adds.
For the purpose, a high-sensitivity camera that brings down noises is required, and photos of different exposure time are needed for overlay later, he says.
Beaten trail
He threw his hat in the ring of the 2019 Astronomy Photographer of the Year competition. "It was well-known to people in the circle, so I wanted to put my skills to test through it."
Dong's self-confidence got a shot in the arm after winning the best newcomer award with his work, Sky and Ground, Stars and Sand.
"It was unexpected and a big encouragement," he says.