Guys, paiseh for late reply.....got back home late from work today.
Quite frankly, I seldom shoot macro w/o Close up lens, but I think lifeworld is right, and base on what I played with earlier, I don't think Macro mode has any difference in the ability to focus, and I have mostly used M mode or A mode and it focus just fine. Perhaps some others may have found it differently?
5 cm is a general guide, and its distance from lens to subject. When subject is out of focus, it can be afew reasons:
1) distance is too near, (as sunkist mentioned) and camera cannot focus. So use MF, and move the camera and see agar agar at what position the image is sharp. Can leave it at MF or switch to AF to focus. (this applies also to Close up lens attachment)
2) whats the shutter speed? Using tripod? If image is in focus, but shutter speed very slow, and handheld, than camera shake may just make the imge soft.
3) As Hong Jia mentioned, Spot mode would help. I am using the FZ10 and it only uses the center to focus. I understand that the FZ20 has some multiple focus pt? or something like that? Anyway, even if I have that function, I would select the single focus point, cos I want to DECIDE which part to be in focus. Spot mode would shrink down that area to specifically which part you want to be in focus. In normal mode, the image may be focused, but at the wrong part, and image may appear out of focus. This especially so if using CU filters, as the DOF is very sensitive....you know the [ ] box may just cover the whole insect when you wnat the eyes to be in focused.
BTW, with CU filter, you can use AF mode, and I understand the difficulty, thats why I use pt 1 above to get in focus. For e.g. the recent Sungei Buloh DF shots were taken with Nikon 6T in AF mode (if I remember correctly)
Perhaps this 3 pts may be a possible cause, well from my experience anyway. There may be more reasons, where others may be able to help fill in.
To me, for macro, ext flash is quite essential, as it allows you to take the pic with a small apteure (F8) and faster shutter speed. I would say 98% of my shots are with ext bounce flash.
hope my 2c helps :dunno: