1. macro photography require a macro lens (not the macro function on your camera). they offer at least 1:1 object image ratio.

2. there is for sure no restriction of focal length. havent you heard of the Zuiko 35mm f2.0 macro and its 50mm f2 version?

3. 会前面是糊 is percisely because the aperture is big!! large aperture results shallow depth of field. so only a small range is in focus and the rest is blurred.

4. and who sets the rule "macro 最忌前后有糊"?? background blur is one of the most used technique in photography, macro or not macro.