Programming really isn't my field - you'd better ask Phil. 编程真的不是我的专长,你最好问问菲尔。
Botany isn't really his field, but he likes to be able to identify plants when we go hiking.
Engineering isn't really my field - I was always more on the logistics side of things.
She's a confident singer, but surprisingly diffident when it comes to anything outside her field.
Byzantine history is totally outside my field.
See also: field noun (AREA OF INTEREST)