Hi Ross, personally I haven't been to HK b4, but I have compiled a list of camera shops in HK just in case i have a opportunity to go there one day. The list is courtesy of one of our fellow CSer, here it is:
-Kowloon Photo (in Yau Ma Tei)
-Wing-Shing (in Mong Kok)
66 Sai Yeung Choi ST., Mongkok, Kowloon
Tel: 2396 6881, 2369 6961
Business Time: 10am - 8pm
Take the MTR to Mong Kok Station and exit via EXIT D-3. From there it is easy to get to both MAN-SHING and WING SHING.
-Man Shing (in Mong Kok)
106, Tung Choi Street, Kowloon, Hong Kong Tel:
2396 2996, 2395 6684 Fax: (852) 2395 2127
1) Cheer Power Camera & Audio
Hung Kei Mansion, Queen Victoria Street, Central, Hong Kong
Tel: 2877 1511, 5369 8822
Business time : 10am - 7pm
2) Kwong Tai Photo Supplies Co. Ltd.
30A Stanley St., Central, Hong Kong; tel: 2522 8648
Business time : 10am - 7pm (close on Sunday)
3) Photo Scientific Appliances Ltd
6 Stanley Street, Central, Hong Kong; tel: 2522 9979
Business Time: 0900-1900 (Closed on Sunday)
4) Stanley Photo Supplies
Stanley Street, Central, Hong Kong; tel: 2525 2290
5) Mirama Camera & Hi Fi Co. Ltd
25 Stanley Street, Central, Hong Kong
tel: 2525 0501
Business time : 10am - 7pm
6) Salon Camera & Radio Co.
Groundfloor, 3 Lchang Street, Tsim Sha Tsuim Kowloon
Tel: 2376 0906
Business time : 10am - 8pm (Closed on Sunday)
7) All Best Camera & Watch Co.
Ground floor, Shop 4 Champangne Court, 16 Kimberley Road, Kowloon; tel: 2739 1826
8) For used equipment, go to Tin Cheung Camera Co. in the shopping arcade of Tung Yin Building, 100 Granville Road, Tsim Sha Tsui, Kowloon; tel: 2368 7518 (Tung Yin Building is adjacent to Champagne Court) .
Good service, need to bargain price. The most well stocked shop for new/used Leica. Well-stock in 135, 120, 4x5 cameras and lenses. They also carry brands like Gitzo , Manfrotto, Domke, Tenba, Lowepro. This shop offers very good customer service.
9) Kowloon Photo Service
Groundfloor, 5, Woosung Street, Yaumati, Kowloon, Hong Kong. Tel: 2384 9302
Good selection of Photo gear. Prices are at least 5-10% less than the best prices of the shops in Central. Personnel are typically polite. Carry Lowe Pro Bags, Darkroom stuff as well as Nikon scanners. Take the MTR to JORDAN station exit from Jordan Station and walk up NATHAN ROAD ( away from Victoria Harbour). Kowloon Photo is off Nathan Road to the left near the Jade Market.
Business time : 11am - 9pm
10) Foto Photo Supplies Co.
G20 Hung Hom Sq., 37-39 Ma Tau Wei Rd., Hung Hom Kowloon
Tel : 2363 0179
Business time : 11.30am - 8pm
http://www.glink.net.hk/~npc/foto/index.html
11) Matsuya Camera & Video Centre
Shop 15, Tsim ShaTsui Mansion, 83-97 Nathan Rd, Tsim Sha Tsui, Kowloon
Tel : 2724 0893
Business time : 10am - 8pm (Close on Sundays)
http://www.matsuyacamera.com.hk/
12) Zhao Xiang Guan
Shop G36, Tung Ying Building, 100 Nathan Rd., Tsim Sha Tsui, Kowloon
Tel : 2722 0068, 2722 0161
Business time : 11am - 8.30pm (Close on Sundays)
Some of those shops above sell 2nd hand items also, hope it helps. Enjoy your trip