[dcfandy]

CHING 我想知支鏡影花,是否對焦時大多數時候會有迷焦,要手動對焦?
另外Kenko extension tube set 影花有時候都會有迷焦要手動對焦.
2者影花都一樣嗎?

[Hgdgdgg]

No such problem on my 100mm. May be yr focus point settings with error

[JSmith]

係咪 set咗 full range auto focus呀？
或者太近主體？

[dcfandy]

或者太近主體! THX

[klchan23]

I have 2 100mm Macro at my home. One is from my friend. Both of them is working very well. I think it is just another depth of field problem.
When shooting at 100mm F/2.8 focus point at 0.3m. The DOF is actually very very close to 0. Which means if you move your camera back or frowards by 0.1cm, you will miss the focus point.

Use a tripod should solve this problem.
Try this DOF calculator. You should understand the DOF of every len at any range.
http://www.dofmaster.com/dofjs.html