>>Change to A/S/P mode and switch the multi-point to single point with continuous or single point focus.<<
For the early tests I was on manual mode. For the shoot itself I was on shutter priority to maintain sync with a radio-triggered flash. Focus mode was always AF-S to lock exposure so I could re-compose the shot. I find the AF-L/AE-L button much too clumsy to use.
Single-point failed almost every time. I used multi-point most of the time in the actual shoot. Here are some sample overviews of tests the day before and of the shoot day showing focus point: http://tinyurl.com/3gpsup2
On 0877 I focused on the near eye with the single point and recomposed the shot. Here is a 100% crop of the eyes as the D5100 chose to see it: http://tinyurl.com/3rn4ydq
That's the 18-55mm, 55mm @ f5.6.
Shot 0882 is another 18-55mm, 36mm @ f5, focused on the left eye and recomposed. Here is a 100% crop: http://tinyurl.com/4ytu4tx
The same situation with the 55-200mm, 75mm @ f4.2: http://tinyurl.com/3lugdzs
Click on the image to view at 100%.
>>"If you fight technology, you will always loose."<<
I couldn't agree more, however I'm not the one picking the fight. Images 0946, 0951, and 0963 are all examples of the throw of the dice that is the D5100 AF system. In these examples the dice fell in a bad place. Needless to say, these were all focused on the wrong place. I do not chose what the suckers decide to pick, the camera does. I had to constantly knock the lens out of focus and refocus and hope it picked the correct spot, as it did in example 0979.
>>The manual or a book on the camera maybe your next stop.<<
>>You really need to read the user manual and learn how your camera works. <<
Contrary to popular belief, I did RTFM. I saw no revelatory information in there that would point out how I make the camera focus where *I* want it to focus. It decides every time. No match for the D5100's IQ, but here's the Fuji S9000 on the first shot: http://tinyurl.com/3nf8a42
Click on the image to see at 100%
>>you are using 18-55 & 55-200. these are 3.5-5.6 and 4-5.6 and as such do not have shallow DOF<<
They certainly can, perhaps not what you get from a larger aperture optic, but if you look any of the examples I've posted here you can clearly see the need for critical focus, where YOU want it. That's the point I'm trying to make here. Here's another (downsampled) example of a shot that fortunately went well: http://tinyurl.com/3wzf6sr
Click on the image to see full res. That's the 55-200mm, 175mm @ f5.3. So yes, you can can fairly shallow DOF with these optics.
I think that generally speaking you'll get "good enough" focus from this system. After all, most people wouldn't care if the left eye or right was in focus. If you print out any of the images I pointed out above there were focused in the "wrong" place, they wouldn't appear out of focus, but it's not focused where *I* want it, in these examples it is the eyes, or a specific eye.
I still think a central cluster of focus points would make for better focusing then this splattered grid. Time and again it decides to pick someplace other than where I want it, other times it hits dead on. It's been a complete throw of the dice for me.