Electronic products of big brands purchased in Hong Kong are generally guaranteed in the Mainland. You need to have formal purchase vouchers and warranty vouchers, and the store will stamp you with the warranty stamp. In the past, Nikon had to send the warranty vouchers to the Hong Kong headquarters for registration. I wonder if there is such a regulation now. You can ask specifically when you buy them. Canon is similar. So when you buy, you must choose a bigger and reputable store. In addition, if you have time, you can visit more different places. For example, the prices and stocking of the same shops in Mong Kok and Yuen Long are different. If it is too troublesome, just ask a few more shops where the shops in Sai Yeung Choi South Street in Mong Kok are concentrated. Yuen Long is far away.

Because there are so many mainland tourists who buy cameras and Apple products in Hong Kong, the answers to such questions there are very mature. If you buy it, it's actually Okanagan Valley, Broadway, Wancheng, Yong Cheng, Suning, etc. You can use a mainland credit card or exchange it for cash payment in Hong Kong dollars, which requires you to actually calculate which one is cost-effective. It seems that some stores will get further discounts on cash payment.

it depends on luck when you pass the customs. Generally, it's not a big problem to buy it yourself, unpack it and take it separately. It's okay to bring it in a handbag or plastic bag, but at most it's just a tax payment.