[千紅]

想問以上2個 是不是都支援全時手動?

[h0001244]

So far I know, YES

[wesleyyau]

http://en.wikipedia.org/wiki/Canon_EF_lens_mount

There are two types of USMs, the ring-type USM and the micromotor USM. Ring-type USM allows for full-time manual focus (FT-M) operations without switching out of AF mode. Micromotor USM is used to bring down the cost of the lens. It is possible to implement FT-M even with micromotor USM; however, it requires additional mechanical components, and the vast majority of micro-USM lenses do not offer FT-M.

有兩種USM ring-type 同 micromotor, ring-type USM 有FT-M, micro USM 冇FT-M.